package/utils/rbextract/src/rle.c

   1 /*
   2  *  RLE decoding routine
   3  *
   4  *  Copyright (C) 2012 Gabor Juhos <juhosg@openwrt.org>
   5  *
   6  *  This program is free software; you can redistribute it and/or modify it
   7  *  under the terms of the GNU General Public License version 2 as published
   8  *  by the Free Software Foundation.
   9  */
  10
  11 #include <stdio.h>
  12 #include <stddef.h>
  13 #include <stdint.h>
  14 #include <stdbool.h>
  15 #include <sys/types.h>
  16
  17 #include "rle.h"
  18
  19 int rle_decode(const unsigned char *src, size_t srclen,
  20                unsigned char *dst, size_t dstlen,
  21                size_t *src_done, size_t *dst_done)
  22 {
  23         size_t srcpos, dstpos;
  24         int ret;
  25
  26         srcpos = 0;
  27         dstpos = 0;
  28         ret = 1;
  29
  30         /* sanity checks */
  31         if (!src || !srclen || !dst || !dstlen)
  32                 goto out;
  33
  34         while (1) {
  35                 signed char count;
  36
  37                 if (srcpos >= srclen)
  38                         break;
  39
  40                 count = (signed char) src[srcpos++];
  41                 if (count == 0) {
  42                         ret = 0;
  43                         break;
  44                 }
  45
  46                 if (count > 0) {
  47                         unsigned char c;
  48
  49                         if (srcpos >= srclen)
  50                                 break;
  51
  52                         c = src[srcpos++];
  53
  54                         while (count--) {
  55                                 if (dstpos >= dstlen)
  56                                         break;
  57
  58                                 dst[dstpos++] = c;
  59                         }
  60                 } else {
  61                         count *= -1;
  62
  63                         while (count--) {
  64                                 if (srcpos >= srclen)
  65                                         break;
  66                                 if (dstpos >= dstlen)
  67                                         break;
  68                                 dst[dstpos++] = src[srcpos++];
  69                         }
  70                 }
  71         }
  72
  73 out:
  74         if (src_done)
  75                 *src_done = srcpos;
  76         if (dst_done)
  77                 *dst_done = dstpos;
  78
  79         return ret;
  80 }