#include "insn.h"
#include "cpu.h"
#include "util.h"

#include <stddef.h>

#define TABLE_SIZE 0x34

static cpu_insn_handler primary_insn_handler[TABLE_SIZE] = {NULL};
static cpu_insn_handler secondary_insn_handler[TABLE_SIZE] = {NULL};

static inline op_primary_t extract_primary_op(uint32_t insn) {
  return (insn >> 26) & 0x3f;
}

static inline op_secondary_t extract_secondary_op(uint32_t insn) {
  return (insn >> 0) & 0x3f;
}

void insn_execute(cpu_t *cpu, uint32_t raw_insn) {
  const op_primary_t op = extract_primary_op(raw_insn);
  const insn_t insn = *(insn_t *)&raw_insn;

  if (op == SPECIAL) {
    const op_secondary_t op2 = extract_secondary_op(raw_insn);

    if (op2 > TABLE_SIZE || secondary_insn_handler[op2] == NULL) {
      fatal("unsupported instruction: insn=%08x, op=%02x, op2=%02x", raw_insn,
            op, op2);
    }

    secondary_insn_handler[op2](cpu, insn);
  }

  if (op > TABLE_SIZE || primary_insn_handler[op] == NULL) {
    fatal("unsupported instruction: insn=%08x, op=%02x", raw_insn, op);
  }

  primary_insn_handler[op](cpu, insn);
}