From 1ded3630f43d24547a21c45464098b57852f6bf3 Mon Sep 17 00:00:00 2001
From: Igor M <m1el.2027@gmail.com>
Date: Mon, 18 Mar 2024 14:27:09 +0200
Subject: [PATCH] Add hello-name example, fix backslash offset

---
 examples/hello-name.S | 103 ++++++++++++++++++++++++++++++++++++++++++
 src/directive.c       |   3 +-
 2 files changed, 104 insertions(+), 2 deletions(-)
 create mode 100644 examples/hello-name.S

diff --git a/examples/hello-name.S b/examples/hello-name.S
new file mode 100644
index 0000000..992c559
--- /dev/null
+++ b/examples/hello-name.S
@@ -0,0 +1,103 @@
+jmp entry
+
+puts:
+; Write string to console
+;  r2: [IN] *const u8  String pointer
+;  r3: [IN] usize      String length
+
+    li8     r1, 0x1         ; Write syscall
+    brc     r2, r3, 2       ; Copy parameters
+    li8     r2, 0x1         ; STDOUT
+    eca
+
+    jal     r0, r31, 0
+
+gets:
+; Read string until end of buffer or LF
+;  r2: [IN] *mut u8    Buffer
+;  r3: [IN] usize      Buffer length
+
+    ; Register allocations:
+    ;  r33: *mut u8    Buffer end
+    ;  r34: u8         Immediate char
+    ;  r35: u8         Const [0x0A = LF]
+
+    li8     r35, 0x0A
+    add64   r33, r2, r3
+
+    ; Setup syscall
+    li8     r2, 0x1         ; Stdin
+    cp      r3, r2
+    li8     r4, 0x1         ; Read one char
+
+    jeq     r3, r33, end
+    loop:
+        li8     r1, 0x1     ; Read syscall
+        eca
+        addi64  r3, r3, 1
+        ld      r34, r3, 0, 1
+        jeq     r34, r35, end
+        jne     r3, r33, loop
+    
+    end:
+        ; Set copied amount
+        sub64   r1, r33, r3
+        addi64  r1, r1, -1
+        jal     r0, r31, 0
+
+alloc_pages:
+; Allocate pages
+;  r1: [OUT] *mut u8   Pointer to page
+;  r2: [IN]  u16       Page count
+
+    muli16  r3, r2, 4096    ; page count
+    li8     r1, 0x9         ; mmap syscall
+    li8     r2, 0x0         ; no address set, kernel chosen
+    li8     r4, 0x2         ; PROT_WRITE
+    li8     r5, 0x20        ; MAP_ANONYMOUS
+    li64    r6, -1          ; Doesn't map file
+    li8     r7, 0x0         ; Doesn't map file
+    eca
+
+    jal     r0, r31, 0
+
+entry:
+; Program entrypoint
+
+    ; Register allocations:
+    ; r32: *mut u8     Buffer
+    ; r36: usize       Read buffer length
+
+    ; Allocate one page (4096 KiB)
+    li8     r2, 1
+    jal     r31, r0, alloc_pages
+    cp      r32, r1
+
+    ; Print message
+    lra16   r2, r0, enter_your_name
+    li8     r3, 17
+    jal     r31, r0, puts
+
+    ; Read name
+    cp      r2, r32
+    li16    r3, 4096
+    jal     r31, r0, gets
+    cp      r36, r1
+
+    ; Print your name is
+    lra16   r2, r0, your_name_is
+    li8     r3, 15
+    jal     r31, r0, puts
+
+    ; And now print the name
+    cp      r2, r32
+    cp      r3, r36
+    jal     r31, r0, puts
+
+    tx
+
+
+enter_your_name:
+    .db "Enter your name: "
+your_name_is:
+    .db "\nYour name is: "
\ No newline at end of file
diff --git a/src/directive.c b/src/directive.c
index 913e40e..f6cd258 100644
--- a/src/directive.c
+++ b/src/directive.c
@@ -8,7 +8,6 @@ AsmError push_string(char *buf, char *input, size_t len) {
             }
             pos += 1;
             chr = input[pos];
-            size_t offset = 1;
             switch (chr) {
                 case '\\':
                     chr = '\\';
@@ -38,12 +37,12 @@ AsmError push_string(char *buf, char *input, size_t len) {
                     if (high > 15 || low > 15) {
                         return ErrStringBadHex;
                     }
+                    pos += 2;
                     chr = high << 4 | low;
                     break;
                 default:
                     return ErrBadStringEscape;
             }
-            pos += offset;
         }
         buf[ndata] = chr;
         ndata += 1;