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done for now, doing validation suite next.

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ed
2026-09-09 17:01:22 -04:00
parent 7daa333a71
commit 2a89a342df
7 changed files with 147 additions and 230 deletions
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code/8086/decoder.c
+12 -21
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@@ -95,24 +95,23 @@ x8616_decode_opcode(X8616_DecodePlan const* plan, U1 header)
if (plan->flags & x8616_plan_has_sr) field_mask |= x8616_field_mask(plan->sr_shift, X8616_OPCODE_SR_WIDTH);
if (plan->flags & x8616_plan_has_alu) field_mask |= x8616_field_mask(plan->alu_shift, X8616_OPCODE_ALU_TTT_WIDTH);
if (plan->flags & x8616_plan_has_cc) field_mask |= x8616_field_mask(plan->cc_shift, X8616_OPCODE_CC_WIDTH);
if (plan->flags & x8616_plan_has_pair) field_mask |= x8616_field_mask(plan->pair_shift, X8616_OPCODE_PAIR_WIDTH);
if (field_mask == 0) return 0;
if (field_mask == 0) return C_(X8616_Opcode, header);
U1 opcode_mask = u1_(~field_mask);
if (opcode_mask == 0) return 0;
if (opcode_mask == 0) return C_(X8616_Opcode, header);
return C_(X8616_Opcode, (header & opcode_mask) >> count_trailing_zeros_u4(opcode_mask));
}
internal void
x8616_decode_apply_prefix(X8616_DecodePlex_R plex, X8616_DecodePlan_R plan, U1 opcode) {
x8616_decode_apply_prefix(X8616_DecodePlex_R plex, X8616_DecodePlan_R plan, U1 header) {
plex->prefixes.count += 1;
plex->prefixes.lock |= plan->prefix_kind == x8616_prefix_lock;
if (plan->prefix_kind == x8616_prefix_repeat) {
plex->prefixes.has_repeat = 1;
plex->prefixes.repeat = C_(X8616_Repeat, x8616_bit_field_extract(opcode, (X8616_BitField){ plan->z_shift, X8616_OPCODE_BIT_WIDTH }));
plex->prefixes.repeat = C_(X8616_Repeat, x8616_bit_field_extract(header, (X8616_BitField){ plan->z_shift, X8616_OPCODE_BIT_WIDTH }));
}
if (plan->prefix_kind == x8616_prefix_segment) {
plex->prefixes.has_segment = 1;
plex->prefixes.segment = C_(X8616_Segment, x8616_bit_field_extract(opcode, (X8616_BitField){ plan->sr_shift, X8616_OPCODE_SR_WIDTH }));
plex->prefixes.segment = C_(X8616_Segment, x8616_bit_field_extract(header, (X8616_BitField){ plan->sr_shift, X8616_OPCODE_SR_WIDTH }));
}
}
@@ -121,18 +120,18 @@ x8616_decode_one_plex(X8616_DecodePlex* plex)
{
U4 prefix_at = 0;
// Prefix pass. Ambiguous/group opcodes are never prefixes, so only direct
// dispatch entries participate in this loop.
// Prefix pass. LOCK / REP / segment are prior bytes. Encodings that need a
// second byte (aux dispatch) are never prefixes.
while (prefix_at < plex->source_size)
{
U1 prefix_opcode = plex->source[prefix_at];
U2 prefix_dispatch = x8616_decode_dispatch[prefix_opcode];
U1 prefix_header = plex->source[prefix_at];
U2 prefix_dispatch = x8616_decode_dispatch[prefix_header];
if (prefix_dispatch == false || (prefix_dispatch & X8616_DECODE_AUX_BIT)) break;
X8616_DecodePlan_R prefix_plan = x8616_decode_plans + prefix_dispatch;
if ((prefix_plan->flags & x8616_plan_is_prefix) == false) break;
x8616_decode_apply_prefix(plex, prefix_plan, prefix_opcode);
x8616_decode_apply_prefix(plex, prefix_plan, prefix_header);
++ prefix_at;
}
@@ -200,7 +199,7 @@ x8616_decode_one_plex(X8616_DecodePlex* plex)
plex->plan = x8616_decode_plans + plex->plan_idx;
// A direct-dispatch plan may still have a constrained second byte.
// Group opcodes with multiple candidates were already resolved through aux.
// Headers with multiple catalog rows were already resolved through aux.
if (plex->plan_idx && (plex->plan->flags & (x8616_plan_has_modrm | x8616_plan_has_post_opcode)))
{
if (body_source_size < 2)
@@ -439,15 +438,7 @@ x8616_decode_one_plex(X8616_DecodePlex* plex)
plex->instruction.alu = plex->alu;
plex->instruction.op = x8616_op_from_alu[digit];
}
else if (plan->digit_kind == x8616_digit_shift) plex->instruction.op = x8616_op_from_shift[digit];
else if (plan->digit_kind == x8616_digit_g3) plex->instruction.op = x8616_op_from_g3[digit];
else if (plan->digit_kind == x8616_digit_ff) plex->instruction.op = x8616_op_from_ff[digit];
else if (plan->digit_kind == x8616_digit_incdec) plex->instruction.op = x8616_op_from_incdec[digit];
}
if (plan->flags & x8616_plan_has_pair) {
U1 bit = x8616_bit_field_extract(plex->header, (X8616_BitField){ plan->pair_shift, X8616_OPCODE_PAIR_WIDTH });
if (plan->pair_kind == x8616_pair_incdec) plex->instruction.op = x8616_op_from_incdec[bit];
if (plan->pair_kind == x8616_pair_pushpop) plex->instruction.op = x8616_op_from_pushpop[bit];
else if (plan->digit_kind == x8616_digit_shift) plex->instruction.op = x8616_op_from_shift[digit];
}
plex->instruction.flags = plan->encoding_flags;
plex->instruction.decode_flags = (plex->encoding_invalid ? x8616_decode_invalid : 0) | (plex->classification_truncated ? x8616_decode_truncated : 0);