/* Linearly search utlfile/padr/SELE-SAL-CONSTA.p20out1.20230415.tmp
 * for Daniel Osmar Maidana’s CUIT.  A microbenchmark; takes 102 ms on
 * my MicroPC to search 6.25 million records.  See also columncuits.c
 * and findcuit.c.
 */

#include <stdio.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/mman.h>
#include <fcntl.h>
#include <string.h>

enum { recsize = 52 };

int main(int argc, char **argv)
{
  if (argc != 2) {
    fprintf(stderr, "Usage: %s utlfile/padr/SELE-SAL-CONSTA.p20out1.20230415.tmp\n",
            argv[0]);
    return 1;
  }

  int fd = open(argv[1], O_RDONLY);
  if (fd < 0) {
    perror(argv[1]);
    return -1;
  }
  
  off_t size = lseek(fd, 0, SEEK_END);
  printf("%s is %ld bytes\n", argv[1], size);

  char *mem = mmap(NULL, size, PROT_READ, MAP_SHARED, fd, (off_t)0);
  if (mem == MAP_FAILED) {
    perror("mmap");
    return 1;
  }
  close(fd);

  char buf[recsize+1] = {0};
  /* for (int off = 0; off < size; off = off * 2 + recsize) { */
  /*   memcpy(buf, mem + off, recsize); */
  /*   printf("%12d %s", off, buf); */
  /* } */

  char key[] = "23304663359";
  for (int off = 0; off <= size - recsize; off += recsize) {
    if (0 == memcmp(key, mem + off, sizeof(key) - 1)) {
      memcpy(buf, mem + off, recsize);
      printf("%12d %s", off, buf);
    }
  }        

  return 0;
}