ref: 4be0d08eaeb704454a7bf1dc95e7b6739fface4e
parent: 01736665634a1be9b07b275a5a365b56f445d965
author: giles <giles@ded80894-8fb9-0310-811b-c03f3676ab4d>
date: Tue May 20 06:31:54 EDT 2003
Complete implementation of mmr decoding. We now pass another of the ubc test bitstreams! (042_3.jb2, mmr generic region) Patch from Tor Andersson. git-svn-id: http://svn.ghostscript.com/jbig2dec/trunk@253 ded80894-8fb9-0310-811b-c03f3676ab4d
--- a/jbig2_mmr.c
+++ b/jbig2_mmr.c
@@ -1,7 +1,7 @@
/*
jbig2dec
- Copyright (C) 2001-2002 artofcode LLC.
+ Copyright (C) 2001-2003 artofcode LLC.
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
@@ -51,12 +51,12 @@
mmr->height = height;
mmr->data = data;
mmr->size = size;
+
mmr->data_index = 0;
mmr->bit_index = 0;
for (i = 0; i < size && i < 4; i++)
word |= (data[i] << ((3 - i) << 3));
mmr->word = word;
-
}
static void
@@ -73,9 +73,23 @@
}
}
+/*
+<raph> the first 2^(initialbits) entries map bit patterns to decodes
+<raph> let's say initial_bits is 8 for the sake of example
+<raph> and that the code is 1001
+<raph> that means that entries 0x90 .. 0x9f have the entry { val, 4 }+<raph> because those are all the bytes that start with the code
+<raph> and the 4 is the length of the code
+... if (n_bits > initial_bits) ...
+<raph> anyway, in that case, it basically points to a mini table
+<raph> the n_bits is the maximum length of all codes beginning with that byte
+<raph> so 2^(n_bits - initial_bits) is the size of the mini-table
+<raph> peter came up with this, and it makes sense
+*/
+
typedef struct {- int val;
- int n_bits;
+ short val;
+ short n_bits;
} mmr_table_node;
/* white decode table (runlength huffman codes) */
@@ -710,7 +724,76 @@
{ 0, 3 }};
+#define getbit(buf, x) ( ( buf[x >> 3] >> ( 7 - (x & 7) ) ) & 1 )
+
static int
+jbig2_find_changing_element(const byte *line, int x, int w)
+{+ int a, b;
+
+ if (line == 0)
+ return w;
+
+ if (x == 0)
+ {+ a = 0;
+ }
+ else
+ {+ a = getbit(line, x);
+ x ++;
+ }
+
+ while (x < w)
+ {+ b = getbit(line, x);
+ if (a != b)
+ break;
+ x++;
+ }
+
+ return x;
+}
+
+static int
+jbig2_find_changing_element_of_color(const byte *line, int x, int w, int color)
+{+ if (line == 0)
+ return w;
+ x = jbig2_find_changing_element(line, x, w);
+ if (x < w && getbit(line, x) != color)
+ x = jbig2_find_changing_element(line, x, w);
+ return x;
+}
+
+static const byte lm[8] = { 0xFF, 0x7F, 0x3F, 0x1F, 0x0F, 0x07, 0x03, 0x01 };+static const byte rm[8] = { 0x00, 0x80, 0xC0, 0xE0, 0xF0, 0xF8, 0xFC, 0xFE };+
+static void
+jbig2_set_bits(byte *line, int x0, int x1)
+{+ int a0, a1, b0, b1, a;
+
+ a0 = x0 >> 3;
+ a1 = x1 >> 3;
+
+ b0 = x0 & 7;
+ b1 = x1 & 7;
+
+ if (a0 == a1)
+ {+ line[a0] |= lm[b0] & rm[b1];
+ }
+ else
+ {+ line[a0] |= lm[b0];
+ for (a = a0 + 1; a < a1; a++)
+ line[a] = 0xFF;
+ line[a1] |= rm[b1];
+ }
+}
+
+static int
jbig2_decode_get_code(Jbig2MmrCtx *mmr, const mmr_table_node *table, int initial_bits)
{uint32_t word = mmr->word;
@@ -718,13 +801,14 @@
int val = table[table_ix].val;
int n_bits = table[table_ix].n_bits;
- if (n_bits > 8)
+ if (n_bits > initial_bits)
{int mask = (1 << (32 - initial_bits)) - 1;
table_ix = val + ((word & mask) >> (32 - n_bits));
val = table[table_ix].val;
- n_bits = 8 + table[table_ix].n_bits + 8;
+ n_bits = initial_bits + table[table_ix].n_bits;
}
+
jbig2_decode_mmr_consume(mmr, n_bits);
return val;
}
@@ -747,58 +831,119 @@
static void
jbig2_decode_mmr_line(Jbig2MmrCtx *mmr, const byte *ref, byte *dst)
{+ int a0, a1, a2, b1, b2;
+ int c;
+
+ a0 = 0;
+ c = 0; /* 0 is white, black is 1 */
+
while (1)
{uint32_t word = mmr->word;
- /* printf ("%08x\n", word); */+
+ if (a0 >= mmr->width)
+ break;
+
if ((word >> (32 - 3)) == 1)
{int white_run, black_run;
jbig2_decode_mmr_consume(mmr, 3);
- white_run = jbig2_decode_get_run(mmr, jbig2_mmr_white_decode, 8);
- black_run = jbig2_decode_get_run(mmr, jbig2_mmr_black_decode, 7);
- /* printf ("H %d %d\n", white_run, black_run); */+
+ if (c == 0)
+ {+ white_run = jbig2_decode_get_run(mmr, jbig2_mmr_white_decode, 8);
+ black_run = jbig2_decode_get_run(mmr, jbig2_mmr_black_decode, 7);
+ a1 = a0 + white_run;
+ a2 = a1 + black_run;
+ jbig2_set_bits(dst, a1, a2);
+ a0 = a2;
+ /* printf ("H %d %d\n", white_run, black_run); */+ }
+ else
+ {+ black_run = jbig2_decode_get_run(mmr, jbig2_mmr_black_decode, 7);
+ white_run = jbig2_decode_get_run(mmr, jbig2_mmr_white_decode, 8);
+ a1 = a0 + black_run;
+ a2 = a1 + white_run;
+ jbig2_set_bits(dst, a0, a1);
+ a0 = a2;
+ /* printf ("H %d %d\n", black_run, white_run); */+ }
}
+
else if ((word >> (32 - 4)) == 1)
{ /* printf ("P\n"); */- jbig2_decode_mmr_consume(mmr, 3);
+ jbig2_decode_mmr_consume(mmr, 4);
+ b1 = jbig2_find_changing_element_of_color(ref, a0, mmr->width, !c);
+ b2 = jbig2_find_changing_element(ref, b1, mmr->width);
+ if (c) jbig2_set_bits(dst, a0, b2);
+ a0 = b2;
}
+
else if ((word >> (32 - 1)) == 1)
{ /* printf ("V(0)\n"); */jbig2_decode_mmr_consume(mmr, 1);
+ b1 = jbig2_find_changing_element_of_color(ref, a0, mmr->width, !c);
+ if (c) jbig2_set_bits(dst, a0, b1);
+ a0 = b1;
+ c = !c;
}
else if ((word >> (32 - 3)) == 3)
{ /* printf ("VR(1)\n"); */jbig2_decode_mmr_consume(mmr, 3);
+ b1 = jbig2_find_changing_element_of_color(ref, a0, mmr->width, !c);
+ if (c) jbig2_set_bits(dst, a0, b1 + 1);
+ a0 = b1 + 1;
+ c = !c;
}
else if ((word >> (32 - 6)) == 3)
{ /* printf ("VR(2)\n"); */jbig2_decode_mmr_consume(mmr, 6);
+ b1 = jbig2_find_changing_element_of_color(ref, a0, mmr->width, !c);
+ if (c) jbig2_set_bits(dst, a0, b1 + 2);
+ a0 = b1 + 2;
+ c = !c;
}
else if ((word >> (32 - 7)) == 3)
{ /* printf ("VR(3)\n"); */jbig2_decode_mmr_consume(mmr, 7);
+ b1 = jbig2_find_changing_element_of_color(ref, a0, mmr->width, !c);
+ if (c) jbig2_set_bits(dst, a0, b1 + 3);
+ a0 = b1 + 3;
+ c = !c;
}
else if ((word >> (32 - 3)) == 2)
{ /* printf ("VL(1)\n"); */jbig2_decode_mmr_consume(mmr, 3);
+ b1 = jbig2_find_changing_element_of_color(ref, a0, mmr->width, !c);
+ if (c) jbig2_set_bits(dst, a0, b1 - 1);
+ a0 = b1 - 1;
+ c = !c;
}
else if ((word >> (32 - 6)) == 2)
{ /* printf ("VL(2)\n"); */jbig2_decode_mmr_consume(mmr, 6);
+ b1 = jbig2_find_changing_element_of_color(ref, a0, mmr->width, !c);
+ if (c) jbig2_set_bits(dst, a0, b1 - 2);
+ a0 = b1 - 2;
+ c = !c;
}
else if ((word >> (32 - 7)) == 2)
{ /* printf ("VL(3)\n"); */jbig2_decode_mmr_consume(mmr, 7);
+ b1 = jbig2_find_changing_element_of_color(ref, a0, mmr->width, !c);
+ if (c) jbig2_set_bits(dst, a0, b1 - 3);
+ a0 = b1 - 3;
+ c = !c;
}
else
break;
@@ -814,7 +959,8 @@
{Jbig2MmrCtx mmr;
const int rowstride = image->stride;
- const byte *gbreg_line = (const byte *)image->data;
+ byte *dst = image->data;
+ byte *ref = NULL;
int y;
jbig2_decode_mmr_init(&mmr, image->width, image->height, data, size);
@@ -821,8 +967,10 @@
for (y = 0; y < image->height; y++)
{- jbig2_decode_mmr_line(&mmr, gbreg_line, NULL);
- gbreg_line += rowstride;
+ memset(dst, 0, rowstride);
+ jbig2_decode_mmr_line(&mmr, ref, dst);
+ ref = dst;
+ dst += rowstride;
}
return 0;