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#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <string.h>
typedef struct field field;
struct field {
const char *byte_name;
const char *word_name;
unsigned short bits[3];
};
const int FIELDS_COUNT = 8;
field fields[FIELDS_COUNT] {
{"ax", "al", {0, 0, 0}},
{"si", "cl", {0, 0, 1}},
{"dx", "dl", {0, 1, 0}},
{"bx", "bl", {0, 1, 1}},
{"sp", "ah", {1, 0, 0}},
{"bp", "ch", {1, 0, 1}},
{"si", "dh", {1, 1, 0}},
{"di", "bh", {1, 1, 1}},
};
const char *get_field(unsigned short bits[3], unsigned short w) {
for(int index = 0; index < FIELDS_COUNT; ++index) {
if(!w) { if(memcmp(bits, fields[index].bits, 3) == 0) { return fields[index].byte_name;} }
else { if(memcmp(bits, fields[index].bits, 3) == 0) { return fields[index].word_name;} }
}
}
typedef struct inst inst;
struct inst {
const char *instruction;
unsigned short bits[8];
};
const int INST_COUNT = 3;
const inst instructions[INST_COUNT] {
{"mov", {1, 0, 0, 0, 1, 0}},
{"add", {}},
{"sub", {}},
};
int main(int argc, char **argv) {
if(argc <= 1) { return 1;}
struct stat sb;
if (lstat(argv[1], &sb) == -1) {
perror("lstat");
exit(EXIT_FAILURE);
}
size_t size = sb.st_size;
char *buffer = (char *)malloc(size);
int fd = open(argv[1], O_RDONLY);
size_t read_count = read(fd, buffer, size);
if(read_count != size) {
printf("i think this is an error");
return 1;
}
for(int index = 0; index != size; ++index) {
char *line = (char *)malloc(8);
unsigned char byte = (unsigned char)buffer[index];
for(int pos = 7; pos >= 0; --pos) {
line[pos] = (byte >> pos) & 1 ? '1' : '0';
}
// check for mov instruction
{
bool result = true;
for(int regular = 0, reverse = 5; regular < 5, reverse >= 0; ++regular, --reverse) {
if(line[reverse] - '0' != instructions[0].bits[regular]) { result = false; }
}
if(result) { printf("mov\n");}
}
// check for second 8 bits
{
bool result = true;
int field_index = 0;
for(int field_idx = 0; field_idx < FIELDS_COUNT; ++field_idx) {
unsigned short d = 0;
unsigned short w = 0;
for(int regular = 0, reverse = 5; regular < 5, reverse >= 0; ++regular, --reverse) {
if(line[reverse] - '0' != fields[field_idx].bits[regular]) {
result = false;
}
}
if(result) { printf(" %s,", get_field(fields[field_idx], 2)); }
}
}
free(line);
}
free(buffer);
close(fd);
return 0;
}
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