imgsplit.c

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#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>

void
usage (void)
{
    fprintf (stderr, "usage: imgsplit\n");
    exit (1);
}

int
PCX_D (char *src,char *dest,unsigned src_size)
{
  char num;
  char *orig_dest = dest;
  do {
    if ((*src&0xc0)==0xc0) {
      num=*(src++)&0x3f; src_size--;
      while ((num--)>0) {*(dest++)=*src;}
      src++;src_size--;
    } else {
      (*dest++)=*(src++);src_size--;
    };
  }  while(src_size);
  return (dest - orig_dest);
}

int
read_img_frame (FILE *inf, char *rgb)
{
    unsigned char map[256 * 3];
    unsigned int len;
    char compressed[64 * 1024];
    int idx;
    unsigned char *up;
    char ipix[320 * 200];

    len = fread (&map, 1, sizeof map, inf);

    if (len == 0)
        return (-1);

    if (len != sizeof map)
        goto bad;
    
    if (fread (&len, 4, 1, inf) != 1)
        goto bad;

    if (len > sizeof compressed) {
        fprintf (stderr, "frame too big\n");
        goto bad;
    }

    if (fread (compressed, 1, len, inf) != len)
        goto bad;
        
    PCX_D (compressed, ipix, len);

    for (idx = 0; idx < 320 * 200; idx++) {
        up = map + (ipix[idx] & 0xff) * 3;
        *rgb++ = *up++ * 4;
        *rgb++ = *up++ * 4;
        *rgb++ = *up++ * 4;
    }

    return (0);

bad:
    fprintf (stderr, "bad img file\n");
    exit (1);
}

int
main (int argc, char **argv)
{
    int c;
    char *inname;
    FILE *inf;
    int fnum;
    char rgb[320 * 200 * 3];
    char outname[1000];
    FILE *outf;

    while ((c = getopt (argc, argv, "")) != EOF) {
        switch (c) {
        default:
            usage ();
        }
    }

    if (optind >= argc)
        usage ();

    inname = argv[optind++];

    if (optind != argc)
        usage ();

    if ((inf = fopen (inname, "rb")) == NULL) {
        fprintf (stderr, "can't open %s\n", inname);
        exit (1);
    }

    fnum = 0;

    while (1) {
        fnum++;

        if (read_img_frame (inf, rgb) < 0)
            break;
        
        sprintf (outname, "c%02d.ppm", fnum);
        if ((outf = fopen (outname, "wb")) == NULL) {
            fprintf (stderr, "can't create %s\n", outname);
            exit (1);
        }
        fprintf (outf, "P6\n320 200\n255\n");
        fwrite (rgb, 1, 3 * 320 * 200, outf);
        fclose (outf);
    }

    return (0);
}

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