1 /* 2 * Copyright (C) 2001, 2002, and 2003 Roy Keene 3 * 4 * This program is free software; you can redistribute it and/or 5 * modify it under the terms of the GNU General Public License 6 * as published by the Free Software Foundation; either version 2 7 * of the License, or (at your option) any later version. 8 * 9 * This program is distributed in the hope that it will be useful, 10 * but WITHOUT ANY WARRANTY; without even the implied warranty of 11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 12 * GNU General Public License for more details. 13 * 14 * You should have received a copy of the GNU General Public License 15 * along with this program; if not, write to the Free Software 16 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. 17 * 18 * email: dact@rkeene.org 19 */ 20 21 22 #include "dact.h" 23 #include "comp_textrle.h" 24 #include <stdio.h> 25 #ifdef HAVE_UNISTD_H 26 #include <unistd.h> 27 #endif 28 #ifdef HAVE_STDLIB_H 29 #include <stdlib.h> 30 #endif 31 32 33 /* 34 mode - DACT_MODE_COMPR or DACT_MODE_DECMP 35 Determine whether to compress or decompress. 36 prev_block - Previous (uncompressed) block. 37 curr_block - The data to be compressed. 38 out_block - Where to put data after compression. 39 blk_size - Size of prev_block and curr_block. 40 */ 41 42 #if defined(AS_MODULE) && defined(USE_MODULES) 43 #include "module.h" 44 uint32_t DC_NUM=12; 45 uint32_t DC_TYPE=DACT_MOD_TYPE_COMP; 46 void *DC_ALGO=comp_textrle_algo; 47 char *DC_NAME="Text RLE Compression (MOD)"; 48 #endif 49 50 int comp_textrle_algo(int mode, unsigned char *prev_block, unsigned char *curr_block, char *out_block, int blk_size, int bufsize) { 51 switch(mode) { 52 case DACT_MODE_COMPR: 53 return(comp_textrle_compress(prev_block, curr_block, out_block, blk_size, bufsize)); 54 break; /* Heh */ 55 case DACT_MODE_DECMP: 56 return(comp_textrle_decompress(prev_block, curr_block, out_block, blk_size, bufsize)); 57 break; 58 default: 59 printf("Unsupported mode: %i\n", mode); 60 return(-1); 61 } 62 } 63 64 int comp_textrle_compress(unsigned char *prev_block, unsigned char *curr_block, char *out_block, int blk_size, int bufsize) { 65 int i,x=0,m; 66 unsigned char sentinel=0xff; 67 unsigned char currchar=0, prevchar; 68 unsigned char charcnt=0; 69 unsigned int lowestcnt=0xffff; 70 unsigned int count[256]; 71 72 for (i=0;i<256;i++) count[i]=0; 73 74 for (i=0;i<blk_size;i++) count[curr_block[i]]++; 75 76 for (i=0;i<256;i++) { 77 if (count[i]<lowestcnt) { 78 sentinel=i; 79 lowestcnt=count[i]; 80 } 81 } 82 83 out_block[x++]=sentinel; 84 85 86 87 return(x); 88 } 89 90 int comp_textrle_decompress(unsigned char *prev_block, unsigned char *curr_block, char *out_block, int blk_size, int bufsize) { 91 int i,x=0,m; 92 unsigned char sentinel=curr_block[0]; 93 unsigned char currchar; 94 unsigned char charcnt; 95 96 for (i=1;i<blk_size;i++) { 97 currchar=curr_block[i]; 98 if (currchar==sentinel) { 99 currchar=curr_block[++i]; 100 charcnt=curr_block[++i]; 101 if ((x+charcnt)>bufsize) { 102 printf("Error in RLE compression!\n"); 103 return(0); 104 } 105 for (m=0;m<charcnt;m++) out_block[x++]=currchar; 106 } else { 107 out_block[x++]=currchar; 108 } 109 } 110 return(x); 111 } |