optimized g4_find_pixel().
This commit is contained in:
Eric Smith
parent
4a2d824d07
commit
59d9944997
107
bitblt_g4.c
107
bitblt_g4.c
@ -4,7 +4,7 @@
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* will be compressed using ITU-T T.6 (G4) fax encoding.
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*
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* G4 compression
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* $Id: bitblt_g4.c,v 1.11 2003/03/11 03:14:39 eric Exp $
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* $Id: bitblt_g4.c,v 1.12 2003/03/12 02:59:29 eric Exp $
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* Copyright 2003 Eric Smith <eric@brouhaha.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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@ -35,6 +35,7 @@
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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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@ -69,15 +70,6 @@ static void flush_bits (struct bit_buffer *buf)
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buf->byte_idx++;
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buf->bit_idx = 8;
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}
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#if (G4_DEBUG >= 3)
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{
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int i;
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fprintf (stderr, "::: ");
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for (i = 0; i < buf->byte_idx; i++)
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fprintf (stderr, "%02x ", buf->data [i]);
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fprintf (stderr, "\n");
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}
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#endif
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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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@ -97,16 +89,6 @@ 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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#if (G4_DEBUG >= 2)
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{
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int i;
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fprintf (stderr, "%d %04x: ", count, bits);
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for (i = count - 1; i >= 0; i--)
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fprintf (stderr, "%d", (bits >> i) & 1);
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fprintf (stderr, "\n");
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}
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#endif
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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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@ -163,17 +145,72 @@ static inline int g4_get_pixel (uint8_t *buf, uint32_t x)
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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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while (pos < width)
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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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if (g4_get_pixel (buf, pos) == color)
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return (pos);
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pos++;
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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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@ -194,7 +231,7 @@ static void g4_encode_row (struct bit_buffer *buf,
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b1 = g4_find_pixel (ref, 0, width, 1);
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#if G4_DEBUG
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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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@ -211,7 +248,7 @@ static void g4_encode_row (struct bit_buffer *buf,
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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
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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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@ -222,7 +259,7 @@ static void g4_encode_row (struct bit_buffer *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
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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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@ -233,7 +270,7 @@ static void g4_encode_row (struct bit_buffer *buf,
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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
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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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@ -250,7 +287,7 @@ static void g4_encode_row (struct bit_buffer *buf,
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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
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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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@ -263,17 +300,13 @@ void bitblt_write_g4 (Bitmap *bitmap, FILE *f)
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uint32_t row;
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struct bit_buffer bb;
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word_type *temp_buffer;
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word_t *temp_buffer;
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word_type *cur_line;
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word_type *ref_line; /* reference (previous) row */
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#if G4_DEBUG
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fprintf (stderr, "width %u\n", width);
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#endif
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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) / BITS_PER_WORD,
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sizeof (word_type));
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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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