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Changes to preprocessor functions (#17)
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* Removed redundant pre processor functions

Some pre-processor function calls for instruction encoder identities
such as `ZO`. Previously the `pre_default()` pre processor function
was called to check if the operand sizes are the same; However in
this special edge case where there are *no* operands, we can simply
ignore this behaviour.

* Renamed `pre_default`

The previous name of `pre_default` seemed *too general* and infered
that this is the default behavior of the assembler, however desc-
ribing the pre processor function as `same_operand_sizes` more ac-
curatly encapsulates the expected behavior instead of needing to
skim over the code before adding it.

* Broken the line for `syscall` for code readability
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@cheng-alvin
cheng-alvin authored Dec 21, 2024
1 parent 9f60a20 commit 51ae5fc
Showing 1 changed file with 23 additions and 20 deletions.
43 changes: 23 additions & 20 deletions libjas/instruction.c
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Original file line number Diff line number Diff line change
Expand Up @@ -27,7 +27,7 @@
#include "error.h"
#include <stddef.h>

static void pre_default(operand_t *op_arr, buffer_t *buf, instr_encode_table_t *instr_ref, enum modes mode) {
static void same_operand_sizes(operand_t *op_arr, buffer_t *buf, instr_encode_table_t *instr_ref, enum modes mode) {
const uint8_t ref = op_sizeof(op_arr[0].type);

for (uint8_t i = 0; i < 4; i++) {
Expand All @@ -42,15 +42,15 @@ static void pre_default(operand_t *op_arr, buffer_t *buf, instr_encode_table_t *

static void pre_imm(operand_t *op_arr, buffer_t *buf, instr_encode_table_t *instr_ref, enum modes mode) {
if (op_sizeof(op_arr[0].type) != 64) {
pre_default(op_arr, buf, instr_ref, mode);
same_operand_sizes(op_arr, buf, instr_ref, mode);
return;
}
}

static instr_encode_table_t mov[] = {
{OP_MR, NULL, {0x89}, MODE_SUPPORT_ALL, {0x88}, 1, &pre_default},
{OP_RM, NULL, {0x8B}, MODE_SUPPORT_ALL, {0x8A}, 1, &pre_default},
{OP_OI, NULL, {0xB8}, MODE_SUPPORT_ALL, {0xB0}, 1, &pre_default},
{OP_MR, NULL, {0x89}, MODE_SUPPORT_ALL, {0x88}, 1, &same_operand_sizes},
{OP_RM, NULL, {0x8B}, MODE_SUPPORT_ALL, {0x8A}, 1, &same_operand_sizes},
{OP_OI, NULL, {0xB8}, MODE_SUPPORT_ALL, {0xB0}, 1, &same_operand_sizes},
{OP_MI, 0b10000000, {0xC7}, MODE_SUPPORT_ALL, {0xC6}, 1, &pre_imm},

INSTR_TERMINATOR,
Expand All @@ -67,8 +67,8 @@ static void pre_lea(operand_t *op_arr, buffer_t *buf, instr_encode_table_t *inst
// clang-format off

#define INSTR_GENERAL(rm, rm_byte, mr, mr_byte,i, i_byte, mi_ext, mi, mi_byte) \
{OP_MR, NULL, {mr}, MODE_SUPPORT_ALL, {mr_byte}, 1, &pre_default}, \
{OP_RM, NULL, {rm}, MODE_SUPPORT_ALL, {rm_byte}, 1, &pre_default}, \
{OP_MR, NULL, {mr}, MODE_SUPPORT_ALL, {mr_byte}, 1, &same_operand_sizes}, \
{OP_RM, NULL, {rm}, MODE_SUPPORT_ALL, {rm_byte}, 1, &same_operand_sizes}, \
{OP_MI, mi_ext, {mi}, MODE_SUPPORT_ALL, {mi_byte}, 1, &pre_imm}, \
{OP_I, NULL, {i}, MODE_SUPPORT_ALL, {i_byte}, 1, &pre_imm}, \
INSTR_TERMINATOR,
Expand All @@ -79,8 +79,8 @@ static instr_encode_table_t lea[] = {{OP_RM, NULL, {0x8D}, MODE_SUPPORT_ALL, {0x

static instr_encode_table_t add[] = {INSTR_GENERAL(0x03, 0x02, 0x01, 0x00, 0x03, 0x02, 0b10000000, 0x81, 0x80)};
static instr_encode_table_t sub[] = {INSTR_GENERAL(0x2B, 0x2A, 0x28, 0x29, 0x2C, 0x2D, 5, 0x81, 0x80)};
static instr_encode_table_t mul[] = {{OP_M, 4, {0xF7}, MODE_SUPPORT_ALL, {0xF6}, 1, &pre_default}, INSTR_TERMINATOR};
static instr_encode_table_t div[] = {{OP_M, 6, {0xF7}, MODE_SUPPORT_ALL, {0xF6}, 1, &pre_default}, INSTR_TERMINATOR};
static instr_encode_table_t mul[] = {{OP_M, 4, {0xF7}, MODE_SUPPORT_ALL, {0xF6}, 1, &same_operand_sizes}, INSTR_TERMINATOR};
static instr_encode_table_t div[] = {{OP_M, 6, {0xF7}, MODE_SUPPORT_ALL, {0xF6}, 1, &same_operand_sizes}, INSTR_TERMINATOR};

// Note all or, and and xor instructions have a imm8 which is not supported

Expand All @@ -90,10 +90,10 @@ static instr_encode_table_t xor [] = {INSTR_GENERAL(0x33, 0x32, 0x31, 0x30, 0x35

// ---

static instr_encode_table_t _not[] = {{OP_M, 2, {0xF7}, MODE_SUPPORT_ALL, {0xF6}, 1, &pre_default}, INSTR_TERMINATOR};
static instr_encode_table_t _not[] = {{OP_M, 2, {0xF7}, MODE_SUPPORT_ALL, {0xF6}, 1, &same_operand_sizes}, INSTR_TERMINATOR};

static instr_encode_table_t inc[] = {{OP_M, 0, {0xFF}, MODE_SUPPORT_ALL, {0xFE}, 1, &pre_default}, INSTR_TERMINATOR};
static instr_encode_table_t dec[] = {{OP_M, 1, {0xFF}, MODE_SUPPORT_ALL, {0xFE}, 1, &pre_default}, INSTR_TERMINATOR};
static instr_encode_table_t inc[] = {{OP_M, 0, {0xFF}, MODE_SUPPORT_ALL, {0xFE}, 1, &same_operand_sizes}, INSTR_TERMINATOR};
static instr_encode_table_t dec[] = {{OP_M, 1, {0xFF}, MODE_SUPPORT_ALL, {0xFE}, 1, &same_operand_sizes}, INSTR_TERMINATOR};

static void pre_jcc_no_byte(operand_t *op_arr, buffer_t *buf, instr_encode_table_t *instr_ref, enum modes mode) {
if (op_sizeof(op_arr[0].type) == 8)
Expand Down Expand Up @@ -124,7 +124,7 @@ static void pre_ret(operand_t *op_arr, buffer_t *buf, instr_encode_table_t *inst

// TODO / note far jumps, calls and returns are not supported (yet)
static instr_encode_table_t ret[] = {
{OP_ZO, NULL, {0xC3}, MODE_SUPPORT_ALL, {0xC3}, 1, &pre_default},
{OP_ZO, NULL, {0xC3}, MODE_SUPPORT_ALL, {0xC3}, 1, NULL},
{OP_I, NULL, {0xC2}, MODE_SUPPORT_ALL, {0xC2}, 1, &pre_ret},
INSTR_TERMINATOR,
};
Expand All @@ -147,21 +147,24 @@ static instr_encode_table_t pop[] = {
static instr_encode_table_t in[] = {{}};
static instr_encode_table_t out[] = {{}};

static instr_encode_table_t clc[] = {{OP_ZO, NULL, {0xF8}, MODE_SUPPORT_ALL, {0xF8}, 1, &pre_default}, INSTR_TERMINATOR};
static instr_encode_table_t stc[] = {{OP_ZO, NULL, {0xF9}, MODE_SUPPORT_ALL, {0xF9}, 1, &pre_default}, INSTR_TERMINATOR};
static instr_encode_table_t cli[] = {{OP_ZO, NULL, {0xFA}, MODE_SUPPORT_ALL, {0xFA}, 1, &pre_default}, INSTR_TERMINATOR};
static instr_encode_table_t sti[] = {{OP_ZO, NULL, {0xFB}, MODE_SUPPORT_ALL, {0xFB}, 1, &pre_default}, INSTR_TERMINATOR};
static instr_encode_table_t clc[] = {{OP_ZO, NULL, {0xF8}, MODE_SUPPORT_ALL, {0xF8}, 1, NULL}, INSTR_TERMINATOR};
static instr_encode_table_t stc[] = {{OP_ZO, NULL, {0xF9}, MODE_SUPPORT_ALL, {0xF9}, 1, NULL}, INSTR_TERMINATOR};
static instr_encode_table_t cli[] = {{OP_ZO, NULL, {0xFA}, MODE_SUPPORT_ALL, {0xFA}, 1, NULL}, INSTR_TERMINATOR};
static instr_encode_table_t sti[] = {{OP_ZO, NULL, {0xFB}, MODE_SUPPORT_ALL, {0xFB}, 1, NULL}, INSTR_TERMINATOR};

static instr_encode_table_t nop[] = {{OP_ZO, NULL, {0x90}, MODE_SUPPORT_ALL, {0x90}, 1, &pre_default}, INSTR_TERMINATOR};
static instr_encode_table_t hlt[] = {{OP_ZO, NULL, {0xF4}, MODE_SUPPORT_ALL, {0xF4}, 1, &pre_default}, INSTR_TERMINATOR};
static instr_encode_table_t nop[] = {{OP_ZO, NULL, {0x90}, MODE_SUPPORT_ALL, {0x90}, 1, NULL}, INSTR_TERMINATOR};
static instr_encode_table_t hlt[] = {{OP_ZO, NULL, {0xF4}, MODE_SUPPORT_ALL, {0xF4}, 1, NULL}, INSTR_TERMINATOR};

static void pre_int(operand_t *op_arr, buffer_t *buf, instr_encode_table_t *instr_ref, enum modes mode) {
if (op_sizeof(op_arr[0].type) != 8)
err("Invalid operand size for INT instruction.");
}

static instr_encode_table_t _int[] = {{OP_I, NULL, {0xCD}, MODE_SUPPORT_ALL, {0xCD}, 1, &pre_int}, INSTR_TERMINATOR};
static instr_encode_table_t syscall[] = {{OP_ZO, NULL, {0x0F, 0x05}, MODE_SUPPORT_64BIT, {0x00, 0x00}, 2, &pre_default}, INSTR_TERMINATOR};
static instr_encode_table_t syscall[] = {
{OP_ZO, NULL, {0x0F, 0x05}, MODE_SUPPORT_64BIT, {0x00, 0x00}, 2, &same_operand_sizes},
INSTR_TERMINATOR,
};

// clang-format off

Expand Down

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