/* compare ints - a test utility */

#include <errno.h>
#include <getopt.h>
#include <inttypes.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>

/*  Declarations */

/* Globals */

/* Functions */
int get_data(FILE *f, int64_t *dd, int signed_flag, int bytes) {
  int res;
  int8_t d_8;
  int16_t d_16;
  uint8_t d_u8;
  uint16_t d_u16;
  // TODO Loop on reads until, but catch EOF!!
  if (signed_flag) {
    switch (bytes) {
      case 1:
        res = fread(&d_8, bytes, 1, f);
        *dd = d_8;
        break;
      case 2:
        res = fread(&d_16, bytes, 1, f);
        *dd = d_16;
        break;
      default:
        fprintf(stderr, "Error: unsupported size %d bytes\n", bytes);
        exit(1);
    }
  } else {  // unsigned
    switch (bytes) {
      case 1:
        res = fread(&d_u8, bytes, 1, f);
        *dd = d_u8;
        break;
      case 2:
        res = fread(&d_u16, bytes, 1, f);
        *dd = d_u16;
        break;
      default:
        fprintf(stderr, "Error: unsupported size %d bytes\n", bytes);
        exit(1);
    }
  }

  if (res != 1)
    return (0);
  else
    return (1);
}

/* Main */

int main(int argc, char *argv[]) {
  char usage[] =
      "Usage: %s [-b size_in_bytes] [-c] [-s] [-t tolerance] [-n "
      "numerrorstoexit] file1 file2\n";

  int bytes = 1;
  int count_errors = 0;
  int signed_flag = 0;
  int tol = 1;
  int numerrorstoexit = -1;

  int opt;
  while ((opt = getopt(argc, argv, "b:cst:n:")) != -1) {
    switch (opt) {
      case 'b':
        bytes = atoi(optarg);
        break;
      case 'c':
        count_errors = 1;
        break;
      case 's':
        signed_flag = 1;
        break;
      case 'n':
        numerrorstoexit = atoi(optarg);
        break;
      case 't':
        tol = atof(optarg);
        break;
      default:
        fprintf(stderr, usage, argv[0]);
        exit(1);
    }
  }

  if ((optind + 2) > argc) {
    fprintf(stderr, usage, argv[0]);
    exit(1);
  }
  char *fname1 = argv[optind++];
  char *fname2 = argv[optind++];

  FILE *f1 = fopen(fname1, "rb");
  if (f1 == NULL) {
    fprintf(stderr, "Error opening file1 \"%s\": ", fname1);
    perror(NULL);
    exit(1);
  }

  FILE *f2 = fopen(fname2, "rb");
  if (f2 == NULL) {
    fprintf(stderr, "Error opening file2 \"%s\": ", fname2);
    perror(NULL);
    exit(1);
  }

  // Convert inputs to SIGNED long values
  int64_t data1, data2;

  int count = 0;
  int errors = 0;
  int rms_sum = 0;

  while (get_data(f1, &data1, signed_flag, bytes)) {
    if (!get_data(f2, &data2, signed_flag, bytes)) {
      fprintf(stderr, "Error: file2 is shorter\n");
      exit(1);
    }
    uint64_t err = llabs(data1 - data2);
    if (err > tol) {
      errors++;
      printf("%d %" PRId64 " %" PRId64 "\n", count, data1, data2);
      if (numerrorstoexit != -1)
        if (errors > numerrorstoexit) {
          printf("reached errors: %d, bailing!", numerrorstoexit);
          exit(1);
        }
    }
    rms_sum += (err * err);
    count++;
  }
  if (get_data(f2, &data2, signed_flag, bytes)) {
    fprintf(stderr, "Error: file1 is shorter\n");
    exit(1);
  }

  if (count_errors)
    exit(errors);
  else {
    if (errors) {
      printf("Fail: %d errors\n", errors);
      printf("      rms error = %f\n", ((double)rms_sum / count));
      exit(1);
    } else
      printf("Pass\n");
    exit(0);
  }

}  // main

/* vi:set ts=4 et sts=4: */