disasm.c

#include <stdio.h>
#include <stdint.h>

typedef uint32_t uint;

uint
read_ins()
{
  uint u = 0;

  u = (u << 8) + (uint)getchar();
  u = (u << 8) + (uint)getchar();
  u = (u << 8) + (uint)getchar();
  u = (u << 8) + (uint)getchar();

  return u;
}

#define SLICE(u, i, j) \
  (((u) << (31 - i)) >> ((31 - i) + j))

char reg[32][4];
char *alu_op[] = {
  [0] = "add",
  [1] = "sub",
  [2] = "shl",
  [3] = "shr",
  [4] = "sar",
  [5] = "and",
  [6] = "or",
  [7] = "xor",
  [24] = "cmpne",
  [25] = "cmpeq",
  [26] = "cmplt",
  [27] = "cmple",
  [28] = "fcmpne",
  [29] = "fcmpeq",
  [30] = "fcmplt",
  [31] = "fcmple",
};
char *fpu_op[] = {
  [0] = "fadd",
  [1] = "fsub",
  [2] = "fmul",
  [3] = "fdiv",
  [4] = "finv",
  [5] = "fsqrt",
  [6] = "ftoi",
  [7] = "itof",
  [8] = "floor",
};
char *fpu_sig[] = {
  [0] = "",
  [1] = ".neg",
  [2] = ".abs",
  [3] = ".abs.neg",
};
char *misc_op[] = {
  [2] = "ldl",
  [3] = "ldh",
  [4] = "sysenter",
  [5] = "sysexit",
  [6] = "st",
  [8] = "ld",
  [11] = "jl",
  [12] = "jr",
  [13] = "bne",
  [15] = "beq"
};
char *misc_pre[] = {
  [0] = "-",
  [3] = "+"
};

void
print_ins_i(uint rx, uint ra, uint rb, uint lit, uint tag)
{
  printf("%s %s, %s, %s, %d\n", alu_op[tag], reg[rx], reg[ra], reg[rb], lit);
}

void
print_ins_f(uint rx, uint ra, uint rb, uint sig, uint tag)
{
  printf("%s%s %s, %s, %s\n", fpu_op[tag], fpu_sig[sig], reg[rx], reg[ra], reg[rb]);
}

void
print_ins_m(uint op, uint rx, uint ra, uint pre, uint disp)
{
  printf("%s%s %s, %s, %d\n", misc_op[op], misc_pre[pre], reg[rx], reg[ra], disp);
}

void
print_ins(uint ins)
{
  uint op, rx, ra, rb, lit, tag, sig, pre, disp;

  op = SLICE(ins, 31, 28);
  rx = SLICE(ins, 27, 23);
  ra = SLICE(ins, 22, 18);
  rb = SLICE(ins, 17, 13);
  lit = SLICE(ins, 12, 5);
  tag = SLICE(ins, 4, 0);
  sig = SLICE(ins, 6, 5);
  pre = SLICE(ins, 17, 16);
  disp = SLICE(ins, 15, 0);

  switch (op) {
  case 0x0:
    print_ins_i(rx, ra, rb, lit, tag);
    break;
  case 0x1:
    print_ins_f(rx, ra, rb, sig, tag);
    break;
  default:
    print_ins_m(op, rx, ra, pre, disp);
    break;
  }
}

int
main(int argc, char *argv[])
{
  int i;
  uint32_t u;

  if (! freopen(argv[1], "r", stdin)) {
    fprintf(stderr, "cannot open file %s\n", argv[1]);
    return 1;
  }

  for (i = 0; i < 32; ++i) {
    sprintf(reg[i], "r%d", i);
  }

  do {
    u = read_ins();
    print_ins(u);
    fflush(stdout);
  } while (! feof(stdin));

  return 0;
}