shithub: jbig2

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Work-in-progress commit of huffman text region support. Fix a number
of bugs in jbig2_huffman_get_bits() and implement symbol id huffman
table decode (a custom table is always included inline in the text
region segment header.)

However, the constructed table gives an out-of-bounds symbol id on
the first read with the UBC test file.


git-svn-id: http://svn.ghostscript.com/jbig2dec/trunk@432 ded80894-8fb9-0310-811b-c03f3676ab4d

--- a/jbig2_huffman.c

+++ b/jbig2_huffman.c

@@ -90,6 +90,7 @@

 /** debug routines **/

 #ifdef JBIG2_DEBUG

+#include <stdio.h>

 /** print current huffman state */

 void jbig2_dump_huffman_state(Jbig2HuffmanState *hs)

 {

@@ -175,9 +176,18 @@

   int32_t result;

   result = this_word >> (32 - bits);

-  hs->this_word = (this_word << bits) |

-	(hs->next_word >> (32 - bits));

   hs->offset_bits += bits;

+  if (hs->offset_bits >= 32) {

+    hs->offset += 4;

+    hs->offset_bits -= 32;

+    hs->this_word = hs->next_word;

+    hs->next_word = hs->ws->get_next_word(hs->ws, hs->offset + 4);

+    hs->this_word = (hs->this_word << hs->offset_bits) |

+	(hs->next_word >> (32 - hs->offset_bits));

+  } else {

+    hs->this_word = (this_word << bits) |

+	(hs->next_word >> (32 - hs->offset_bits));

+  }

   return result;

 }

--- a/jbig2_text.c

+++ b/jbig2_text.c

@@ -157,7 +157,7 @@

 	Jbig2HuffmanLine runcodelengths[35];

 	Jbig2HuffmanLine *symcodelengths;

 	Jbig2HuffmanParams symcodeparams;

-	int code, err, range, r;

+	int code, err, len, range, r;

 	jbig2_error(ctx, JBIG2_SEVERITY_DEBUG, segment->number,

 	  "huffman coded text region");

@@ -173,7 +173,7 @@

 	  runcodelengths[index].RANGELEN = 0;

 	  runcodelengths[index].RANGELOW = index;

 	  jbig2_error(ctx, JBIG2_SEVERITY_DEBUG, segment->number,

-	    "  read runcode%d length %d", index, runcodelengths[index]);

+	    "  read runcode%d length %d", index, runcodelengths[index].PREFLEN);

 	}

 	runcodeparams.HTOOB = 0;

 	runcodeparams.lines = runcodelengths;

@@ -193,20 +193,34 @@

 	    "memory allocation failure reading symbol ID huffman table!");

 	  return -1;

 	}

-	for (index = 0; index < SBNUMSYMS; index++) {

+	index = 0;

+	while (index < SBNUMSYMS) {

 	  code = jbig2_huffman_get(hs, runcodes, &err);

 	  if (err != 0 || code < 0 || code >= 35) {

 	    jbig2_error(ctx, JBIG2_SEVERITY_FATAL, segment->number,

 	      "error reading symbol ID huffman table!");

-	    return err;

+	    return err ? err : -1;

 	  }

-	  if (code < 32) range = 0;

-	  else if (code == 32) range = jbig2_huffman_get_bits(hs, 2);

-	  else if (code == 34) range = jbig2_huffman_get_bits(hs, 3);

-	  else if (code == 35) range = jbig2_huffman_get_bits(hs, 7);

-	  for (r = 0; r < range + 1; r++) {

-	    symcodelengths[index+r].PREFLEN = code; 

+	  if (code < 32) {

+	    len = code;

+	    range = 1;

+	  } else {

+	    if (index < 1) {

+	      jbig2_error(ctx, JBIG2_SEVERITY_FATAL, segment->number,

+		"error decoding symbol id table: run length with no antecedent!");

+	      /* todo: memory cleanup */

+	      return -1;

+	    }

+	    len = symcodelengths[index-1].PREFLEN;

+	    if (code == 32) range = jbig2_huffman_get_bits(hs, 2) + 3;

+	    else if (code == 33) range = jbig2_huffman_get_bits(hs, 3) + 3;

+	    else if (code == 34) range = jbig2_huffman_get_bits(hs, 7) + 11;

+	  }

+	  jbig2_error(ctx, JBIG2_SEVERITY_DEBUG, segment->number,

+	    "  read runcode%d at index %d (length %d range %d)", code, index, len, range);

+	  for (r = 0; r < range; r++) {

+	    symcodelengths[index+r].PREFLEN = len; 

 	    symcodelengths[index+r].RANGELEN = 0; 

 	    symcodelengths[index+r].RANGELOW = index;

 	  }