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#include <stdio.h>
typedef enum {
A = 0,
B,
} Registers;
typedef enum {
FLAG_ZERO = 1,
FLAG_NEGATIVE = 1 << 1,
} Flags;
typedef enum {
OP_ADD,
OP_ADD_VALUE,
OP_HALT,
OP_JMP_REL,
OP_LOAD,
OP_NOP,
OP_PRINT,
} OpCode;
static void
set_flags(int value, int *flags_register)
{
if (value == 0)
*flags_register |= FLAG_ZERO;
if (value < 0)
*flags_register |= FLAG_NEGATIVE;
}
int main() {
int program[] = {
OP_LOAD, A, 3,
OP_LOAD, B, 5,
OP_ADD, B,
OP_PRINT, A,
OP_LOAD, B, 1,
OP_ADD, B,
OP_PRINT, A,
/*
OP_ADD_VALUE, 2,
OP_NOP,
OP_JMP_REL, -5,
*/
OP_HALT
};
int registers[2] = { 0 };
int flags_register = 0;
int *ip = program;
while (1) {
OpCode op = *ip++;
switch (op) {
case OP_LOAD: {
int idx = *ip++;
registers[idx] = *ip++;
set_flags(registers[idx], &flags_register);
break;
}
case OP_ADD: {
int val = registers[*ip++];
registers[A] += val;
set_flags(registers[A], &flags_register);
break;
}
case OP_ADD_VALUE: {
/* TODO */
break;
}
case OP_JMP_REL: {
/* TODO */
break;
}
case OP_NOP: {
/* TODO */
break;
}
case OP_PRINT:
printf("%d\n", registers[*ip++]);
break;
case OP_HALT:
return 0;
default:
fprintf(stderr, "Unknown instruction %d\n", *ip);
return -1;
}
}
return 0;
}