initial work to adhere spec in handling memory access faults

(also i wanted to test if my comming signing works)

Cargo.lock

@@ -13,6 +13,12 @@ dependencies = [
  "version_check",
 ]
 
+[[package]]
+name = "beef"
+version = "0.5.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "3a8241f3ebb85c056b509d4327ad0358fbbba6ffb340bf388f26350aeda225b1"
+
 [[package]]
 name = "cfg-if"
 version = "1.0.0"
@@ -20,8 +26,21 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "baf1de4339761588bc0619e3cbc0120ee582ebb74b53b4efbf79117bd2da40fd"
 
 [[package]]
-name = "compiler"
-version = "0.1.0"
+name = "delegate"
+version = "0.9.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d358e0ec5c59a5e1603b933def447096886121660fc680dc1e64a0753981fe3c"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "syn 1.0.109",
+]
+
+[[package]]
+name = "fnv"
+version = "1.0.7"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "3f9eec918d3f24069decb9af1554cad7c880e2da24a9afd88aca000531ab82c1"
 
 [[package]]
 name = "hashbrown"
@@ -32,12 +51,39 @@ dependencies = [
  "ahash",
 ]
 
+[[package]]
+name = "hbasm"
+version = "0.1.0"
+dependencies = [
+ "hbbytecode",
+ "lasso",
+ "logos",
+ "paste",
+]
+
+[[package]]
+name = "hbbytecode"
+version = "0.1.0"
+
 [[package]]
 name = "hbvm"
 version = "0.1.0"
 dependencies = [
+ "delegate",
  "hashbrown",
+ "hbbytecode",
  "log",
+ "paste",
+ "static_assertions",
+]
+
+[[package]]
+name = "lasso"
+version = "0.7.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "4644821e1c3d7a560fe13d842d13f587c07348a1a05d3a797152d41c90c56df2"
+dependencies = [
+ "hashbrown",
 ]
 
 [[package]]
@@ -49,12 +95,108 @@ dependencies = [
  "cfg-if",
 ]
 
+[[package]]
+name = "logos"
+version = "0.13.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "c000ca4d908ff18ac99b93a062cb8958d331c3220719c52e77cb19cc6ac5d2c1"
+dependencies = [
+ "logos-derive",
+]
+
+[[package]]
+name = "logos-codegen"
+version = "0.13.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "dc487311295e0002e452025d6b580b77bb17286de87b57138f3b5db711cded68"
+dependencies = [
+ "beef",
+ "fnv",
+ "proc-macro2",
+ "quote",
+ "regex-syntax",
+ "syn 2.0.18",
+]
+
+[[package]]
+name = "logos-derive"
+version = "0.13.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "dbfc0d229f1f42d790440136d941afd806bc9e949e2bcb8faa813b0f00d1267e"
+dependencies = [
+ "logos-codegen",
+]
+
 [[package]]
 name = "once_cell"
 version = "1.17.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "b7e5500299e16ebb147ae15a00a942af264cf3688f47923b8fc2cd5858f23ad3"
 
+[[package]]
+name = "paste"
+version = "1.0.12"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9f746c4065a8fa3fe23974dd82f15431cc8d40779821001404d10d2e79ca7d79"
+
+[[package]]
+name = "proc-macro2"
+version = "1.0.59"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "6aeca18b86b413c660b781aa319e4e2648a3e6f9eadc9b47e9038e6fe9f3451b"
+dependencies = [
+ "unicode-ident",
+]
+
+[[package]]
+name = "quote"
+version = "1.0.28"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1b9ab9c7eadfd8df19006f1cf1a4aed13540ed5cbc047010ece5826e10825488"
+dependencies = [
+ "proc-macro2",
+]
+
+[[package]]
+name = "regex-syntax"
+version = "0.6.29"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f162c6dd7b008981e4d40210aca20b4bd0f9b60ca9271061b07f78537722f2e1"
+
+[[package]]
+name = "static_assertions"
+version = "1.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a2eb9349b6444b326872e140eb1cf5e7c522154d69e7a0ffb0fb81c06b37543f"
+
+[[package]]
+name = "syn"
+version = "1.0.109"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "72b64191b275b66ffe2469e8af2c1cfe3bafa67b529ead792a6d0160888b4237"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "unicode-ident",
+]
+
+[[package]]
+name = "syn"
+version = "2.0.18"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "32d41677bcbe24c20c52e7c70b0d8db04134c5d1066bf98662e2871ad200ea3e"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "unicode-ident",
+]
+
+[[package]]
+name = "unicode-ident"
+version = "1.0.9"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b15811caf2415fb889178633e7724bad2509101cde276048e013b9def5e51fa0"
+
 [[package]]
 name = "version_check"
 version = "0.9.4"

Cargo.toml

@@ -1,2 +1,2 @@
 [workspace]
-members = ["hbvm", "compiler"]
+members = ["hbasm", "hbbytecode", "hbvm"]

DESIGN_DOC.md

@@ -1,28 +0,0 @@
-# Math operations
-```
-MATH_OP
-    Add
-    Sub
-    Mul
-    Div
-    Mod
-```
-```
-MATH_TYPE
-    Unsigned
-    Signed
-    FloatingPoint
-```
-
-```
-MATH_OP_SIDES
-    Register Constant
-    Register Register
-    Constant Constant
-    Constant Register
-```
-`[MATH_OP] [MATH_OP_SIDES] [MATH_TYPE] [IMM_LHS] [IMM_RHS] [REG]`
-
-
-
-

compiler/Cargo.toml

@@ -1,8 +0,0 @@
-[package]
-name = "compiler"
-version = "0.1.0"
-edition = "2021"
-
-# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
-
-[dependencies]

compiler/src/main.rs

@@ -1,5 +0,0 @@
-fn main() {
-    let prog = "load 1, A0
-    jump 0";
-    println!("Hello, world!");
-}

hbasm/Cargo.toml

@@ -0,0 +1,14 @@
+[package]
+name = "hbasm"
+version = "0.1.0"
+edition = "2021"
+
+[dependencies]
+hbbytecode = { path = "../hbbytecode" }
+lasso      = "0.7"
+paste      = "1.0"
+
+[dependencies.logos]
+version = "0.13"
+default-features = false
+features = ["export_derive"]

hbasm/src/lib.rs

@@ -0,0 +1,269 @@
+use std::collections::HashMap;
+use {
+    lasso::{Rodeo, Spur},
+    logos::{Lexer, Logos, Span},
+    std::fmt::{Display, Formatter},
+};
+
+macro_rules! tokendef {
+    ($($opcode:literal),* $(,)?) => {
+        paste::paste! {
+            #[derive(Clone, Copy, Debug, PartialEq, Eq, Logos)]
+            #[logos(extras = Rodeo)]
+            #[logos(skip r"[ \t\f]+")]
+            #[logos(skip r"-- .*")]
+            pub enum Token {
+                $(#[token($opcode, |_| hbbytecode::opcode::[<$opcode:upper>])])*
+                OpCode(u8),
+
+                #[regex("[0-9]+", |l| l.slice().parse().ok())]
+                #[regex(
+                    "-[0-9]+",
+                    |lexer| {
+                        Some(u64::from_ne_bytes(lexer.slice().parse::<i64>().ok()?.to_ne_bytes()))
+                    },
+                )] Integer(u64),
+
+                #[regex(
+                    "r[0-9]+",
+                    |lexer| match lexer.slice()[1..].parse() {
+                        Ok(n) => Some(n),
+                        _ => None
+                    },
+                )] Register(u8),
+
+                #[regex(
+                    r"\p{XID_Start}\p{XID_Continue}*:",
+                    |lexer| lexer.extras.get_or_intern(&lexer.slice()[..lexer.slice().len() - 1]),
+                )] Label(Spur),
+
+                #[regex(
+                    r"\p{XID_Start}\p{XID_Continue}*",
+                    |lexer| lexer.extras.get_or_intern(lexer.slice()),
+                )] Symbol(Spur),
+
+                #[token("\n")]
+                #[token(";")] ISep,
+                #[token(",")] PSep,
+            }
+        }
+    };
+}
+
+#[rustfmt::skip]
+tokendef![
+    "nop", "add", "sub", "mul", "and", "or", "xor", "sl", "sr", "srs", "cmp", "cmpu",
+    "dir", "neg", "not", "addi", "muli", "andi", "ori", "xori", "sli", "sri", "srsi",
+    "cmpi", "cmpui", "cp", "swa", "li", "ld", "st", "bmc", "brc", "jmp", "jeq", "jne",
+    "jlt", "jgt", "jltu", "jgtu", "ecall", "addf", "mulf", "dirf", "addfi", "mulfi",
+];
+
+#[derive(Copy, Clone, Debug, PartialEq, Eq)]
+pub enum ErrorKind {
+    UnexpectedToken,
+    InvalidToken,
+    UnexpectedEnd,
+    InvalidSymbol,
+}
+
+#[derive(Clone, Debug, PartialEq, Eq)]
+pub struct Error {
+    pub kind: ErrorKind,
+    pub span: Span,
+}
+
+impl Display for Error {
+    fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
+        write!(f, "Error {:?} at {:?}", self.kind, self.span)
+    }
+}
+
+impl std::error::Error for Error {}
+
+macro_rules! expect_matches {
+    ($self:expr, $($pat:pat),* $(,)?) => {$(
+        let $pat = $self.next()?
+            else { return Err(ErrorKind::UnexpectedToken) };
+    )*}
+}
+
+pub fn assembly(code: &str, buf: &mut Vec<u8>) -> Result<(), Error> {
+    struct Assembler<'a> {
+        lexer: Lexer<'a, Token>,
+        buf: &'a mut Vec<u8>,
+        label_map: HashMap<Spur, u64>,
+        to_sub_label: HashMap<usize, Spur>,
+    }
+
+    impl<'a> Assembler<'a> {
+        fn next(&mut self) -> Result<Token, ErrorKind> {
+            match self.lexer.next() {
+                Some(Ok(t)) => Ok(t),
+                Some(Err(())) => Err(ErrorKind::InvalidToken),
+                None => Err(ErrorKind::UnexpectedEnd),
+            }
+        }
+
+        fn assemble(&mut self) -> Result<(), ErrorKind> {
+            use hbbytecode::opcode::*;
+            loop {
+                match self.lexer.next() {
+                    Some(Ok(Token::OpCode(op))) => {
+                        self.buf.push(op);
+                        match op {
+                            NOP | ECALL => Ok(()),
+                            DIR | DIRF => {
+                                expect_matches!(
+                                    self,
+                                    Token::Register(r0),
+                                    Token::PSep,
+                                    Token::Register(r1),
+                                    Token::PSep,
+                                    Token::Register(r2),
+                                    Token::PSep,
+                                    Token::Register(r3),
+                                );
+                                self.buf.extend([r0, r1, r2, r3]);
+                                Ok(())
+                            }
+                            ADD..=CMPU | ADDF..=MULF => {
+                                expect_matches!(
+                                    self,
+                                    Token::Register(r0),
+                                    Token::PSep,
+                                    Token::Register(r1),
+                                    Token::PSep,
+                                    Token::Register(r2),
+                                );
+                                self.buf.extend([r0, r1, r2]);
+                                Ok(())
+                            }
+                            BRC => {
+                                expect_matches!(
+                                    self,
+                                    Token::Register(r0),
+                                    Token::PSep,
+                                    Token::Register(r1),
+                                    Token::PSep,
+                                    Token::Integer(count),
+                                );
+                                self.buf.extend([
+                                    r0,
+                                    r1,
+                                    u8::try_from(count).map_err(|_| ErrorKind::UnexpectedToken)?,
+                                ]);
+                                Ok(())
+                            }
+                            NEG..=NOT | CP..=SWA => {
+                                expect_matches!(
+                                    self,
+                                    Token::Register(r0),
+                                    Token::PSep,
+                                    Token::Register(r1),
+                                );
+                                self.buf.extend([r0, r1]);
+                                Ok(())
+                            }
+                            LI | JMP => {
+                                expect_matches!(self, Token::Register(r0), Token::PSep);
+                                self.buf.push(r0);
+                                self.insert_imm()?;
+                                Ok(())
+                            }
+                            ADDI..=CMPUI | BMC | JEQ..=JGTU | ADDFI..=MULFI => {
+                                expect_matches!(
+                                    self,
+                                    Token::Register(r0),
+                                    Token::PSep,
+                                    Token::Register(r1),
+                                    Token::PSep,
+                                );
+                                self.buf.extend([r0, r1]);
+                                self.insert_imm()?;
+                                Ok(())
+                            }
+                            LD..=ST => {
+                                expect_matches!(
+                                    self,
+                                    Token::Register(r0),
+                                    Token::PSep,
+                                    Token::Register(r1),
+                                    Token::PSep,
+                                    Token::Integer(offset),
+                                    Token::PSep,
+                                    Token::Integer(len),
+                                );
+                                self.buf.extend([r0, r1]);
+                                self.buf.extend(offset.to_le_bytes());
+                                self.buf.extend(
+                                    u16::try_from(len)
+                                        .map_err(|_| ErrorKind::InvalidToken)?
+                                        .to_le_bytes(),
+                                );
+                                Ok(())
+                            }
+                            _ => unreachable!(),
+                        }?;
+                        match self.next() {
+                            Ok(Token::ISep) => (),
+                            Ok(_) => return Err(ErrorKind::UnexpectedToken),
+                            Err(ErrorKind::UnexpectedEnd) => return Ok(()),
+                            Err(e) => return Err(e),
+                        }
+                    }
+                    Some(Ok(Token::Label(lbl))) => {
+                        self.label_map.insert(lbl, self.buf.len() as u64);
+                    }
+                    Some(Ok(Token::ISep)) => (),
+                    Some(Ok(_)) => return Err(ErrorKind::UnexpectedToken),
+                    Some(Err(())) => return Err(ErrorKind::InvalidToken),
+                    None => return Ok(()),
+                }
+            }
+        }
+
+        fn link_local_syms(&mut self) -> Result<(), ErrorKind> {
+            for (ix, sym) in &self.to_sub_label {
+                self.label_map
+                    .get(sym)
+                    .ok_or(ErrorKind::InvalidSymbol)?
+                    .to_le_bytes()
+                    .iter()
+                    .enumerate()
+                    .for_each(|(i, b)| {
+                        self.buf[ix + i] = *b;
+                    });
+            }
+
+            Ok(())
+        }
+
+        fn insert_imm(&mut self) -> Result<(), ErrorKind> {
+            let imm = match self.next()? {
+                Token::Integer(i) => i.to_le_bytes(),
+                Token::Symbol(s) => {
+                    self.to_sub_label.insert(self.buf.len(), s);
+                    [0; 8]
+                }
+                _ => return Err(ErrorKind::UnexpectedToken),
+            };
+            self.buf.extend(imm);
+            Ok(())
+        }
+    }
+
+    let mut asm = Assembler {
+        lexer: Token::lexer(code),
+        label_map: Default::default(),
+        to_sub_label: Default::default(),
+        buf,
+    };
+
+    asm.assemble().map_err(|kind| Error {
+        kind,
+        span: asm.lexer.span(),
+    })?;
+
+    asm.link_local_syms()
+        .map_err(|kind| Error { kind, span: 0..0 })
+}

hbasm/src/main.rs

@@ -0,0 +1,21 @@
+use std::{
+    error::Error,
+    io::{stdin, stdout, Read, Write},
+};
+
+fn main() -> Result<(), Box<dyn Error>> {
+    let mut code = String::new();
+    stdin().read_to_string(&mut code)?;
+
+    let mut buf = vec![];
+    if let Err(e) = hbasm::assembly(&code, &mut buf) {
+        eprintln!(
+            "Error {:?} at {:?} (`{}`)",
+            e.kind,
+            e.span.clone(),
+            &code[e.span],
+        );
+    }
+    stdout().write_all(&buf)?;
+    Ok(())
+}

hbbytecode/Cargo.toml

@@ -0,0 +1,6 @@
+[package]
+name = "hbbytecode"
+version = "0.1.0"
+edition = "2021"
+
+[dependencies]

hbbytecode/hbbytecode.h

@@ -0,0 +1,60 @@
+/* HoleyBytes Bytecode representation in C
+ * Requires C23 compiler or better
+ */
+
+#pragma once
+#include <assert.h>
+#include <stdint.h>
+
+typedef enum hbbc_Opcode: uint8_t {
+    hbbc_Op_NOP, hbbc_Op_ADD, hbbc_Op_MUL, hbbc_Op_AND, hbbc_Op_OR, hbbc_Op_XOR, hbbc_Op_SL,
+    hbbc_Op_SR, hbbc_Op_SRS, hbbc_Op_CMP, hbbc_Op_CMPU, hbbc_Op_DIR, hbbc_Op_NEG, hbbc_Op_NOT,
+    hbbc_Op_ADDI, hbbc_Op_MULI, hbbc_Op_ANDI, hbbc_Op_ORI, hbbc_Op_XORI, hbbc_Op_SLI, hbbc_Op_SRI,
+    hbbc_Op_SRSI, hbbc_Op_CMPI, hbbc_Op_CMPUI, hbbc_Op_CP, hbbc_Op_SWA, hbbc_Op_LI, hbbc_Op_LD,
+    hbbc_Op_ST, hbbc_Op_BMC, hbbc_Op_BRC, hbbc_Op_JMP, hbbc_Op_JEQ, hbbc_Op_JNE, hbbc_Op_JLT,
+    hbbc_Op_JGT, hbbc_Op_JLTU, hbbc_Op_JGTU, hbbc_Op_ECALL, hbbc_Op_ADDF, hbbc_Op_MULF,
+    hbbc_Op_DIRF, hbbc_Op_ADDFI, hbbc_Op_MULFI,
+} hbbc_Opcode;
+
+static_assert(sizeof(hbbc_Opcode) == 1);
+
+#pragma pack(push, 1)
+typedef struct hbbc_ParamBBBB
+    { uint8_t _0; uint8_t _1; uint8_t _2; uint8_t _3; }
+    hbbc_ParamBBBB;
+    static_assert(sizeof(hbbc_ParamBBBB) == 4);
+
+typedef struct hbbc_ParamBBB
+    { uint8_t _0; uint8_t _1; uint8_t _2; }
+    hbbc_ParamBBB;
+    static_assert(sizeof(hbbc_ParamBBB) == 3);
+
+typedef struct hbbc_ParamBBDH
+    { uint8_t _0; uint8_t _1; uint64_t _2; uint16_t _3; }
+    hbbc_ParamBBDH;
+    static_assert(sizeof(hbbc_ParamBBDH) == 12);
+
+typedef struct hbbc_ParamBBDB
+    { uint8_t _0; uint8_t _1; uint64_t _2; uint8_t _3; }
+    hbbc_ParamBBDB;
+    static_assert(sizeof(hbbc_ParamBBDB) == 11);
+
+typedef struct hbbc_ParamBBD
+    { uint8_t _0; uint8_t _1; uint64_t _2; }
+    hbbc_ParamBBD;
+    static_assert(sizeof(hbbc_ParamBBD) == 10);
+
+typedef struct hbbc_ParamBB
+    { uint8_t _0; uint8_t _1; }
+    hbbc_ParamBB;
+    static_assert(sizeof(hbbc_ParamBB) == 2);
+
+typedef struct hbbc_ParamBD
+    { uint8_t _0; uint64_t _1; }
+    hbbc_ParamBD;
+    static_assert(sizeof(hbbc_ParamBD) == 9);
+
+typedef uint64_t hbbc_ParamD;
+    static_assert(sizeof(hbbc_ParamD) == 8);
+
+#pragma pack(pop)

hbbytecode/src/lib.rs

@@ -0,0 +1,106 @@
+#![no_std]
+
+macro_rules! constmod {
+    ($vis:vis $mname:ident($repr:ty) {
+        $(#![doc = $mdoc:literal])?
+        $($cname:ident = $val:expr $(,$doc:literal)?;)*
+    }) => {
+        $(#[doc = $mdoc])?
+        $vis mod $mname {
+            $(
+                $(#[doc = $doc])?
+                pub const $cname: $repr = $val;
+            )*
+        }
+    };
+}
+
+constmod!(pub opcode(u8) {
+    //! Opcode constant module
+
+    NOP = 0, "N; Do nothing";
+
+    ADD  = 1,  "BBB; #0 ← #1 + #2";
+    SUB  = 2,  "BBB; #0 ← #1 - #2";
+    MUL  = 3,  "BBB; #0 ← #1 × #2";
+    AND  = 4,  "BBB; #0 ← #1 & #2";
+    OR   = 5,  "BBB; #0 ← #1 | #2";
+    XOR  = 6,  "BBB; #0 ← #1 ^ #2";
+    SL   = 7,  "BBB; #0 ← #1 « #2";
+    SR   = 8,  "BBB; #0 ← #1 » #2";
+    SRS  = 9,  "BBB; #0 ← #1 » #2 (signed)";
+    CMP  = 10, "BBB; #0 ← #1 <=> #2";
+    CMPU = 11, "BBB; #0 ← #1 <=> #2 (unsigned)";
+    DIR  = 12, "BBBB; #0 ← #2 / #3, #1 ← #2 % #3";
+    NEG  = 13, "BB; #0 ← ~#1";
+    NOT  = 14, "BB; #0 ← !#1";
+
+    ADDI  = 15, "BBD; #0 ← #1 + imm #2";
+    MULI  = 16, "BBD; #0 ← #1 × imm #2";
+    ANDI  = 17, "BBD; #0 ← #1 & imm #2";
+    ORI   = 18, "BBD; #0 ← #1 | imm #2";
+    XORI  = 19, "BBD; #0 ← #1 ^ imm #2";
+    SLI   = 20, "BBD; #0 ← #1 « imm #2";
+    SRI   = 21, "BBD; #0 ← #1 » imm #2";
+    SRSI  = 22, "BBD; #0 ← #1 » imm #2 (signed)";
+    CMPI  = 23, "BBD; #0 ← #1 <=> imm #2";
+    CMPUI = 24, "BBD; #0 ← #1 <=> imm #2 (unsigned)";
+
+    CP  = 25, "BB; Copy #0 ← #1";
+    SWA = 26, "BB; Swap #0 and #1";
+    LI  = 27, "BD; #0 ← imm #1";
+    LD  = 28, "BBDB; #0 ← [#1 + imm #3], imm #4 bytes, overflowing";
+    ST  = 29, "BBDB; [#1 + imm #3] ← #0, imm #4 bytes, overflowing";
+    BMC = 30, "BBD; [#0] ← [#1], imm #2 bytes";
+    BRC = 31, "BBB; #0 ← #1, imm #2 registers";
+
+    JMP   = 32, "BD;  Unconditional jump [#0 + imm #1]";
+    JEQ   = 33, "BBD; if #0 = #1 → jump imm #2";
+    JNE   = 34, "BBD; if #0 ≠ #1 → jump imm #2";
+    JLT   = 35, "BBD; if #0 < #1 → jump imm #2";
+    JGT   = 36, "BBD; if #0 > #1 → jump imm #2";
+    JLTU  = 37, "BBD; if #0 < #1 → jump imm #2 (unsigned)";
+    JGTU  = 38, "BBD; if #0 > #1 → jump imm #2 (unsigned)";
+    ECALL = 39, "N; Issue system call";
+
+    ADDF  = 40, "BBB; #0 ← #1 +. #2";
+    MULF  = 41, "BBB; #0 ← #1 +. #2";
+    DIRF  = 42, "BBBB; #0 ← #2 / #3, #1 ← #2 % #3";
+
+    ADDFI = 43, "BBD; #0 ← #1 +. imm #2";
+    MULFI = 44, "BBD; #0 ← #1 *. imm #2";
+});
+
+#[repr(packed)]
+pub struct ParamBBBB(pub u8, pub u8, pub u8, pub u8);
+
+#[repr(packed)]
+pub struct ParamBBB(pub u8, pub u8, pub u8);
+
+#[repr(packed)]
+pub struct ParamBBDH(pub u8, pub u8, pub u64, pub u16);
+
+#[repr(packed)]
+pub struct ParamBBDB(pub u8, pub u8, pub u64, pub u8);
+
+#[repr(packed)]
+pub struct ParamBBD(pub u8, pub u8, pub u64);
+
+#[repr(packed)]
+pub struct ParamBB(pub u8, pub u8);
+
+#[repr(packed)]
+pub struct ParamBD(pub u8, pub u64);
+
+/// # Safety
+/// Has to be valid to be decoded from bytecode.
+pub unsafe trait OpParam {}
+unsafe impl OpParam for ParamBBBB {}
+unsafe impl OpParam for ParamBBB {}
+unsafe impl OpParam for ParamBBDB {}
+unsafe impl OpParam for ParamBBDH {}
+unsafe impl OpParam for ParamBBD {}
+unsafe impl OpParam for ParamBB {}
+unsafe impl OpParam for ParamBD {}
+unsafe impl OpParam for u64 {}
+unsafe impl OpParam for () {}

hbvm/Cargo.toml

@@ -3,6 +3,13 @@ name = "hbvm"
 version = "0.1.0"
 edition = "2021"
 
+[profile.release]
+lto = true
+
 [dependencies]
-log = "*"
-hashbrown = "0.13.2"
+delegate          = "0.9"
+hashbrown         = "0.13"
+hbbytecode.path   = "../hbbytecode"
+log               = "0.4"
+paste             = "1.0"
+static_assertions = "1.0"

hbvm/src/bytecode/mod.rs

@@ -1,2 +0,0 @@
-pub mod ops;
-pub mod types;

hbvm/src/bytecode/ops.rs

@@ -1,68 +0,0 @@
-#[repr(u8)]
-pub enum Operations {
-    NOP = 0,
-
-    ADD = 1,
-    SUB = 2,
-    MUL = 3,
-    DIV = 4,
-    MOD = 5,
-
-    AND = 6,
-    OR = 7,
-    XOR = 8,
-    NOT = 9,
-
-    // LOADs a memory address/constant into a register
-    LOAD = 15,
-    // STOREs a register/constant into a memory address
-    STORE = 16,
-
-    MapPage = 17,
-    UnmapPage = 18,
-
-    // SHIFT LEFT 16 A0
-    Shift = 20,
-
-    JUMP = 100,
-    JumpCond = 101,
-    RET = 103,
-
-    EnviromentCall = 255,
-}
-
-pub enum PageMapTypes {
-    // Have the host make a new VMPage
-    VMPage = 0,
-    // Ask the host to map a RealPage into memory
-    RealPage = 1,
-}
-
-pub enum MathOpSubTypes {
-    Unsigned = 0,
-    Signed = 1,
-    FloatingPoint = 2,
-}
-
-pub enum MathOpSides {
-    RegisterConstant = 0,
-    RegisterRegister = 1,
-    ConstantConstant = 2,
-    ConstantRegister = 3,
-}
-
-pub enum RWSubTypes {
-    AddrToReg = 0,
-    RegToAddr,
-    ConstToReg,
-    ConstToAddr,
-}
-
-pub enum JumpConditionals {
-    Equal = 0,
-    NotEqual = 1,
-    LessThan = 2,
-    LessThanOrEqualTo = 3,
-    GreaterThan = 4,
-    GreaterThanOrEqualTo = 5,
-}

hbvm/src/bytecode/types.rs

@@ -1,9 +0,0 @@
-
-pub const CONST_U8: u8 = 0x00;
-pub const CONST_I8: i8 = 0x01;
-
-pub const CONST_U64: u8 = 0x02;
-pub const CONST_I64: u8 = 0x03;
-pub const CONST_F64: u8 = 0x04;
-
-pub const ADDRESS: u8 = 0x05;

hbvm/src/engine/call_stack.rs

@@ -1,6 +0,0 @@
-use alloc::vec::Vec;
-
-pub type CallStack = Vec<FnCall>;
-pub struct FnCall {
-    pub ret: usize,
-}

hbvm/src/engine/config.rs

@@ -1,13 +0,0 @@
-pub struct EngineConfig {
-    pub call_stack_depth: usize,
-    pub quantum: u32,
-}
-
-impl EngineConfig {
-    pub fn default() -> Self {
-        Self {
-            call_stack_depth: 32,
-            quantum: 0,
-        }
-    }
-}

hbvm/src/engine/enviroment_calls.rs

@@ -1,3 +0,0 @@
-use super::Engine;
-
-pub type EnviromentCall = fn(&mut Engine) -> Result<&mut Engine, u64>;

hbvm/src/engine/mod.rs

@@ -1,102 +0,0 @@
-use log::info;
-
-pub mod call_stack;
-pub mod config;
-pub mod enviroment_calls;
-pub mod regs;
-#[cfg(test)]
-pub mod tests;
-
-use {
-    self::call_stack::CallStack,
-    crate::{engine::enviroment_calls::EnviromentCall, memory, HaltStatus, RuntimeErrors},
-    alloc::vec::Vec,
-    config::EngineConfig,
-    log::trace,
-    regs::Registers,
-};
-
-// pub const PAGE_SIZE: usize = 8192;
-
-pub struct RealPage {
-    pub ptr: *mut u8,
-}
-
-#[derive(Debug, Clone, Copy)]
-pub struct VMPage {
-    pub data: [u8; 8192],
-}
-impl Default for VMPage {
-    fn default() -> Self {
-        Self {
-            data: [0; 4096 * 2],
-        }
-    }
-}
-
-pub enum Page {
-    VMPage(VMPage),
-    RealPage(RealPage),
-}
-impl Page {
-    pub fn data(&self) -> [u8; 4096 * 2] {
-        match self {
-            Page::VMPage(vmpage) => vmpage.data,
-            Page::RealPage(_) => {
-                unimplemented!("Memmapped hw page not yet supported")
-            }
-        }
-    }
-}
-
-pub fn empty_enviroment_call(engine: &mut Engine) -> Result<&mut Engine, u64> {
-    trace!("Registers {:?}", engine.registers);
-    Err(0)
-}
-
-pub struct Engine {
-    pub pc: usize,
-    pub program: Vec<u8>,
-    pub registers: Registers,
-    pub config: EngineConfig,
-
-    /// BUG: This DOES NOT account for overflowing
-    pub last_timer_count: u32,
-    pub timer_callback: Option<fn() -> u32>,
-    pub memory: memory::Memory,
-    pub enviroment_call_table: [Option<EnviromentCall>; 256],
-    pub call_stack: CallStack,
-}
-
-impl Engine {
-    pub fn set_timer_callback(&mut self, func: fn() -> u32) {
-        self.timer_callback = Some(func);
-    }
-}
-
-impl Engine {
-    pub fn new(program: Vec<u8>) -> Self {
-        let mut mem = memory::Memory::new();
-        for (addr, byte) in program.clone().into_iter().enumerate() {
-            let _ = mem.set_addr8(addr as u64, byte);
-        }
-        trace!("{:?}", mem.read_addr8(0));
-        let ecall_table: [Option<EnviromentCall>; 256] = [None; 256];
-        Self {
-            pc: 0,
-            program,
-            registers: Registers::default(),
-            config: EngineConfig::default(),
-            last_timer_count: 0,
-            timer_callback: None,
-            enviroment_call_table: ecall_table,
-            memory: mem,
-            call_stack: Vec::new(),
-        }
-    }
-
-    pub fn dump(&self) {}
-    pub fn run(&mut self) -> Result<HaltStatus, RuntimeErrors> {
-        Ok(HaltStatus::Running)
-    }
-}

hbvm/src/engine/regs.rs

@@ -1,66 +0,0 @@
-use core::{
-    fmt::Debug,
-    ops::{Index, IndexMut},
-};
-
-#[derive(Debug, Clone, Copy)]
-pub struct Registers([Value; 60]);
-
-impl Index<u8> for Registers {
-    type Output = Value;
-
-    #[inline]
-    fn index(&self, index: u8) -> &Self::Output {
-        &self.0[index as usize]
-    }
-}
-
-impl IndexMut<u8> for Registers {
-    #[inline]
-    fn index_mut(&mut self, index: u8) -> &mut Self::Output {
-        &mut self.0[index as usize]
-    }
-}
-
-impl Default for Registers {
-    fn default() -> Self {
-        Self([Value { i: 0 }; 60])
-    }
-}
-
-/// # Safety
-/// The macro invoker shall make sure that byte reinterpret-cast
-/// won't cause undefined behaviour.
-macro_rules! value_def {
-    ($($fname:ident : $fty:ident, $getter:ident);* $(;)?) => {
-        #[derive(Clone, Copy)]
-        pub union Value {
-            $($fname: $fty),*
-        }
-
-        impl Value {$(
-            #[inline]
-            pub fn $getter(&self) -> $fty {
-                unsafe { self.$fname }
-            }
-        )*}
-
-        $(impl From<$fty> for Value {
-            #[inline]
-            fn from($fname: $fty) -> Self {
-                Self { $fname }
-            }
-        })*
-    }
-}
-
-value_def! {
-    i: u64, int;
-    f: f64, float;
-}
-
-impl Debug for Value {
-    fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
-        self.int().fmt(f)
-    }
-}

hbvm/src/engine/tests/mod.rs

@@ -1,125 +0,0 @@
-use {
-    super::Engine,
-    crate::{HaltStatus, RuntimeErrors},
-    alloc::vec,
-    RuntimeErrors::*,
-};
-
-#[test]
-fn invalid_program() {
-    let prog = vec![1, 0];
-    let mut eng = Engine::new(prog);
-    let ret = eng.run();
-    assert_eq!(ret, Err(InvalidOpcodePair(1, 0)));
-}
-
-#[test]
-fn empty_program() {
-    let prog = vec![];
-    let mut eng = Engine::new(prog);
-    let ret = eng.run();
-    assert_eq!(ret, Ok(HaltStatus::Halted));
-}
-
-#[test]
-fn max_quantum_reached() {
-    let prog = vec![0, 0, 0, 0];
-    let mut eng = Engine::new(prog);
-    eng.set_timer_callback(|| {
-        return 1;
-    });
-    eng.config.quantum = 1;
-    let ret = eng.run();
-    assert_eq!(ret, Ok(HaltStatus::Running));
-}
-
-#[test]
-fn jump_out_of_bounds() {
-    use crate::bytecode::ops::Operations::JUMP;
-    let prog = vec![JUMP as u8, 0, 0, 0, 0, 0, 0, 1, 0];
-    let mut eng = Engine::new(prog);
-    let ret = eng.run();
-    assert_eq!(ret, Err(InvalidJumpAddress(256)));
-}
-
-#[test]
-fn invalid_system_call() {
-    let prog = vec![255, 0];
-    let mut eng = Engine::new(prog);
-    let ret = eng.run();
-    assert_eq!(ret, Err(InvalidSystemCall(0)));
-}
-
-#[test]
-fn add_u8() {
-    use crate::bytecode::ops::{MathOpSides::ConstantConstant, Operations::ADD};
-
-    let prog = vec![ADD as u8, ConstantConstant as u8, 100, 98, 0xA0];
-    let mut eng = Engine::new(prog);
-    let _ = eng.run();
-    assert_eq!(eng.registers.a0, 2);
-}
-
-#[test]
-fn sub_u8() {
-    use crate::bytecode::ops::Operations::SUB;
-
-    let prog = vec![SUB as u8];
-    let mut eng = Engine::new(prog);
-    let _ = eng.run();
-    assert_eq!(eng.registers.a0, 1);
-}
-#[test]
-fn mul_u8() {
-    use crate::bytecode::ops::{MathOpSides::ConstantConstant, Operations::MUL};
-
-    let prog = vec![MUL as u8, ConstantConstant as u8, 1, 2, 0xA0];
-    let mut eng = Engine::new(prog);
-    let _ = eng.run();
-    assert_eq!(eng.registers.a0, 2);
-}
-
-#[test]
-fn div_u8() {
-    use crate::bytecode::ops::Operations::DIV;
-
-    let prog = vec![DIV as u8];
-    let mut eng = Engine::new(prog);
-    let _ = eng.run();
-    assert_eq!(eng.registers.a0, 2);
-}
-
-#[test]
-fn set_register() {
-    let prog = alloc::vec![];
-    let mut eng = Engine::new(prog);
-    eng.set_register(0xA0, 1);
-    assert_eq!(eng.registers.a0, 1);
-}
-
-#[test]
-fn load_u8() {
-    use crate::bytecode::ops::{Operations::LOAD, RWSubTypes::AddrToReg};
-
-    let prog = vec![LOAD as u8, AddrToReg as u8, 0, 0, 0, 0, 0, 0, 1, 0, 0xA0];
-    let mut eng = Engine::new(prog);
-    let ret = eng.memory.set_addr8(256, 1);
-    assert_eq!(ret, Ok(()));
-    let _ = eng.run();
-    assert_eq!(eng.registers.a0, 1);
-}
-#[test]
-fn set_memory_8() {
-    let prog = vec![];
-    let mut eng = Engine::new(prog);
-    let ret = eng.memory.set_addr8(256, 1);
-    assert_eq!(ret, Ok(()));
-}
-
-#[test]
-fn set_memory_64() {
-    let prog = vec![];
-    let mut eng = Engine::new(prog);
-    let ret = eng.memory.set_addr64(256, 1);
-    assert_eq!(ret, Ok(()));
-}

hbvm/src/lib.rs

@@ -1,9 +1,8 @@
 #![no_std]
 extern crate alloc;
 
-pub mod bytecode;
-pub mod engine;
-pub mod memory;
+pub mod validate;
+pub mod vm;
 
 #[derive(Debug, PartialEq)]
 pub enum RuntimeErrors {

hbvm/src/main.rs

@@ -1,32 +1,26 @@
-use hbvm::{
-    bytecode::ops::{Operations::*},
-    engine::Engine,
-    RuntimeErrors, HaltStatus,
+use {
+    hbvm::{validate::validate, vm::Vm},
+    std::io::{stdin, Read},
 };
 
-fn main() -> Result<(), RuntimeErrors> {
-    // TODO: Grab program from cmdline
-    #[rustfmt::skip]
-        let prog: Vec<u8> = vec![
-            NOP as u8,            
-            JUMP as u8, 0, 0, 0, 0, 0, 0, 0, 0,
-        ];
-
-    let mut eng = Engine::new(prog);
-    // eng.set_timer_callback(time);
-    eng.enviroment_call_table[10] = Some(print_fn);
-    while eng.run()? != HaltStatus::Halted {}
-    eng.dump();
-    println!("{:#?}", eng.registers);
-
+fn main() -> Result<(), Box<dyn std::error::Error>> {
+    let mut prog = vec![];
+    stdin().read_to_end(&mut prog)?;
+    
+    if let Err(e) = validate(&prog) {
+        eprintln!("Program validation error: {e:?}");
+        return Ok(());
+    } else {
+        unsafe {
+            let mut vm = Vm::new_unchecked(&prog);
+            vm.memory.insert_test_page();
+            println!("Program interrupt: {:?}", vm.run());
+            println!("{:?}", vm.registers);
+        }
+    }
     Ok(())
 }
 
 pub fn time() -> u32 {
     9
 }
-
-pub fn print_fn(engine: &mut Engine) -> Result<&mut Engine, u64> {
-    println!("hello");
-    Ok(engine)
-}

hbvm/src/memory.rs

@@ -1,70 +0,0 @@
-use crate::engine::VMPage;
-
-use {
-    crate::{engine::Page, RuntimeErrors},
-    alloc::vec::Vec,
-    hashbrown::HashMap,
-    log::trace,
-};
-
-pub struct Memory {
-    inner: HashMap<u64, Page>,
-}
-
-impl Memory {
-    pub fn new() -> Self {
-        Self {
-            inner: HashMap::new(),
-        }
-        //
-    }
-
-    pub fn map_vec(&mut self, address: u64, vec: Vec<u8>) {
-        panic!("Mapping vectors into pages is not supported yet");
-    }
-}
-
-impl Memory {
-    pub fn read_addr8(&mut self, address: u64) -> Result<u8, RuntimeErrors> {
-        let (page, offset) = addr_to_page(address);
-        trace!("page {} offset {}", page, offset);
-        match self.inner.get(&page) {
-            Some(page) => {
-                let val = page.data()[offset as usize];
-                trace!("Value {}", val);
-                Ok(val)
-            }
-            None => {
-                trace!("page not mapped");
-                Err(RuntimeErrors::PageNotMapped(page))
-            }
-        }
-    }
-    pub fn read_addr64(&mut self, address: u64) -> u64 {
-        unimplemented!()
-    }
-
-    pub fn set_addr8(&mut self, address: u64, value: u8) -> Result<(), RuntimeErrors> {
-        let (page, offset) = addr_to_page(address);
-        let ret: Option<(&u64, &mut Page)> = self.inner.get_key_value_mut(&page);
-        match ret {
-            Some((_, page)) => {
-                page.data()[offset as usize] = value;
-            }
-            None => {
-                let mut pg = VMPage::default();
-                pg.data[offset as usize] = value;
-                self.inner.insert(page, Page::VMPage(pg));
-                trace!("Mapped page {}", page);
-            }
-        }
-        Ok(())
-    }
-    pub fn set_addr64(&mut self, address: u64, value: u64) -> Result<(), RuntimeErrors> {
-        unimplemented!()
-    }
-}
-
-fn addr_to_page(addr: u64) -> (u64, u64) {
-    (addr / 8192, addr % 8192)
-}

hbvm/src/validate.rs

@@ -0,0 +1,52 @@
+#[derive(Clone, Copy, Debug, PartialEq, Eq)]
+pub enum ErrorKind {
+    InvalidInstruction,
+    Unimplemented,
+    RegisterArrayOverflow,
+}
+
+#[derive(Clone, Copy, Debug, PartialEq, Eq)]
+pub struct Error {
+    pub kind: ErrorKind,
+    pub index: usize,
+}
+
+pub fn validate(mut program: &[u8]) -> Result<(), Error> {
+    use hbbytecode::opcode::*;
+
+    let start = program;
+    loop {
+        program = match program {
+            [] => return Ok(()),
+            [LD..=ST, reg, _, _, _, _, _, _, _, _, _, count, ..]
+                if usize::from(*reg) * 8 + usize::from(*count) > 2048 =>
+            {
+                return Err(Error {
+                    kind: ErrorKind::RegisterArrayOverflow,
+                    index: (program.as_ptr() as usize) - (start.as_ptr() as usize),
+                })
+            }
+            [BRC, src, dst, count, ..]
+                if src.checked_add(*count).is_none() || dst.checked_add(*count).is_none() =>
+            {
+                return Err(Error {
+                    kind: ErrorKind::RegisterArrayOverflow,
+                    index: (program.as_ptr() as usize) - (start.as_ptr() as usize),
+                })
+            }
+            [NOP | ECALL, rest @ ..]
+            | [DIR | DIRF, _, _, _, _, rest @ ..]
+            | [ADD..=CMPU | BRC | ADDF..=MULF, _, _, _, rest @ ..]
+            | [NEG..=NOT | CP..=SWA, _, _, rest @ ..]
+            | [LI | JMP, _, _, _, _, _, _, _, _, _, rest @ ..]
+            | [ADDI..=CMPUI | BMC | JEQ..=JGTU | ADDFI..=MULFI, _, _, _, _, _, _, _, _, _, _, rest @ ..]
+            | [LD..=ST, _, _, _, _, _, _, _, _, _, _, _, _, rest @ ..] => rest,
+            _ => {
+                return Err(Error {
+                    kind: ErrorKind::InvalidInstruction,
+                    index: (program.as_ptr() as usize) - (start.as_ptr() as usize),
+                })
+            }
+        }
+    }
+}

hbvm/src/vm/mem/mod.rs

@@ -0,0 +1,238 @@
+mod paging;
+
+use self::paging::{PageTable, Permission, PtEntry};
+use alloc::boxed::Box;
+
+#[derive(Clone, Debug)]
+pub struct Memory {
+    root_pt: *mut PageTable,
+}
+
+impl Default for Memory {
+    fn default() -> Self {
+        Self {
+            root_pt: Box::into_raw(Box::default()),
+        }
+    }
+}
+
+impl Drop for Memory {
+    fn drop(&mut self) {
+        let _ = unsafe { Box::from_raw(self.root_pt) };
+    }
+}
+
+impl Memory {
+    // HACK: Just for allocation testing, will be removed when proper memory interfaces
+    // implemented.
+    pub fn insert_test_page(&mut self) {
+        unsafe {
+            let mut entry = PtEntry::new(
+                {
+                    let layout = alloc::alloc::Layout::from_size_align_unchecked(4096, 4096);
+                    let ptr = alloc::alloc::alloc_zeroed(layout);
+                    if ptr.is_null() {
+                        alloc::alloc::handle_alloc_error(layout);
+                    }
+
+                    core::ptr::write_bytes(ptr, 69, 10);
+                    ptr.cast()
+                },
+                Permission::Write,
+            );
+
+            for _ in 0..4 {
+                let mut pt = Box::<PageTable>::default();
+                pt[0] = entry;
+                entry = PtEntry::new(Box::into_raw(pt) as _, Permission::Node);
+            }
+
+            self.root_pt_mut()[0] = entry;
+        }
+    }
+
+    /// Load value from an address
+    pub unsafe fn load(&self, addr: u64, target: *mut u8, count: usize) -> Result<(), AccessFault> {
+        self.memory_access(
+            addr,
+            target,
+            count,
+            |perm| {
+                matches!(
+                    perm,
+                    Permission::Readonly | Permission::Write | Permission::Exec
+                )
+            },
+            |src, dst, count| core::ptr::copy_nonoverlapping(src, dst, count),
+        )
+    }
+
+    /// Store value to an address
+    pub unsafe fn store(
+        &mut self,
+        addr: u64,
+        source: *const u8,
+        count: usize,
+    ) -> Result<(), AccessFault> {
+        self.memory_access(
+            addr,
+            source.cast_mut(),
+            count,
+            |perm| perm == Permission::Write,
+            |dst, src, count| core::ptr::copy_nonoverlapping(src, dst, count),
+        )
+    }
+
+    /// Copy a block of memory
+    pub unsafe fn block_copy(&mut self, src: u64, dst: u64, count: u64) -> Result<(), ()> {
+        /* let count = usize::try_from(count).expect("?conradluget a better CPU");
+
+        let mut srcs = PageSplitter::new(src, count, self.root_pt);
+        let mut dsts = PageSplitter::new(dst, count, self.root_pt);
+        let mut c_src = srcs.next().ok_or(())?;
+        let mut c_dst = dsts.next().ok_or(())?;
+
+        loop {
+            let min_size = c_src.size.min(c_dst.size);
+            unsafe {
+                core::ptr::copy(c_src.ptr, c_dst.ptr, min_size);
+            }
+
+            match (
+                match c_src.size.saturating_sub(min_size) {
+                    0 => srcs.next(),
+                    size => Some(PageSplitResult { size, ..c_src }),
+                },
+                match c_dst.size.saturating_sub(min_size) {
+                    0 => dsts.next(),
+                    size => Some(PageSplitResult { size, ..c_dst }),
+                },
+            ) {
+                (None, None) => return Ok(()),
+                (Some(src), Some(dst)) => (c_src, c_dst) = (src, dst),
+                _ => return Err(()),
+            }
+        } */
+
+        todo!("Block memory copy")
+    }
+
+    #[inline]
+    pub fn root_pt(&self) -> &PageTable {
+        unsafe { &*self.root_pt }
+    }
+
+    #[inline]
+    pub fn root_pt_mut(&mut self) -> &mut PageTable {
+        unsafe { &mut *self.root_pt }
+    }
+
+    fn memory_access(
+        &self,
+        src: u64,
+        mut dst: *mut u8,
+        len: usize,
+        permission_check: impl Fn(Permission) -> bool,
+        action: impl Fn(*mut u8, *mut u8, usize),
+    ) -> Result<(), AccessFault> {
+        for item in PageSplitter::new(src, len, self.root_pt) {
+            let PageSplitResult { ptr, size, perm } = item?;
+            if !permission_check(perm) {
+                return Err(AccessFault::Permission);
+            }
+
+            action(ptr, dst, size);
+            dst = unsafe { dst.add(size) };
+        }
+
+        Ok(())
+    }
+}
+
+#[derive(Debug)]
+struct PageSplitResult {
+    ptr: *mut u8,
+    size: usize,
+    perm: Permission,
+}
+
+struct PageSplitter {
+    addr: u64,
+    size: usize,
+    pagetable: *const PageTable,
+}
+
+impl PageSplitter {
+    pub const fn new(addr: u64, size: usize, pagetable: *const PageTable) -> Self {
+        Self {
+            addr,
+            size,
+            pagetable,
+        }
+    }
+}
+
+impl Iterator for PageSplitter {
+    type Item = Result<PageSplitResult, AccessFault>;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        if self.size == 0 {
+            return None;
+        }
+
+        let (base, perm, size, offset) = 'a: {
+            let mut current_pt = self.pagetable;
+            for lvl in (0..5).rev() {
+                unsafe {
+                    let entry = (*current_pt).get_unchecked(
+                        usize::try_from((self.addr >> (lvl * 9 + 12)) & ((1 << 9) - 1))
+                            .expect("?conradluget a better CPU"),
+                    );
+
+                    let ptr = entry.ptr();
+                    match entry.permission() {
+                        Permission::Empty => {
+                            return Some(Err(AccessFault::NoPage {
+                                addr: self.addr,
+                                remaining: self.size,
+                            }))
+                        }
+                        Permission::Node => current_pt = ptr as _,
+                        perm => {
+                            break 'a (
+                                ptr as *mut u8,
+                                perm,
+                                match lvl {
+                                    0 => 4096,
+                                    1 => 1024_usize.pow(2) * 2,
+                                    2 => 1024_usize.pow(3),
+                                    _ => return Some(Err(AccessFault::TooShallow)),
+                                },
+                                self.addr as usize & ((1 << (lvl * 9 + 12)) - 1),
+                            )
+                        }
+                    }
+                }
+            }
+            return Some(Err(AccessFault::TooDeep));
+        };
+
+        extern crate std;
+        let avail = (size - offset).clamp(0, self.size);
+        self.addr += size as u64;
+        self.size = self.size.saturating_sub(size);
+        std::dbg!(Some(Ok(PageSplitResult {
+            ptr: unsafe { base.add(offset) },
+            size: avail,
+            perm,
+        })))
+    }
+}
+
+#[derive(Clone, Copy, Debug, PartialEq, Eq)]
+pub enum AccessFault {
+    NoPage { addr: u64, remaining: usize },
+    Permission,
+    TooShallow,
+    TooDeep,
+}

hbvm/src/vm/mem/paging.rs

@@ -0,0 +1,101 @@
+use core::{
+    fmt::Debug,
+    mem::MaybeUninit,
+    ops::{Index, IndexMut},
+    slice::SliceIndex,
+};
+use delegate::delegate;
+
+#[derive(Clone, Copy, Debug, Default, PartialEq, Eq)]
+#[repr(u8)]
+pub enum Permission {
+    #[default]
+    Empty,
+    Node,
+    Readonly,
+    Write,
+    Exec,
+}
+
+#[derive(Clone, Copy, Default, PartialEq, Eq)]
+pub struct PtEntry(u64);
+impl PtEntry {
+    #[inline]
+    pub unsafe fn new(ptr: *mut PtPointedData, permission: Permission) -> Self {
+        Self(ptr as u64 | permission as u64)
+    }
+
+    #[inline]
+    pub fn permission(&self) -> Permission {
+        unsafe { core::mem::transmute(self.0 as u8 & 0b111) }
+    }
+
+    #[inline]
+    pub fn ptr(&self) -> *mut PtPointedData {
+        (self.0 & !((1 << 12) - 1)) as _
+    }
+}
+
+impl Debug for PtEntry {
+    fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
+        f.debug_struct("PtEntry")
+            .field("ptr", &self.ptr())
+            .field("permission", &self.permission())
+            .finish()
+    }
+}
+
+#[derive(Clone, Copy, Debug, PartialEq, Eq)]
+#[repr(align(4096))]
+pub struct PageTable([PtEntry; 512]);
+
+impl PageTable {
+    delegate!(to self.0 {
+        pub unsafe fn get<I>(&self, ix: I) -> Option<&I::Output>
+            where I: SliceIndex<[PtEntry]>;
+
+        pub unsafe fn get_mut<I>(&mut self, ix: I) -> Option<&mut I::Output>
+            where I: SliceIndex<[PtEntry]>;
+
+        pub unsafe fn get_unchecked<I>(&self, index: I) -> &I::Output
+            where I: SliceIndex<[PtEntry]>;
+
+        pub unsafe fn get_unchecked_mut<I>(&mut self, index: I) -> &mut I::Output
+            where I: SliceIndex<[PtEntry]>;
+    });
+}
+
+impl<Idx> Index<Idx> for PageTable
+where
+    Idx: SliceIndex<[PtEntry]>,
+{
+    type Output = Idx::Output;
+
+    #[inline(always)]
+    fn index(&self, index: Idx) -> &Self::Output {
+        &self.0[index]
+    }
+}
+
+impl<Idx> IndexMut<Idx> for PageTable
+where
+    Idx: SliceIndex<[PtEntry]>,
+{
+    #[inline(always)]
+    fn index_mut(&mut self, index: Idx) -> &mut Self::Output {
+        &mut self.0[index]
+    }
+}
+
+impl Default for PageTable {
+    fn default() -> Self {
+        Self(unsafe { MaybeUninit::zeroed().assume_init() })
+    }
+}
+
+#[derive(Clone, Copy)]
+#[repr(C, align(4096))]
+pub union PtPointedData {
+    pub pt: PageTable,
+    pub page: u8,
+}

hbvm/src/vm/mod.rs

@@ -0,0 +1,302 @@
+//! HoleyBytes Virtual Machine
+//!
+//! All unsafe code here should be sound, if input bytecode passes validation.
+
+// # General safety notice:
+// - Validation has to assure there is 256 registers (r0 - r255)
+// - Instructions have to be valid as specified (values and sizes)
+// - Mapped pages should be at least 4 KiB
+// - Yes, I am aware of the UB when jumping in-mid of instruction where
+//   the read byte corresponds to an instruction whose lenght exceets the
+//   program size. If you are (rightfully) worried about the UB, for now just
+//   append your program with 11 zeroes.
+
+use self::mem::AccessFault;
+
+mod mem;
+mod value;
+
+use {
+    crate::validate,
+    core::ops,
+    hbbytecode::{OpParam, ParamBB, ParamBBB, ParamBBBB, ParamBBD, ParamBBDH, ParamBD},
+    mem::Memory,
+    static_assertions::assert_impl_one,
+    value::Value,
+};
+
+macro_rules! param {
+    ($self:expr, $ty:ty) => {{
+        assert_impl_one!($ty: OpParam);
+        let data = $self
+            .program
+            .as_ptr()
+            .add($self.pc + 1)
+            .cast::<$ty>()
+            .read();
+        $self.pc += 1 + core::mem::size_of::<$ty>();
+        data
+    }};
+}
+
+macro_rules! binary_op {
+    ($self:expr, $ty:ident, $handler:expr) => {{
+        let ParamBBB(tg, a0, a1) = param!($self, ParamBBB);
+        $self.write_reg(
+            tg,
+            $handler(
+                Value::$ty(&$self.read_reg(a0)),
+                Value::$ty(&$self.read_reg(a1)),
+            )
+            .into(),
+        );
+    }};
+}
+
+macro_rules! binary_op_imm {
+    ($self:expr, $ty:ident, $handler:expr) => {{
+        let ParamBBD(tg, a0, imm) = param!($self, ParamBBD);
+        $self.write_reg(
+            tg,
+            $handler(Value::$ty(&$self.read_reg(a0)), Value::$ty(&imm.into())).into(),
+        );
+    }};
+}
+
+macro_rules! cond_jump {
+    ($self:expr, $ty:ident, $expected:ident) => {{
+        let ParamBBD(a0, a1, jt) = param!($self, ParamBBD);
+        if core::cmp::Ord::cmp(&$self.read_reg(a0).as_u64(), &$self.read_reg(a1).as_u64())
+            == core::cmp::Ordering::$expected
+        {
+            $self.pc = jt as usize;
+        }
+    }};
+}
+
+pub struct Vm<'a> {
+    pub registers: [Value; 256],
+    pub memory: Memory,
+    pc: usize,
+    program: &'a [u8],
+}
+
+impl<'a> Vm<'a> {
+    /// # Safety
+    /// Program code has to be validated
+    pub unsafe fn new_unchecked(program: &'a [u8]) -> Self {
+        Self {
+            registers: [Value::from(0_u64); 256],
+            memory: Default::default(),
+            pc: 0,
+            program,
+        }
+    }
+
+    pub fn new_validated(program: &'a [u8]) -> Result<Self, validate::Error> {
+        validate::validate(program)?;
+        Ok(unsafe { Self::new_unchecked(program) })
+    }
+
+    pub fn run(&mut self) -> HaltReason {
+        use hbbytecode::opcode::*;
+        loop {
+            let Some(&opcode) = self.program.get(self.pc)
+                else { return HaltReason::ProgramEnd };
+
+            unsafe {
+                match opcode {
+                    NOP => param!(self, ()),
+                    ADD => binary_op!(self, as_u64, u64::wrapping_add),
+                    SUB => binary_op!(self, as_u64, u64::wrapping_sub),
+                    MUL => binary_op!(self, as_u64, u64::wrapping_mul),
+                    AND => binary_op!(self, as_u64, ops::BitAnd::bitand),
+                    OR => binary_op!(self, as_u64, ops::BitOr::bitor),
+                    XOR => binary_op!(self, as_u64, ops::BitXor::bitxor),
+                    SL => binary_op!(self, as_u64, ops::Shl::shl),
+                    SR => binary_op!(self, as_u64, ops::Shr::shr),
+                    SRS => binary_op!(self, as_i64, ops::Shr::shr),
+                    CMP => {
+                        let ParamBBB(tg, a0, a1) = param!(self, ParamBBB);
+                        self.write_reg(
+                            tg,
+                            (self.read_reg(a0).as_i64().cmp(&self.read_reg(a1).as_i64()) as i64)
+                                .into(),
+                        );
+                    }
+                    CMPU => {
+                        let ParamBBB(tg, a0, a1) = param!(self, ParamBBB);
+                        self.write_reg(
+                            tg,
+                            (self.read_reg(a0).as_u64().cmp(&self.read_reg(a1).as_u64()) as i64)
+                                .into(),
+                        );
+                    }
+                    NOT => {
+                        let param = param!(self, ParamBB);
+                        self.write_reg(param.0, (!self.read_reg(param.1).as_u64()).into());
+                    }
+                    NEG => {
+                        let param = param!(self, ParamBB);
+                        self.write_reg(
+                            param.0,
+                            match self.read_reg(param.1).as_u64() {
+                                0 => 1_u64,
+                                _ => 0,
+                            }
+                            .into(),
+                        );
+                    }
+                    DIR => {
+                        let ParamBBBB(dt, rt, a0, a1) = param!(self, ParamBBBB);
+                        let a0 = self.read_reg(a0).as_u64();
+                        let a1 = self.read_reg(a1).as_u64();
+                        self.write_reg(dt, (a0.checked_div(a1).unwrap_or(u64::MAX)).into());
+                        self.write_reg(rt, (a0.checked_rem(a1).unwrap_or(u64::MAX)).into());
+                    }
+                    ADDI => binary_op_imm!(self, as_u64, ops::Add::add),
+                    MULI => binary_op_imm!(self, as_u64, ops::Mul::mul),
+                    ANDI => binary_op_imm!(self, as_u64, ops::BitAnd::bitand),
+                    ORI => binary_op_imm!(self, as_u64, ops::BitOr::bitor),
+                    XORI => binary_op_imm!(self, as_u64, ops::BitXor::bitxor),
+                    SLI => binary_op_imm!(self, as_u64, ops::Shl::shl),
+                    SRI => binary_op_imm!(self, as_u64, ops::Shr::shr),
+                    SRSI => binary_op_imm!(self, as_i64, ops::Shr::shr),
+                    CMPI => {
+                        let ParamBBD(tg, a0, imm) = param!(self, ParamBBD);
+                        self.write_reg(
+                            tg,
+                            (self.read_reg(a0).as_i64().cmp(&Value::from(imm).as_i64()) as i64)
+                                .into(),
+                        );
+                    }
+                    CMPUI => {
+                        let ParamBBD(tg, a0, imm) = param!(self, ParamBBD);
+                        self.write_reg(tg, (self.read_reg(a0).as_u64().cmp(&imm) as i64).into());
+                    }
+                    CP => {
+                        let param = param!(self, ParamBB);
+                        self.write_reg(param.0, self.read_reg(param.1));
+                    }
+                    SWA => {
+                        let ParamBB(src, dst) = param!(self, ParamBB);
+                        if src + dst != 0 {
+                            core::ptr::swap(
+                                self.registers.get_unchecked_mut(usize::from(src)),
+                                self.registers.get_unchecked_mut(usize::from(dst)),
+                            );
+                        }
+                    }
+                    LI => {
+                        let param = param!(self, ParamBD);
+                        self.write_reg(param.0, param.1.into());
+                    }
+                    LD => {
+                        let ParamBBDH(dst, base, off, count) = param!(self, ParamBBDH);
+                        let n: usize = match dst {
+                            0 => 1,
+                            _ => 0,
+                        };
+
+                        if let Err(e) = self.memory.load(
+                            self.read_reg(base).as_u64() + off + n as u64,
+                            self.registers.as_mut_ptr().add(usize::from(dst) + n).cast(),
+                            usize::from(count).saturating_sub(n),
+                        ) {
+                            return HaltReason::LoadAccessEx(e);
+                        }
+                    }
+                    ST => {
+                        let ParamBBDH(dst, base, off, count) = param!(self, ParamBBDH);
+                        if let Err(e) = self.memory.store(
+                            self.read_reg(base).as_u64() + off,
+                            self.registers.as_ptr().add(usize::from(dst)).cast(),
+                            count.into(),
+                        ) {
+                            return HaltReason::StoreAccessEx(e);
+                        }
+                    }
+                    BMC => {
+                        let ParamBBD(src, dst, count) = param!(self, ParamBBD);
+                        if self
+                            .memory
+                            .block_copy(
+                                self.read_reg(src).as_u64(),
+                                self.read_reg(dst).as_u64(),
+                                count,
+                            )
+                            .is_err()
+                        {
+                            todo!("Block memory copy fault");
+                        }
+                    }
+                    BRC => {
+                        let ParamBBB(src, dst, count) = param!(self, ParamBBB);
+                        core::ptr::copy(
+                            self.registers.get_unchecked(usize::from(src)),
+                            self.registers.get_unchecked_mut(usize::from(dst)),
+                            usize::from(count * 8),
+                        );
+                    }
+                    JMP => {
+                        let ParamBD(reg, offset) = param!(self, ParamBD);
+                        self.pc = (self.read_reg(reg).as_u64() + offset) as usize;
+                    }
+                    JEQ => cond_jump!(self, int, Equal),
+                    JNE => {
+                        let ParamBBD(a0, a1, jt) = param!(self, ParamBBD);
+                        if self.read_reg(a0).as_u64() != self.read_reg(a1).as_u64() {
+                            self.pc = jt as usize;
+                        }
+                    }
+                    JLT => cond_jump!(self, int, Less),
+                    JGT => cond_jump!(self, int, Greater),
+                    JLTU => cond_jump!(self, sint, Less),
+                    JGTU => cond_jump!(self, sint, Greater),
+                    ECALL => {
+                        param!(self, ());
+                        return HaltReason::Ecall;
+                    }
+                    ADDF => binary_op!(self, as_f64, ops::Add::add),
+                    MULF => binary_op!(self, as_f64, ops::Mul::mul),
+                    DIRF => {
+                        let ParamBBBB(dt, rt, a0, a1) = param!(self, ParamBBBB);
+                        let a0 = self.read_reg(a0).as_f64();
+                        let a1 = self.read_reg(a1).as_f64();
+                        self.write_reg(dt, (a0 / a1).into());
+                        self.write_reg(rt, (a0 % a1).into());
+                    }
+                    ADDFI => binary_op_imm!(self, as_f64, ops::Add::add),
+                    MULFI => binary_op_imm!(self, as_f64, ops::Mul::mul),
+                    op => return HaltReason::InvalidOpEx(op),
+                }
+            }
+        }
+    }
+
+    #[inline]
+    unsafe fn read_reg(&self, n: u8) -> Value {
+        if n == 0 {
+            0_u64.into()
+        } else {
+            *self.registers.get_unchecked(n as usize)
+        }
+    }
+
+    #[inline]
+    unsafe fn write_reg(&mut self, n: u8, value: Value) {
+        if n != 0 {
+            *self.registers.get_unchecked_mut(n as usize) = value;
+        }
+    }
+}
+
+#[derive(Copy, Clone, Debug, PartialEq, Eq)]
+#[repr(u8)]
+pub enum HaltReason {
+    ProgramEnd,
+    Ecall,
+    InvalidOpEx(u8),
+    LoadAccessEx(AccessFault),
+    StoreAccessEx(AccessFault),
+}

hbvm/src/vm/value.rs

@@ -0,0 +1,37 @@
+use core::fmt::Debug;
+
+macro_rules! value_def {
+    ($($ty:ident),* $(,)?) => {
+        #[derive(Copy, Clone)]
+        #[repr(packed)]
+        pub union Value {
+            $(pub $ty: $ty),*
+        }
+
+        paste::paste! {
+            impl Value {$(
+                #[inline]
+                pub fn [<as_ $ty>](&self) -> $ty {
+                    unsafe { self.$ty }
+                }
+            )*}
+        }
+
+        $(
+            impl From<$ty> for Value {
+                #[inline]
+                fn from(value: $ty) -> Self {
+                    Self { $ty: value }
+                }
+            }
+        )*
+    };
+}
+
+value_def!(u64, i64, f64);
+
+impl Debug for Value {
+    fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
+        self.as_u64().fmt(f)
+    }
+}

rust-toolchain

@@ -1 +0,0 @@
-nightly

spec.md

@@ -0,0 +1,272 @@
+# HoleyBytes ISA Specification
+
+# Bytecode format
+- All numbers are encoded little-endian
+- There is 256 registers, they are represented by a byte
+- Immediate values are 64 bit
+
+### Instruction encoding
+- Instruction parameters are packed (no alignment)
+- [opcode, …parameters…]
+
+### Instruction parameter types
+- B = Byte
+- D = Doubleword (64 bits)
+- H = Halfword (16 bits)
+
+| Name | Size    |
+|:----:|:--------|
+| BBBB | 32 bits |
+| BBB  | 24 bits |
+| BBDH | 96 bits |
+| BBDB | 88 bits |
+| BBD  | 80 bits |
+|  BB  | 16 bits |
+|  BD  | 72 bits |
+|  D   | 64 bits |
+|  N   | 0  bits |
+
+# Instructions
+- `#n`: register in parameter *n*
+- `imm #n`: for immediate in parameter *n*
+- `P ← V`: Set register P to value V
+- `[x]`: Address x
+
+## No-op
+- N type
+
+| Opcode | Name |   Action   |
+|:------:|:----:|:----------:|
+|   0    | NOP  | Do nothing |
+
+## Integer binary ops.
+- BBB type
+- `#0 ← #1 <op> #2`
+
+| Opcode | Name |         Action          |
+|:------:|:----:|:-----------------------:|
+|   1    | ADD  |    Wrapping addition    |
+|   2    | SUB  |  Wrapping subtraction   |
+|   3    | MUL  | Wrapping multiplication |
+|   4    | AND  |         Bitand          |
+|   5    |  OR  |          Bitor          |
+|   6    | XOR  |         Bitxor          |
+|   7    |  SL  | Unsigned left bitshift  |
+|   8    |  SR  | Unsigned right bitshift |
+|   9    | SRS  |  Signed right bitshift  |
+
+### Comparsion
+| Opcode | Name |       Action        |
+|:------:|:----:|:-------------------:|
+|   10   | CMP  |  Signed comparsion  |
+|   11   | CMPU | Unsigned comparsion |
+
+#### Comparsion table
+| #1 *op* #2 | Result |
+|:----------:|:------:|
+|     <      |   -1   |
+|     =      |   0    |
+|     >      |   1    |
+
+### Division-remainder
+- Type BBBB
+- In case of `#3` is zero, the resulting value is all-ones
+- `#0 ← #2 ÷ #3`
+- `#1 ← #2 % #3`
+
+| Opcode | Name |             Action              |
+|:------:|:----:|:-------------------------------:|
+|   12   | DIR  | Divide and remainder combinated |
+
+### Negations
+- Type BB
+- `#0 ← #1 <op> #2`
+
+| Opcode | Name |      Action      |
+|:------:|:----:|:----------------:|
+|   13   | NEG  |   Bit negation   |
+|   14   | NOT  | Logical negation |
+
+## Integer immediate binary ops.
+- Type BBD
+- `#0 ← #1 <op> imm #2`
+
+| Opcode | Name |         Action          |
+|:------:|:----:|:-----------------------:|
+|   15   | ADDI |    Wrapping addition    |
+|   16   | MULI |  Wrapping subtraction   |
+|   17   | ANDI |         Bitand          |
+|   18   | ORI  |          Bitor          |
+|   19   | XORI |         Bitxor          |
+|   20   | SLI  | Unsigned left bitshift  |
+|   21   | SRI  | Unsigned right bitshift |
+|   22   | SRSI |  Signed right bitshift  |
+
+### Comparsion
+- Comparsion is the same as when RRR type
+
+| Opcode | Name  |       Action        |
+|:------:|:-----:|:-------------------:|
+|   23   | CMPI  |  Signed comparsion  |
+|   24   | CMPUI | Unsigned comparsion |
+
+## Register value set / copy
+
+### Copy
+- Type BB
+- `#0 ← #1`
+
+| Opcode | Name | Action |
+|:------:|:----:|:------:|
+|   25   |  CP  |  Copy  |
+
+### Swap
+- Type BB
+- Swap #0 and #1
+
+| Opcode | Name | Action |
+|:------:|:----:|:------:|
+|   26   | SWA  |  Swap  |
+
+### Load immediate
+- Type BD
+- `#0 ← #1`
+
+| Opcode | Name |     Action     |
+|:------:|:----:|:--------------:|
+|   27   |  LI  | Load immediate |
+
+## Memory operations
+- Type BBDH
+- If loaded/store value exceeds one register size, continue accessing following registers
+
+### Load / Store
+| Opcode | Name |                 Action                  |
+|:------:|:----:|:---------------------------------------:|
+|   28   |  LD  | `#0 ← [#1 + imm #3], copy imm #4 bytes` |
+|   29   |  ST  | `[#1 + imm #3] ← #0, copy imm #4 bytes` |
+
+## Block copy
+- Block copy source and target can overlap
+
+### Memory copy
+- Type BBD
+
+| Opcode | Name |              Action              |
+|:------:|:----:|:--------------------------------:|
+|   30   | BMC  | `[#0] ← [#1], copy imm #2 bytes` |
+
+### Register copy
+- Type BBB
+- Copy a block a register to another location (again, overflowing to following registers)
+
+| Opcode | Name |              Action              |
+|:------:|:----:|:--------------------------------:|
+|   31   | BRC  | `#0 ← #1, copy imm #2 registers` |
+
+## Control flow
+
+### Unconditional jump
+- Type BD
+
+| Opcode | Name |        Action         |
+|:------:|:----:|:---------------------:|
+|   32   | JMP  | Jump at `#0 + imm #1` |
+
+### Conditional jumps
+- Type BBD
+- Jump at `imm #2` if `#0 <op> #1`
+
+| Opcode | Name |  Comparsion  |
+|:------:|:----:|:------------:|
+|   33   | JEQ  |      =       |
+|   34   | JNE  |      ≠       |
+|   35   | JLT  |  < (signed)  |
+|   36   | JGT  |  > (signed)  |
+|   37   | JLTU | < (unsigned) |
+|   38   | JGTU | > (unsigned) |
+
+### Environment call
+- Type N
+
+| Opcode | Name  |                Action                 |
+|:------:|:-----:|:-------------------------------------:|
+|   39   | ECALL | Cause an trap to the host environment |
+
+## Floating point operations
+- Type BBB
+- `#0 ← #1 <op> #2`
+
+| Opcode | Name |     Action     |
+|:------:|:----:|:--------------:|
+|   40   | ADDF |    Addition    |
+|   41   | MULF | Multiplication |
+
+### Division-remainder
+- Type BBBB
+
+| Opcode | Name |                 Action                 |
+|:------:|:----:|:--------------------------------------:|
+|   42   | DIRF | Same flow applies as for integer `DIR` |
+
+## Floating point immediate operations
+- Type BBD
+- `#0 ← #1 <op> imm #2`
+
+| Opcode | Name  |     Action     |
+|:------:|:-----:|:--------------:|
+|   43   | ADDFI |    Addition    |
+|   44   | MULFI | Multiplication |
+
+# Registers
+- There is 255 registers + one zero register (with index 0)
+- Reading from zero register yields zero
+- Writing to zero register is a no-op
+
+# Memory
+- Addresses are 64 bit
+- Memory implementation is arbitrary
+- In case of accessing invalid address:
+    - Program shall trap (LoadAccessEx, StoreAccessEx) with parameter of accessed address
+    - Value of register when trapped is undefined
+
+## Recommendations
+- Leave address `0x0` as invalid
+- If paging used:
+    - Leave first page invalid
+    - Pages should be at least 4 KiB
+
+# Program execution
+- The way of program execution is implementation defined
+- The order of instruction is arbitrary, as long all observable
+    effects are applied in the program's order
+
+# Program validation
+- Invalid program should cause runtime error:
+    - The form of error is arbitrary. Can be a trap or an interpreter-specified error
+    - It shall not be handleable from within the program
+- Executing invalid opcode should trap
+- Program can be validaded either before execution or when executing
+
+# Traps
+Program should at least implement these traps:
+- Environment call
+- Invalid instruction exception
+- Load address exception
+- Store address exception
+
+and executing environment should be able to get information about them,
+like the opcode of invalid instruction or attempted address to load/store.
+Details about these are left as an implementation detail.
+
+# Assembly
+HoleyBytes assembly format is not defined, this is just a weak description
+of `hbasm` syntax.
+
+- Opcode names correspond to specified opcode names, lowercase (`nop`)
+- Parameters are separated by comma (`addi r0, r0, 1`)
+- Instructions are separated by either line feed or semicolon
+- Registers are represented by `r` followed by the number (`r10`)
+- Labels are defined by label name followed with colon (`loop:`)
+- Labels are references simply by their name (`print`)
+- Immediates are entered plainly. Negative numbers supported.