/* expand.c -- Byte Pair Encoding decompression */

 /* Copyright 1996 Philip Gage */

 /* Byte Pair Compression appeared in the September 1997

  * issue of C/C++ Users Journal. The original source code

  * may still be found at the web site of the magazine

  * (www.cuj.com).

  *

  * The decompressor has been modified by me (Thiadmer

  * Riemersma) to accept a string as input, instead of a

  * complete file.

  */

 #include <assert.h>

 #include <stdio.h>

 #include "sc.h"

 #define STACKSIZE 16

 SC_FUNC int strexpand(char *dest, unsigned char *source, int maxlen, unsigned char pairtable[128][2])

 {

   unsigned char stack[STACKSIZE];

   short c, top = 0;

   int len;

   assert(maxlen > 0);

   len = 1;              /* already 1 byte for '\0' */

   for (;;) {

     /* Pop byte from stack or read byte from the input string */

     if (top)

       c = stack[--top];

     else if ((c = *(unsigned char *)source++) == '\0')

       break;

     /* Push pair on stack or output byte to the output string */

     if (c > 127) {

       assert(top+2 <= STACKSIZE);

       stack[top++] = pairtable[c-128][1];

       stack[top++] = pairtable[c-128][0];

     }

     else {

       len++;

       if (maxlen > 1) { /* reserve one byte for the '\0' */

         *dest++ = (char)c;

         maxlen--;

       }

     }

   }

   *dest = '\0';

   return len;           /* return number of bytes decoded */

 }

 #if 0 /*for testing*/

 #include "sc5.scp"

 int main (int argc, char **argv)

 {

   int i;

   char str[128];

   for (i=0; i<58; i++) {

     strexpand(str, errmsg[i], sizeof str, SCPACK_TABLE);

     printf("%s", str);

   } /* for */

   return 0;

 }

 #endif