Hane/8086-coded
1
0
Fork 0
Code Issues Pull requests Projects Releases Packages Wiki Activity

First assigment done (w/o writing to file)

Browse source
This commit is contained in:
Hane 2026-01-23 20:25:14 +01:00
commit 53463a5c6d
8 changed files with 129 additions and 0 deletions
Download patch file Download diff file Expand all files Collapse all files

104
1-1/decoder.c Normal file
View file

@ -0,0 +1,104 @@
#include <stdint.h>
#include <stdio.h>
#include <limits.h>
enum DT_INSTRUCTIONS
{
MOV_RM_TF_R = 0b1000'10, //d w
MOV_I_T_RM = 0b1100'011, // w
MOV_I_T_R = 0b1011, // w reg
MOV_M_T_A = 0b1010'000, // w
MOV_A_T_M = 0b1010'001, // w
MOV_RM_T_SR = 0b1000'1110,
MOV_SR_T_RM = 0b1000'1100,
};
enum MOV_REGISTER_MODE
{
MEM_NO_DISP = 0b00,
MEM_8BIT_DISP = 0b01,
MEM_16BIT_DISP = 0b010,
REG_NO_DISP = 0b11
};
char REG_ENCODING_TXT[0b10000][3] = { "al", "cl", "dl", "bl", "ah", "ch", "dh", "bh",
"ax", "cx", "dx", "bx", "sp", "bp", "si", "di"};
enum REG_ENCODING
{
R_AL = 0b000,
R_CL = 0b001,
R_DL = 0b010,
R_BL = 0b011,
R_AH = 0b100,
R_CH = 0b101,
R_DH = 0b110,
R_BH = 0b111
};
enum WREG_ENCODING
{
WR_AX = 0b000,
WR_CX = 0b001,
WR_DX = 0b010,
WR_BX = 0b011,
WR_SP = 0b100,
WR_BP = 0b101,
WR_SI = 0b110,
WR_DI = 0b111
};
typedef struct
{
FILE *binary;
uint64_t size;
} binary_data;
void MOV_RM_TF_R_parse(uint8_t byte1, uint8_t byte2, uint8_t byte3, uint8_t byte4)
{
const uint8_t wide_mask = 0b0000'0001;
const uint8_t dest_mask = 0b0000'0010;
const uint8_t mod_mask = 0b1100'0000;
const uint8_t regm_mask = 0b0011'1000;
if ((byte2 & mod_mask) != mod_mask) return;
//Since we're only doing register mode/register to register, both reg and r/m are affected by the W bit
bool reg_is_dest = (byte1 & dest_mask);
//if D=1, dest is retrieved from the reg field in byte2 and src from r/m
uint8_t dest_value = (reg_is_dest) ? ((byte2 & regm_mask) >> 3) + ((byte1 & wide_mask) * 8) : (byte2 & (regm_mask >> 3)) + ((byte1 & wide_mask) * 8);
uint8_t src_value = (reg_is_dest) ? (byte2 & (regm_mask >> 3)) + ((byte1 & wide_mask) * 8) : ((byte2 & regm_mask) >> 3) + ((byte1 & wide_mask) * 8);
printf("%s, %s\n", REG_ENCODING_TXT[dest_value], REG_ENCODING_TXT[src_value]);
return;
}
int main(int argc, char** argv)
{
if (argc != 2) return -1;
if (CHAR_BIT != 8) return -2;
binary_data bin;
unsigned char byte[1];
bin.binary = fopen(argv[1], "rb");
fseek(bin.binary, 0, SEEK_END);
bin.size = ftell(bin.binary);
fseek(bin.binary, 0, SEEK_SET);
for (int bytes_read = 0; bytes_read < bin.size; bytes_read++)
{
fread(byte, sizeof(byte), 1, bin.binary);
uint8_t manip_inst = (uint8_t)byte[0];
uint8_t inst = (uint8_t)byte[0];
//For now we're just checking for RM_TF_R
manip_inst = (manip_inst >> 2);
if (manip_inst != MOV_RM_TF_R) break;
printf("%s ", "mov");
if (bytes_read >= bin.size) break;
fread(byte, sizeof(byte), 1, bin.binary);
bytes_read++;
uint8_t inst_byte2 = (uint8_t)byte[0];
MOV_RM_TF_R_parse(inst, inst_byte2, 0, 0);
}
return 0;
}