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Instruction parser finished for MOV instructions with corner cases handled

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This commit is contained in:
Joseph Ferano 2024-01-16 21:44:03 +07:00
parent ca0742de3c
commit a0ed11416e
1 changed files with 112 additions and 56 deletions
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168
decode.c
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@ -34,7 +34,18 @@ typedef struct Register
u8 code; u8 code;
} Register; } Register;
enum OperandType {OPR_T_MEMORY, OPR_T_REGISTER, OPR_T_IMMEDIATE}; Register registers[8] = {
{.code = 0b000, .fullname = "ax", .bytename = "al"},
{.code = 0b001, .fullname = "cx", .bytename = "cl"},
{.code = 0b010, .fullname = "dx", .bytename = "dl"},
{.code = 0b011, .fullname = "bx", .bytename = "bl"},
{.code = 0b100, .fullname = "sp", .bytename = "ah"},
{.code = 0b101, .fullname = "bp", .bytename = "ch"},
{.code = 0b110, .fullname = "si", .bytename = "dh"},
{.code = 0b111, .fullname = "di", .bytename = "bh"},
};
enum OperandType {OPR_T_MEMORY, OPR_T_REGISTER, OPR_T_IMMEDIATE, OPR_T_DIRADDR};
typedef struct Operand typedef struct Operand
{ {
@ -53,19 +64,41 @@ typedef struct Operand
i16 value; i16 value;
u8 direct; u8 direct;
} imm; } imm;
struct DirAddr {
i16 value;
} dir_addr;
}; };
} Operand; } Operand;
Register registers[8] = { enum ParseRegType { P_REG_NONE, P_REG_MASK, P_REG_FIXED };
{.code = 0b000, .fullname = "ax", .bytename = "al"}, typedef struct ParseReg
{.code = 0b001, .fullname = "cx", .bytename = "cl"}, {
{.code = 0b010, .fullname = "dx", .bytename = "dl"}, enum ParseRegType tag;
{.code = 0b011, .fullname = "bx", .bytename = "bl"}, union {
{.code = 0b100, .fullname = "sp", .bytename = "ah"}, u8 none;
{.code = 0b101, .fullname = "bp", .bytename = "ch"}, u8 mask;
{.code = 0b110, .fullname = "si", .bytename = "dh"}, u8 fixed;
{.code = 0b111, .fullname = "di", .bytename = "bh"}, };
}; } ParseReg;
typedef struct InstFormat
{
u16 id;
char *name;
ParseReg parse_reg;
u8 inst_enc;
u8 mask_inst;
u8 mask_w;
bool has_operands;
bool has_displacement;
bool has_data;
bool has_d;
bool has_w;
bool has_mod;
bool has_rm;
bool has_s;
bool has_SR;
} InstFormat;
typedef struct ParsedInstruction typedef struct ParsedInstruction
{ {
@ -80,6 +113,7 @@ typedef struct ParsedInstruction
u8_opt reg; u8_opt reg;
u8_opt rm; u8_opt rm;
u8_opt SR; u8_opt SR;
u8 is_data_addr;
u8 bytes_read; u8 bytes_read;
} ParsedInstruction; } ParsedInstruction;
@ -92,8 +126,6 @@ typedef struct Instruction
u16 id; u16 id;
} Instruction; } Instruction;
char *memory[65536];
/// Get Effective Address Calculation Registers /// Get Effective Address Calculation Registers
char* get_eac_register(char rm) char* get_eac_register(char rm)
{ {
@ -137,45 +169,25 @@ static u8 mask_and_shift(u8 value, u8 mask)
return value; return value;
} }
typedef struct InstFormat
{
u16 id;
char *name;
u8 inst_enc;
u8 mask_inst;
u8 mask_w;
u8 mask_reg;
bool has_operands;
bool has_displacement;
bool has_data;
bool has_d;
bool has_w;
bool has_reg;
bool has_mod;
bool has_rm;
bool has_s;
bool has_SR;
} InstFormat;
InstFormat inst_formats[] = InstFormat inst_formats[] =
{ {
//////// ////////
// MOV // MOV
//////// ////////
// Register/memory to/from register // Register/memory to/from register
{.id=1, .name="mov", .inst_enc=0b10001000, .mask_inst=0x3, .mask_reg=0b00111000, {.id=1, .name="mov", .inst_enc=0b10001000, .mask_inst=0x3, .mask_w=0x1,
.mask_w=0x1, .has_operands=true, .has_displacement=true, .has_d=true, .has_w=true, .has_operands=true, .has_displacement=true, .has_d=true, .has_w=true,
.has_reg=true, .has_mod=true, .has_rm=true}, .has_mod=true, .has_rm=true, .parse_reg={.tag = P_REG_MASK, .mask=0b00111000} },
// Immediate to register/memory // Immediate to register/memory
{.id=2, .name="mov", .inst_enc=0b11000110, .mask_inst=0x1, .mask_w=0x1, .has_operands=true, {.id=2, .name="mov", .inst_enc=0b11000110, .mask_inst=0x1, .mask_w=0x1, .has_operands=true,
.has_displacement=true, .has_data=true, .has_w=true, .has_mod=true, .has_rm=true}, .has_displacement=true, .has_data=true, .has_w=true, .has_mod=true, .has_rm=true},
// Immediate to register // Immediate to register
{.id=3, .name="mov", .inst_enc=0b10110000, .mask_inst=0xF, .mask_w=0x8, {.id=3, .name="mov", .inst_enc=0b10110000, .mask_inst=0xF, .mask_w=0x8,
.mask_reg=0b00000111, .has_reg=true, .has_data=true, .has_w=true}, .parse_reg={.tag = P_REG_MASK, .mask=0b00000111}, .has_data=true, .has_w=true},
// Memory to accumulator | Accumulator to memory using the `d` bit // Memory to accumulator | Accumulator to memory using the `d` bit
// even though the manual doesn't specify it // even though the manual doesn't specify it
{.id=4, .name="mov", .inst_enc=0b10100000, .mask_inst=0x3, .mask_w=0x1, {.id=4, .name="mov", .inst_enc=0b10100000, .mask_inst=0x3, .mask_w=0x1, .has_data=true,
.has_data=true, .has_w=true, .has_d=true}, .has_w=true, .has_d=true, .parse_reg={.tag = P_REG_FIXED, .fixed=0x0}},
// Register/memory to segment register and inverse using the `d` bit // Register/memory to segment register and inverse using the `d` bit
{.id=5, .name="mov", .inst_enc=0b10001100, .mask_inst=0x3, .has_SR=true, .has_d=true, {.id=5, .name="mov", .inst_enc=0b10001100, .mask_inst=0x3, .has_SR=true, .has_d=true,
.has_displacement=true, .has_mod=true, .has_rm=true}, .has_displacement=true, .has_mod=true, .has_rm=true},
@ -183,14 +195,14 @@ InstFormat inst_formats[] =
// ADD // ADD
//////// ////////
// Reg/memory with register or either // Reg/memory with register or either
{.id=6, .name="add", .inst_enc=0b00000000, .mask_inst=0x3, .mask_w=0x1, {.id=6, .name="add", .inst_enc=0b00000000, .mask_inst=0x3, .has_displacement=true,
.has_operands=true, .has_displacement=true, .has_w=true, .mask_w=0x1, .has_operands=true, .has_w=true, .has_d=true, .has_mod=true,
.has_d=true, .has_reg=true, .has_mod=true, .has_rm=true}, .has_rm=true, .parse_reg={.tag = P_REG_MASK, .mask=0b00111000}},
// Immediate to register/memory // Immediate to register/memory
{.id=7, .name="add", .inst_enc=0b10000000, .mask_inst=0x3, .mask_w=0x1, .has_w=true, {.id=7, .name="add", .inst_enc=0b10000000, .mask_inst=0x3, .mask_w=0x1, .has_w=true,
.has_operands=true, .has_displacement=true, .has_data=true, .has_mod=true, .has_rm=true}, .has_operands=true, .has_displacement=true, .has_data=true, .has_mod=true, .has_rm=true},
{.id=8, .name="add", .inst_enc=0b00000100, .mask_inst=0x1, .mask_w=0x1, {.id=8, .name="add", .inst_enc=0b00000100, .mask_inst=0x1, .mask_w=0x1,
.has_data=true, .has_w=true}, .has_data=true, .has_w=true, .parse_reg={.tag = P_REG_FIXED, .fixed=0x0}},
}; };
ParsedInstruction parse_instruction(u8* buf) ParsedInstruction parse_instruction(u8* buf)
@ -218,6 +230,7 @@ ParsedInstruction parse_instruction(u8* buf)
u8_opt rm_opt = none_u8(); u8_opt rm_opt = none_u8();
u16_opt data_opt = none_u16(); u16_opt data_opt = none_u16();
u16_opt displacement_opt = none_u16(); u16_opt displacement_opt = none_u16();
u8 is_data_addr = false;
u16 bytes_read = 1; u16 bytes_read = 1;
bytes_read += fmt.has_operands ? 1 : 0; bytes_read += fmt.has_operands ? 1 : 0;
@ -227,10 +240,15 @@ ParsedInstruction parse_instruction(u8* buf)
if (fmt.has_rm) rm_opt = some_u8(buf[1] & 0x7); if (fmt.has_rm) rm_opt = some_u8(buf[1] & 0x7);
if (fmt.has_mod) mod_opt = some_u8((buf[1] & 0b11000000) >> 6); if (fmt.has_mod) mod_opt = some_u8((buf[1] & 0b11000000) >> 6);
if (fmt.has_w) w_opt = some_u8(mask_and_shift(buf[0], fmt.mask_w)); if (fmt.has_w) w_opt = some_u8(mask_and_shift(buf[0], fmt.mask_w));
if (fmt.has_reg) if (fmt.parse_reg.tag == P_REG_MASK)
{ {
u8 reg = fmt.has_operands ? buf[1] : buf[0]; u8 reg = fmt.has_operands ? buf[1] : buf[0];
reg_opt = some_u8(mask_and_shift(reg, fmt.mask_reg)); reg_opt = some_u8(mask_and_shift(reg, fmt.parse_reg.mask));
}
else if (fmt.parse_reg.tag == P_REG_FIXED)
{
reg_opt = some_u8(fmt.parse_reg.fixed);
is_data_addr = true;
} }
if (fmt.has_data) if (fmt.has_data)
{ {
@ -251,6 +269,11 @@ ParsedInstruction parse_instruction(u8* buf)
displacement_opt = some_u16(disp); displacement_opt = some_u16(disp);
bytes_read += mod_opt.value % 3; bytes_read += mod_opt.value % 3;
} }
else if (fmt.has_displacement && mod_opt.value == MODE_MEM_NO_DIS && rm_opt.value == 0x6)
{
displacement_opt = some_u16((i16)buf[3] << 8 | buf[2]);
bytes_read += 2;
}
return (ParsedInstruction) { return (ParsedInstruction) {
.id = fmt.id, .id = fmt.id,
@ -263,6 +286,7 @@ ParsedInstruction parse_instruction(u8* buf)
.mod = mod_opt, .mod = mod_opt,
.reg = reg_opt, .reg = reg_opt,
.rm = rm_opt, .rm = rm_opt,
.is_data_addr = is_data_addr,
.bytes_read = bytes_read, .bytes_read = bytes_read,
}; };
} }
@ -272,35 +296,55 @@ Instruction decode_instruction(ParsedInstruction inst)
Operand opr1 , opr2 = {0}; Operand opr1 , opr2 = {0};
i16 payload = 0; i16 payload = 0;
IF_LET_SOME(u16, data, inst.data) payload = data;
IF_LET_SOME(u8, mod, inst.mod) IF_LET_SOME(u8, mod, inst.mod)
{ {
opr1.tag = OPR_T_REGISTER; IF_LET_SOME(u8, reg, inst.reg)
opr1.reg.value = registers[(size_t)inst.reg.value]; {
opr1.reg.wide = inst.w.value; opr1.tag = OPR_T_REGISTER;
opr1.reg.value = registers[(size_t)reg];
opr1.reg.wide = inst.w.value;
}
else
{
opr1.tag = OPR_T_IMMEDIATE;
opr1.imm.value = inst.data.value;
// TODO: This is dumb, we shouldn't do it this way
opr1.imm.direct = inst.w.value + 1;
}
if (mod == MODE_RGSTR_MODE) if (mod == MODE_RGSTR_MODE)
{ {
opr2.tag = OPR_T_REGISTER; opr2.tag = OPR_T_REGISTER;
opr2.reg.value = registers[(size_t)inst.rm.value]; opr2.reg.value = registers[(size_t)inst.rm.value];
opr2.reg.wide = inst.w.value; opr2.reg.wide = inst.w.value;
} }
else if (mod == MODE_MEM_NO_DIS && inst.rm.value == 0x6)
{
opr2.tag = OPR_T_DIRADDR;
opr2.dir_addr.value = inst.displacement.value;
}
else else
{ {
opr2.tag = OPR_T_MEMORY; opr2.tag = OPR_T_MEMORY;
opr2.mem.eac_name = get_eac_register(inst.rm.value); opr2.mem.eac_name = get_eac_register(inst.rm.value);
opr2.mem.mode = mod; opr2.mem.mode = mod;
if (mod == MODE_MEM_DIS_08 || mod == MODE_MEM_DIS_16) opr2.mem.displacement = (i16)inst.displacement.value;
opr2.mem.displacement = (i16)inst.displacement.value;
} }
} }
else else
{ {
IF_LET_SOME(u16, data, inst.data) IF_LET_SOME(u16, data, inst.data)
{ {
opr1.tag = OPR_T_IMMEDIATE; if (inst.is_data_addr)
opr1.imm.value = (i16)data; {
// TODO: Have to fix this opr1.tag = OPR_T_DIRADDR;
opr1.imm.direct = 0; opr1.dir_addr.value = (i16)data;
}
else
{
opr1.tag = OPR_T_IMMEDIATE;
opr1.imm.value = (i16)data;
opr1.imm.direct = 0;
}
} }
IF_LET_SOME(u8, reg, inst.reg) IF_LET_SOME(u8, reg, inst.reg)
{ {
@ -345,6 +389,10 @@ void get_operand_string(char* str_buf, Operand oprnd)
size = oprnd.imm.direct == 1 ? "byte " : "word "; size = oprnd.imm.direct == 1 ? "byte " : "word ";
sprintf(str_buf, "%s%d", size, oprnd.imm.value); sprintf(str_buf, "%s%d", size, oprnd.imm.value);
} }
else if (oprnd.tag == OPR_T_DIRADDR)
{
sprintf(str_buf, "[%d]", oprnd.dir_addr.value);
}
} }
void get_instr_string(char* str_buf, Instruction inst) void get_instr_string(char* str_buf, Instruction inst)
@ -352,7 +400,7 @@ void get_instr_string(char* str_buf, Instruction inst)
char src_str[32], dst_str[32]; char src_str[32], dst_str[32];
get_operand_string(src_str, inst.src_opr); get_operand_string(src_str, inst.src_opr);
get_operand_string(dst_str, inst.dst_opr); get_operand_string(dst_str, inst.dst_opr);
sprintf(str_buf, "%s %s, %s ; Inst id->%d", inst.operation, dst_str, src_str, inst.id); sprintf(str_buf, "%s %s, %s", inst.operation, dst_str, src_str);
} }
bool mov_inst(FILE* f, unsigned char* buf, char inst) bool mov_inst(FILE* f, unsigned char* buf, char inst)
@ -508,6 +556,10 @@ bool add_inst(FILE* f, unsigned char* buf, char inst)
return bytes_read > 0; return bytes_read > 0;
} }
char *memory[65536];
// Keep this global for debugging purposes
u16 inst_count = 1;
int main(int argc, char** argv) int main(int argc, char** argv)
{ {
if (argc < 2) if (argc < 2)
@ -565,6 +617,10 @@ int main(int argc, char** argv)
bytes_processed += parsed.bytes_read; bytes_processed += parsed.bytes_read;
// printf("%s %d/%ld", inst_str_buf, bytes_processed, bytes_read); // printf("%s %d/%ld", inst_str_buf, bytes_processed, bytes_read);
printf("%s", inst_str_buf); printf("%s", inst_str_buf);
int len = strlen(inst_str_buf);
for (int i = 0; i < 32 - len; i++)
printf(" ");
printf("; %d, %d", inst_count++, inst.id);
} }
else else
{ {