ff881377d8
Fix a clang warning which is also a bug. Thanks to @marcespie for the patch. Fixes upstream issue #3
342 lines
7.0 KiB
C
342 lines
7.0 KiB
C
/*
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* tumble: build a PDF file from image files
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*
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* G4 compression
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* Copyright 2003, 2017 Eric Smith <spacewar@gmail.com>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation. Note that permission is
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* not granted to redistribute this program under the terms of any
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* other version of the General Public License.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111 USA
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*
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* 2007-06-20 [JDB] Fixed a bug wherein "g4_get_pixel" is called with pixel
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* index == width, causing an index off the end of the array
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* if width % BITS_PER_WORD == 0.
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*/
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#define G4_DEBUG 0
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#include <stdbool.h>
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#include <stdint.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include "bitblt.h"
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#include "bitblt_tables.h"
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#include "pdf_util.h"
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#include "g4_tables.h"
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#define BIT_BUF_SIZE 4096
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struct bit_buffer
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{
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FILE *f;
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uint32_t byte_idx; /* index to next byte position in data buffer */
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uint32_t bit_idx; /* one greater than the next bit position in data buffer,
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8 = MSB, 1 = LSB */
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uint8_t data [BIT_BUF_SIZE];
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};
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static void init_bit_buffer (struct bit_buffer *buf)
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{
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buf->byte_idx = 0;
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buf->bit_idx = 8;
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memset (& buf->data [0], 0, BIT_BUF_SIZE);
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}
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static void flush_bits (struct bit_buffer *buf)
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{
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size_t s;
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if (buf->bit_idx != 8)
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{
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buf->byte_idx++;
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buf->bit_idx = 8;
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}
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s = fwrite (& buf->data [0], 1, buf->byte_idx, buf->f);
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/* $$$ should check result */
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init_bit_buffer (buf);
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}
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static void advance_byte (struct bit_buffer *buf)
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{
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buf->byte_idx++;
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buf->bit_idx = 8;
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if (buf->byte_idx == BIT_BUF_SIZE)
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flush_bits (buf);
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}
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static void write_bits (struct bit_buffer *buf,
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uint32_t count,
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uint32_t bits)
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{
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while (count > buf->bit_idx)
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{
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buf->data [buf->byte_idx] |= bits >> (count - buf->bit_idx);
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count -= buf->bit_idx;
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advance_byte (buf);
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}
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bits &= ((1 << count) - 1);
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buf->data [buf->byte_idx] |= bits << (buf->bit_idx - count);
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buf->bit_idx -= count;
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if (buf->bit_idx == 0)
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advance_byte (buf);
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}
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static void g4_encode_horizontal_run (struct bit_buffer *buf,
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bool black,
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uint32_t run_length)
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{
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uint32_t i;
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while (run_length >= 2560)
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{
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write_bits (buf, 12, 0x01f);
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run_length -= 2560;
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}
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if (run_length >= 1792)
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{
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i = (run_length - 1792) >> 6;
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write_bits (buf,
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g4_long_makeup_code [i].count,
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g4_long_makeup_code [i].bits);
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run_length -= (1792 + (i << 6));
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}
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else if (run_length >= 64)
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{
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i = (run_length >> 6) - 1;
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write_bits (buf,
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g4_makeup_code [black] [i].count,
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g4_makeup_code [black] [i].bits);
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run_length -= (i + 1) << 6;
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}
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write_bits (buf,
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g4_h_code [black] [run_length].count,
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g4_h_code [black] [run_length].bits);
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}
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static inline int g4_get_pixel (uint8_t *buf, uint32_t x)
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{
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return ((buf [x >> 3] >> (x & 7)) & 1);
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}
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#define not_aligned(p) (((word_t) p) & (sizeof (word_t) - 1))
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static uint32_t g4_find_pixel (uint8_t *buf,
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uint32_t pos,
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uint32_t width,
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bool color)
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{
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uint8_t *p = buf + pos / 8;
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int bit = pos & 7;
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uint8_t *max_p = buf + (width - 1) / 8;
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uint8_t d;
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/* check first byte (may be partial) */
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d = *p;
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if (! color)
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d = ~d;
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bit += rle_tab [bit][d];
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if (bit < 8)
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goto done;
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p++;
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/* check individual bytes until we hit word alignment */
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while ((p <= max_p) && not_aligned (p))
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{
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d = *p;
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if (! color)
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d = ~d;
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if (d != 0)
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goto found;
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p++;
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}
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/* check aligned words in middle */
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while ((p <= (max_p - sizeof (word_t))))
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{
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word_t w = *((word_t *) p);
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if (! color)
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w = ~w;
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if (w != 0)
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break;
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p += sizeof (word_t);
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}
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/* check trailing bytes */
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while (p <= max_p)
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{
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d = *p;
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if (! color)
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d = ~d;
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if (d)
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goto found;
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p++;
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}
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goto not_found;
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found:
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bit = rle_tab [0][d];
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done:
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pos = ((p - buf) << 3) + bit;
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if (pos < width)
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return (pos);
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not_found:
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return (width);
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}
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#define absdiff(a, b) ((a) < (b) ? (b)-(a) : (a) - (b))
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static void g4_encode_row (struct bit_buffer *buf,
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uint32_t width,
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uint8_t *ref,
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uint8_t *row)
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{
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uint32_t a0, a1, a2;
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uint32_t b1, b2;
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bool a0_c;
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a0 = 0;
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a0_c = 0;
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a1 = g4_find_pixel (row, 0, width, 1);
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b1 = g4_find_pixel (ref, 0, width, 1);
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#if (G4_DEBUG & 1)
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fprintf (stderr, "start of row\n");
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if ((a1 != width) || (b1 != width))
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{
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fprintf (stderr, "a1 = %u, b1 = %u\n", a1, b1);
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}
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#endif
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while (a0 < width)
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{
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b2 = g4_find_pixel (ref, b1 + 1, width, ! g4_get_pixel (ref, b1));
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if (b2 < a1)
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{
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/* pass mode - 0001 */
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write_bits (buf, 4, 0x1);
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a0 = b2;
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#if (G4_DEBUG & 1)
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fprintf (stderr, "pass\n");
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#endif
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}
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else if (absdiff(a1, b1) <= 3)
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{
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/* vertical mode */
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write_bits (buf,
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g4_vert_code [3 + a1 - b1].count,
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g4_vert_code [3 + a1 - b1].bits);
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a0 = a1;
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#if (G4_DEBUG & 1)
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fprintf (stderr, "vertical %d\n", a1 - b1);
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#endif
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}
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else
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{
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/* horizontal mode - 001 */
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a2 = g4_find_pixel (row, a1 + 1, width, a0_c);
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write_bits (buf, 3, 0x1);
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g4_encode_horizontal_run (buf, a0_c, a1 - a0);
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g4_encode_horizontal_run (buf, ! a0_c, a2 - a1);
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#if (G4_DEBUG & 1)
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fprintf (stderr, "horizontal %d %s, %d %s\n",
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a1 - a0, a0_c ? "black" : "white",
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a2 - a1, a0_c ? "white" : "black");
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#endif
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a0 = a2;
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}
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if (a0 >= width)
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break;;
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a0_c = g4_get_pixel (row, a0);
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a1 = g4_find_pixel (row, a0 + 1, width, ! a0_c);
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b1 = g4_find_pixel (ref, a0 + 1, width, ! g4_get_pixel (ref, a0));
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if (g4_get_pixel (ref, b1) == a0_c)
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b1 = g4_find_pixel (ref, b1 + 1, width, ! a0_c);
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#if (G4_DEBUG & 1)
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fprintf (stderr, "a1 = %u, b1 = %u\n", a1, b1);
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#endif
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}
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}
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void bitblt_write_g4 (Bitmap *bitmap, FILE *f)
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{
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uint32_t width = bitmap->rect.max.x - bitmap->rect.min.x;
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uint32_t row;
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struct bit_buffer bb;
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word_t *temp_buffer;
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word_t *cur_line;
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word_t *ref_line; /* reference (previous) row */
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temp_buffer = pdf_calloc (width / BITS_PER_WORD + 1,
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sizeof (word_t));
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cur_line = bitmap->bits;
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ref_line = temp_buffer;
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init_bit_buffer (& bb);
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bb.f = f;
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for (row = bitmap->rect.min.y;
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row < bitmap->rect.max.y;
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row++)
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{
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g4_encode_row (& bb,
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width,
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(uint8_t *) ref_line,
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(uint8_t *) cur_line);
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ref_line = cur_line;
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cur_line += bitmap->row_words;
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}
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/* write EOFB code */
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write_bits (& bb, 24, 0x001001);
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flush_bits (& bb);
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free (temp_buffer);
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}
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