Initial import of the CDE 2.1.30 sources from the Open Group.
This commit is contained in:
Peter Howkins
291
cde/lib/DtSearch/hdecode.c
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291
cde/lib/DtSearch/hdecode.c
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/*
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* COMPONENT_NAME: austext
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*
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* FUNCTIONS: hc_decode
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* main
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*
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* ORIGINS: 27
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*
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*
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* (C) COPYRIGHT International Business Machines Corp. 1990,1995
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* All Rights Reserved
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* Licensed Materials - Property of IBM
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* US Government Users Restricted Rights - Use, duplication or
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* disclosure restricted by GSA ADP Schedule Contract with IBM Corp.
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*/
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/************************* HDECODE.C ***************************
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* $XConsortium: hdecode.c /main/8 1996/11/21 19:50:15 drk $
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* 1990.
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* Decode function that reads in a Huffman Code bitstring and returns the
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* original plaintext characters. Intended use of Huffman Code is
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* both compression and encryption of text lines in Opera System.
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* Decode (decryption) is optimized for high speed, online use.
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*
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* Global Arguments:
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* 'hctree' is decode table in form of array of integers.
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* Each integer pair forms a node in a huffman code tree.
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* See huffcode.c for full discussion of its organization.
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* If 'hctree' is NULL, the tree has not been linked into
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* current object module, and this function must read the
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* source file and create the tree at execution time.
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* This flexibility allows internal use of decode function
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* using different trees without having to recompile/relink.
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* The linked-in version is more secure for external customer use.
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* 'hctree_name' is filename prefix for both encode (.huf) and
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* encode (.c) source files. If 'hctree' is NULL, this is
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* the file from which the tree will be built.
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* 'hctree_id' is unique unix timestamp indicating when hctree was
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* create. It is compared with caller's (encoder's) passed stamp
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* to ensure encode/decode compatibility.
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* 'hctree_root' is the integer index of the root node in hctree.
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* By luck, this is always the LAST node so it also gives an
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* indication of the storage needed when the tree has to be
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* allocated at execution time.
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*
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* Passed Arguments:
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* 'bitstring' is the address of the huffman encoded cyphertext.
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* It begins on byte boundary, but may end in middle of
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* a byte depending on charcount.
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* 'charbuf' is the output buffer where the plaintext characters
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* will be assembled.
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* 'charcount' is the number of plaintext bytes that were encoded into
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* the passed bitstring, and will be assembled into charbuf.
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*
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* $Log$
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* Revision 2.3 1996/03/13 22:56:26 miker
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* Changed char to UCHAR several places.
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*
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* Revision 2.2 1995/10/25 17:51:46 miker
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* Added prolog.
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*
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* Revision 2.1 1995/09/22 20:50:00 miker
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* Freeze DtSearch 0.1, AusText 2.1.8
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*
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* Revision 1.3 1995/09/05 18:02:21 miker
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* Name changes for DtSearch.
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*/
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#include "SearchP.h"
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#include <errno.h>
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#define X_INCLUDE_STRING_H
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#define XOS_USE_NO_LOCKING
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#include <X11/Xos_r.h>
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#define HDEC_FBUFSZ 128
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#define PROGNAME "HDECODE"
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#define MS_huff 30 /* message catalog set number */
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extern char *hctree_name;
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extern time_t hctree_id;
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extern int hctree_root;
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extern int *hctree;
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/*---------------- TREENODE structure ---------------------*/
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typedef struct {
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int branch0;
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int branch1;
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} TREENODE;
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/************************************************/
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/* */
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/* HC Decode */
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/* */
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/************************************************/
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void hc_decode (
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UCHAR *bitstring, /* input: compressed data */
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UCHAR *charbuf, /* output: uncompressed data */
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int charcount, /* input: length uncompressed data */
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time_t encode_id)
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{ /* input: compression table to use */
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#ifdef DEBUG_DECODE
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static int first_time = TRUE;
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#endif
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register int bitreg;
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int i;
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int bitcount;
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int tree_index;
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TREENODE *tree_addr;
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#ifdef EXTERNAL_TREE
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char *ptr;
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char *hdecode_filebuf;
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FILE *hdecode_file;
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_Xstrtokparams strtok_buf;
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#endif
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#ifdef EXTERNAL_TREE
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/* Create hctree from external file? */
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if (hctree == NULL) {
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if ((hdecode_filebuf = malloc (HDEC_FBUFSZ)) == NULL) {
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fprintf (aa_stderr, catgets(dtsearch_catd, MS_huff, 10,
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"%s Out of Memory.\n"),
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PROGNAME"076");
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DtSearchExit (2);
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}
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if ((hdecode_file = fopen (hctree_name, "r")) == NULL) {
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fprintf (aa_stderr, catgets(dtsearch_catd, MS_huff, 11,
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"%s Cannot open tree file '%s': %s\n"),
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PROGNAME"082", hctree_name, strerror (errno));
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DtSearchExit (2);
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}
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/* read first few lines to load global variables */
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for (i = 0; i < 3; i++)
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fgets (hdecode_filebuf, HDEC_FBUFSZ, hdecode_file);
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ptr = strchr (hdecode_filebuf, '=');
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hctree_id = atol (ptr + 1);
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fgets (hdecode_filebuf, HDEC_FBUFSZ, hdecode_file);
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ptr = strchr (hdecode_filebuf, '=');
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hctree_root = atoi (ptr + 1);
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fgets (hdecode_filebuf, HDEC_FBUFSZ, hdecode_file); /* throwaway */
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/* allocate space for the hctree and read in the values */
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if ((hctree = (int *) malloc (
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sizeof (int) * 2 * (hctree_root + 2))) == NULL) {
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fprintf (aa_stderr, "\n" PROGNAME "100 Out of Memory.\7\n");
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DtSearchExit (2);
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}
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for (i = 0; i <= hctree_root; i++) {
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if ((fgets (hdecode_filebuf, HDEC_FBUFSZ, hdecode_file)) == NULL) {
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fprintf (aa_stderr, catgets(dtsearch_catd, MS_huff, 12,
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"%s Invalid format hctree '%s'.\n"),
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PROGNAME"106", hctree_name);
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DtSearchExit (2);
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}
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hctree[2 * i] = atoi (_XStrtok (hdecode_filebuf, " \t,", strtok_buf));
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hctree[2 * i + 1] = atoi (_XStrtok (NULL, " \t,", strtok_buf));
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}
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free (hdecode_filebuf);
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fclose (hdecode_file);
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} /* endif where hctree created from external file */
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#endif /* for EXTERNAL_TREE */
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#ifdef DEBUG_DECODE
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if (first_time) {
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first_time = FALSE;
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printf ("\n***** created hctree from '%s' ******\n"
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"hctree_id = %ld\nhctree_root = %d\n",
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hctree_name, hctree_id, hctree_root);
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}
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#endif
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if (encode_id != hctree_id) {
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fprintf (aa_stderr, catgets(dtsearch_catd, MS_huff, 13,
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"%s Incompatible hctree_ids.\n"),
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PROGNAME"118");
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DtSearchExit (2);
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}
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tree_addr = (TREENODE *) hctree;
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bitcount = 0;
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while (charcount-- > 0) { /****** MAIN OUTPUT CHARACTER LOOP ******/
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tree_index = hctree_root;
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while (tree_index >= 0) { /****** TREE TRAVERSAL LOOP ******/
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/* retrieve next bit */
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if (bitcount <= 0) { /* read next input char? */
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bitcount = 8;
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bitreg = *bitstring++;
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}
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bitreg <<= 1;
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bitcount--;
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if (bitreg & 0x0100)
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tree_index = tree_addr[tree_index].branch1;
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else
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tree_index = tree_addr[tree_index].branch0;
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} /* end tree traversal loop */
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/******** DECODE CHARACTER ********/
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/* if literal code, retrieve next 8 bits as char itself */
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if ((tree_index += 257) == 256) {
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tree_index = 0;
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for (i = 8; i > 0; i--) {
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if (bitcount <= 0) { /* read next input char? */
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bitcount = 8;
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bitreg = *bitstring++;
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}
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bitreg <<= 1;
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bitcount--;
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tree_index <<= 1;
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if (bitreg & 0x0100)
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tree_index |= 1;
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} /* end 8-bit for loop */
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} /* endif to process literal coding */
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*charbuf = tree_index;
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charbuf++;
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} /* end main output character loop */
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return;
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} /* end of function hc_decode */
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#ifdef DEBUG_DECODE
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/************************************************/
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/* */
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/* Main */
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/* */
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/************************************************/
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void main (int argc, char *argv[])
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{
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#define BITSTR_BUFSIZE 140
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FILE *instream;
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FILE *aa_stderr = stderr;
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char stringbuf[BITSTR_BUFSIZE + 2];
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char charbuf[9 * BITSTR_BUFSIZE];
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char fname_tree[80];
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int mychar;
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int oops;
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int i;
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union {
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INT integer;
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char chars[2];
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} charcount;
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if (argc <= 1) {
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puts ("Usage: hdecode [hucfile] cypherfile");
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return;
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}
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if (argc >= 3) {
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hctree = NULL;
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append_ext (fname_tree, sizeof (fname_tree), argv[1], EXT_HDECODE);
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hctree_name = fname_tree;
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argv++;
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}
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if ((instream = fopen (argv[1], "rb")) == NULL) {
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fprintf (aa_stderr, "Cannot open cypherfile '%s'.\n", argv[1]);
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exit (2);
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}
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MAINLOOP:
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/**************/
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if ((mychar = fgetc (instream)) == EOF)
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return;
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charcount.chars[0] = mychar;
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if ((mychar = fgetc (instream)) == EOF)
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return;
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charcount.chars[1] = mychar;
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if (charcount.integer > sizeof (charbuf) - 2) {
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oops = TRUE;
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charcount.integer = sizeof (charbuf) - 2;
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}
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else
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oops = FALSE;
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/* printf("\n\n***** charcount = %d %s*****\n",
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charcount.integer, (oops) ? "(reduced)" : "");*/
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for (i = 0; i < BITSTR_BUFSIZE; i++) {
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if ((mychar = fgetc (instream)) == EOF) {
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fprintf (aa_stderr, "\n" PROGNAME "202 Unexpected EOF '%s'.\n",
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argv[1]);
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exit (2);
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}
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stringbuf[i] = mychar;
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}
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hc_decode (stringbuf, charbuf, charcount.integer, hctree_id);
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for (i = 0; i < charcount.integer; i++)
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putchar (charbuf[i]);
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goto MAINLOOP;
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/************/
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} /* end of function main */
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#endif
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/************************* HDECODE.C ***************************/
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