54 lines
1.2 KiB
C
54 lines
1.2 KiB
C
/* expand.c -- Byte Pair Encoding decompression */
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/* Copyright 1996 Philip Gage */
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/* Byte Pair Compression appeared in the September 1997
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* issue of C/C++ Users Journal. The original source code
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* may still be found at the web site of the magazine
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* (www.cuj.com).
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*
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* The decompressor has been modified by me (Thiadmer
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* Riemersma) to accept a string as input, instead of a
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* complete file.
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*/
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#include "embryo_cc_sc.h"
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#define STACKSIZE 16
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int
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strexpand(char *dest, unsigned char *source, int maxlen, unsigned char pairtable[128][2])
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{
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unsigned char stack[STACKSIZE];
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short c, top = 0;
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int len;
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len = 1; /* already 1 byte for '\0' */
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for (;;)
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{
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/* Pop byte from stack or read byte from the input string */
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if (top)
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c = stack[--top];
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else if ((c = *(unsigned char *)source++) == '\0')
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break;
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/* Push pair on stack or output byte to the output string */
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if (c > 127)
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{
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stack[top++] = pairtable[c - 128][1];
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stack[top++] = pairtable[c - 128][0];
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}
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else
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{
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len++;
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if (maxlen > 1)
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{
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*dest++ = (char)c;
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maxlen--;
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}
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}
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}
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*dest = '\0';
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return len;
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}
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