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Merge pull request #4 from m1el/int_comments_label_deref

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m1el 2024-03-11 13:22:55 +02:00 committed by GitHub
parent ce9ed30bac c56e675f2c
commit 642ba58eeb
1 changed files with 54 additions and 32 deletions
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86
src/hbas.c
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@ -110,16 +110,44 @@ size_t label_lookup(LabelVec *labels, char *name, size_t len) {
return INVALID;
}
// safety: assumes the buffer has enough place for specified integer size
// safety: assumes the buffer has enough place for specified integer size.
// `sign` is a bitset, where bit `1` indicates that value accepts a signed int,
// and bit `2` indicates that value accepts an unsigned int.
AsmError push_int_le(char *buf, uint64_t val, size_t size, uint8_t sign) {
int valid_uint = val >> (size * 8) == 0;
// Unsigned integers must have all upper bits set to zero. To check this,
// we shift the value right by the integer size and verify it equals zero.
int valid_uint = (val >> (size * 8)) == 0;
// For signed integers, the sign-extended high bits must match the sign bit.
// By shifting right by one less than the total bit size (size * 8 - 1),
// we isolate the sign bit and any sign-extended bits. For a value fitting
// in the signed range, this operation results in either 0 (for non-negative
// values) or -1 (for negative values due to sign extension).
int64_t int_shifted = ((int64_t)val) >> (size * 8 - 1);
int valid_int = int_shifted == 0 || (~int_shifted) == 0;
// Note: this assumes the format for `sign` is a bitset.
// To unify the check for both positive and negative cases, we adjust
// non-zero values (-1) by incrementing by 1. This turns -1 into 0,
// enabling a single check for 0 to validate both cases. This adjustment
// simplifies the validation logic, allowing us to use a single condition to
// check for proper sign extension or zero extension in the original value.
int_shifted += int_shifted != 0;
// A valid signed integer will have `int_shifted` equal to 0
// after adjustment, indicating proper sign extension.
int valid_int = int_shifted == 0;
// Validity bitmask to represents whether the value
// fits as signed, unsigned, or both.
int validity = valid_int | (valid_uint << 1);
// If the value's validity doesn't match the `sign` requirements,
// we report an overflow.
if ((validity & sign) == 0) {
return ErrImmediateOverflow;
}
// Write out the bytes of the integer to the buffer in little-endian order,
// starting with the lowest byte first.
for (size_t ii = 0; ii < size; ii += 1) {
buf[ii] = val & 0xff;
val >>= 8;
@ -128,7 +156,7 @@ AsmError push_int_le(char *buf, uint64_t val, size_t size, uint8_t sign) {
}
AsmError assemble_instr(InstHt ht, char *input, size_t len, Token *tok,
ByteVec *rv, HoleVec *holes, LabelVec *labels) {
ByteVec *rv, HoleVec *holes) {
const InstDesc *inst;
const char *type_str;
size_t nargs;
@ -168,7 +196,10 @@ AsmError assemble_instr(InstHt ht, char *input, size_t len, Token *tok,
*tok = token(input, len, tok->start + tok->len);
if (tok->kind == TokNeg) {
*tok = token(input, len, tok->start + tok->len);
is_negative = ~(uint64_t)0;
if (tok->kind != TokNumber) {
return ErrTriedNegateNonNumber;
}
is_negative -= 1;
}
if (chr == 'R') {
int reg = parse_register(&input[tok->start], tok->len);
@ -181,26 +212,18 @@ AsmError assemble_instr(InstHt ht, char *input, size_t len, Token *tok,
uint64_t num_to_write;
if (meta.rel == 1 || meta.size == 8) {
if (tok->kind == TokIdent) {
size_t idx = label_lookup(labels, &input[tok->start], tok->len);
if (idx == INVALID) {
if (ensure_push((ByteVec *)holes, 1, sizeof(Hole)) != 0) {
return ErrOutOfMemory;
}
holes->buf[holes->len] = (Hole){
.location = rv->len,
.origin = inst_start,
.str = &input[tok->start],
.len = tok->len,
.size = (size_t)meta.size,
};
holes->len += 1;
num_to_write = 0;
} else {
num_to_write = labels->buf[idx].location;
if (meta.size != 8) {
num_to_write -= inst_start;
}
if (ensure_push((ByteVec*)holes, sizeof(Hole), 1) != 0) {
return ErrOutOfMemory;
}
holes->buf[holes->len] = (Hole) {
.location = rv->len,
.origin = inst_start,
.str = &input[tok->start],
.len = tok->len,
.size = (size_t)meta.size,
};
holes->len += 1;
num_to_write = 0;
} else if (tok->kind == TokNumber) {
num_to_write = tok->num;
} else {
@ -221,18 +244,17 @@ AsmError assemble_instr(InstHt ht, char *input, size_t len, Token *tok,
}
AsmError err =
push_int_le(&rv->buf[rv->len], num_to_write, meta.size, meta.sign);
if (err != 0) {
if (err != ErrOk) {
return err;
}
rv->len += meta.size;
}
}
return 0;
return ErrOk;
}
AsmError assemble(InstHt ht, char *input, size_t len, ByteVec *out,
EInfo *einfo) {
AsmError assemble(InstHt ht, char *input, size_t len, ByteVec *out, EInfo *einfo) {
ByteVec rv = {malloc(MIN_SIZE), MIN_SIZE, 0};
HoleVec holes = {malloc(MIN_SIZE * sizeof(Hole)), MIN_SIZE, 0};
LabelVec labels = {malloc(MIN_SIZE * sizeof(Label)), MIN_SIZE, 0};
@ -312,7 +334,7 @@ AsmError assemble(InstHt ht, char *input, size_t len, ByteVec *out,
goto end;
}
line_state = 2;
err = assemble_instr(ht, input, len, &tok, &rv, &holes, &labels);
err = assemble_instr(ht, input, len, &tok, &rv, &holes);
pos = tok.start + tok.len;
if (err != 0) {
goto end;
@ -328,9 +350,9 @@ AsmError assemble(InstHt ht, char *input, size_t len, ByteVec *out,
Hole *hole = &holes.buf[ii];
size_t idx = label_lookup(&labels, hole->str, hole->len);
uint64_t num_to_write = labels.buf[idx].location;
uint8_t sign = 1;
uint8_t sign = 2;
if (hole->size != 8) {
sign = 2;
sign = 1;
num_to_write -= hole->origin;
}
err = push_int_le(&rv.buf[hole->location], num_to_write, hole->size, sign);