disassembler.c

#include <assert.h>
#include <inttypes.h>
#include <stdio.h>
#include <string.h>

#include "rabbit_bif.h"
#include "rabbit_codewords.h"
#include "rabbit_io.h"

int main(int argc, char **argv) {
  if (argc != 2) {
    fprintf(stderr, "Need to pass file to execute.\n");
    return 1;
  }

  char *fn = argv[1];
  FILE *fp = fopen(fn, "r");
  if (fp == NULL) {
    fprintf(stderr, "Can't open `%s'.\n", fn);
    return 1;
  }

  while (1) {
    uint32_t word = 0;
    int nread = read_word(fp, &word);
    if (nread == 0) {
      fclose(fp);
      return 0;
    }
    printf("%.8x:\t", word);

    struct unpacked_s i = decode(word);
    assert(i.opcode < kNumInstrs);
    const char *name = instr_nargs[i.opcode].name;
    unsigned nargs = instr_nargs[i.opcode].nargs;

    uint32_t immediate = 0;
    printf("%s", name);
    if (i.opcode == Bif) {
      assert(i.rega < kNumBifs);
      printf(" %s\n", bif_names[i.rega]);
      continue;
    }

    if (nargs == 1 || nargs == 2 || nargs == 3) {
      putchar(' ');
      if (nargs == 2 || nargs == 3) {
        if (nargs == 3) {
          if (i.modes.rega_deref == 1) {
            printf("(r%d), ", i.rega);
          } else {
            printf("r%d, ", i.rega);
          }
        }

        if (i.modes.regb_deref == 1) {
          printf("(r%d), ", i.regb);
        } else {
          printf("r%d, ", i.regb);
        }
      }

      if (i.modes.regc_deref == 1) {
        putchar('(');
      }

      if (i.modes.immediate == 1) {
        nread = read_word(fp, &immediate);
        if (nread == 0) {
          return 1;
        }

        printf("$%d", immediate);
      } else {
        printf("r%d", i.regc);
      }

      if (i.modes.regc_deref) {
        putchar(')');
      }
    }
    putchar('\n');
  }
}