Created
June 3, 2016 13:29
-
-
Save Bulat-Ziganshin/933c3485eacc2395617bd7a17d4517f5 to your computer and use it in GitHub Desktop.
SRC from OpenBWT 2.0
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
/* | |
* srcoder.c for the OpenBWT project | |
* Copyright (c) 2008-2010 Yuta Mori. All Rights Reserved. | |
* | |
* Permission is hereby granted, free of charge, to any person | |
* obtaining a copy of this software and associated documentation | |
* files (the "Software"), to deal in the Software without | |
* restriction, including without limitation the rights to use, | |
* copy, modify, merge, publish, distribute, sublicense, and/or sell | |
* copies of the Software, and to permit persons to whom the | |
* Software is furnished to do so, subject to the following | |
* conditions: | |
* | |
* The above copyright notice and this permission notice shall be | |
* included in all copies or substantial portions of the Software. | |
* | |
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, | |
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES | |
* OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND | |
* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT | |
* HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, | |
* WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING | |
* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR | |
* OTHER DEALINGS IN THE SOFTWARE. | |
*/ | |
#if defined(HAVE_CONFIG_H) | |
# include "config.h" | |
#endif | |
#include <assert.h> | |
#include <stdio.h> | |
#if defined(HAVE_STDLIB_H) | |
# include <stdlib.h> | |
#else | |
# if defined(HAVE_MEMORY_H) | |
# include <memory.h> | |
# endif | |
#endif | |
#include "openbwt.h" | |
/*--- Sorted Rank Coding ---*/ | |
static | |
int | |
srcoder_preprocess(const int *C, unsigned char *A) { | |
int a, b, c, h; | |
unsigned char t; | |
for(a = 0, c = 0; a < 256; ++a) { if(0 < C[a]) { A[c++] = (unsigned char)a; } } | |
for(h = 4; h < c; h = h * 3 + 1) { } | |
do { | |
h /= 3; | |
for(a = h; a < c; ++a) { | |
t = A[a]; | |
for(b = a - h; | |
(0 <= b) && ((C[A[b]] < C[t]) || ((C[t] == C[A[b]]) && (t < A[b]))); | |
b -= h) { | |
A[b + h] = A[b]; | |
} | |
A[b + h] = t; | |
} | |
} while(h != 1); | |
return c; | |
} | |
void | |
obwt_srcoder_encode(const unsigned char *T, unsigned char *RCV, int *C, int n) { | |
int P[256]; | |
unsigned char A[256], S2R[256], R2S[256]; | |
int i, j, p; | |
int a, b; | |
unsigned char c, r; | |
/* find first symbols and count occurrences */ | |
for(a = 0; a < 256; ++a) { C[a] = 0; } | |
for(i = 0, b = 0; i < n; i = j) { | |
for(c = T[i], j = i + 1; (j < n) && (T[j] == c); ++j) { } | |
if(C[c] == 0) { S2R[R2S[b] = c] = (unsigned char)b; b++; } | |
C[c] += j - i; | |
} | |
/* init arrays */ | |
b = srcoder_preprocess(C, A); | |
for(a = 0, i = 0; a < b; ++a) { | |
c = A[a]; | |
P[c] = i; | |
i += C[c]; | |
} | |
/* encoding */ | |
for(i = 0; i < n; i = j) { | |
c = T[i], r = S2R[c], p = P[c]; | |
RCV[p++] = r; | |
if(0 < r) { | |
do { S2R[R2S[r] = R2S[r - 1]] = r; } while(0 < --r); | |
S2R[R2S[0] = c] = 0; | |
} | |
for(j = i + 1; (j < n) && (T[j] == c); ++j, ++p) { RCV[p] = 0; } | |
P[c] = p; | |
} | |
} | |
void | |
obwt_srcoder_decode(const unsigned char *RCV, const int *C, unsigned char *T, int n) { | |
int P[256], Q[256]; | |
unsigned char A[256], R2S[256]; | |
int i; | |
int a, b; | |
unsigned char c, r, s; | |
/* init arrays */ | |
b = srcoder_preprocess(C, A); | |
for(a = 0, i = 0; a < b; ++a) { | |
c = A[a]; | |
R2S[RCV[i]] = c; | |
P[c] = i + 1; | |
i += C[c]; | |
Q[c] = i; | |
} | |
/* decoding */ | |
for(i = 0, c = R2S[0]; i < n; ++i) { | |
T[i] = c; | |
if(P[c] < Q[c]) { | |
if(0 < (r = RCV[P[c]++])) { | |
s = 0; do { R2S[s] = R2S[s + 1]; } while(++s < r); | |
R2S[r] = c; | |
c = R2S[0]; | |
} | |
} else { | |
if(0 < --b) { | |
s = 0; do { R2S[s] = R2S[s + 1]; } while(++s < b); | |
c = R2S[0]; | |
} | |
} | |
} | |
} |
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment