Tue, 11 Mar 2003 11:14:39 +0000
many bug fixes including bit ordering of output, search positions and polarities. added G4_DEBUG conditional.
| bitblt_g4.c | file | annotate | diff | revisions |
1.1 --- a/bitblt_g4.c Mon Mar 10 13:08:25 2003 +0000 1.2 +++ b/bitblt_g4.c Tue Mar 11 11:14:39 2003 +0000 1.3 @@ -4,7 +4,7 @@ 1.4 * will be compressed using ITU-T T.6 (G4) fax encoding. 1.5 * 1.6 * G4 compression 1.7 - * $Id: bitblt_g4.c,v 1.10 2003/03/10 05:08:25 eric Exp $ 1.8 + * $Id: bitblt_g4.c,v 1.11 2003/03/11 03:14:39 eric Exp $ 1.9 * Copyright 2003 Eric Smith <eric@brouhaha.com> 1.10 * 1.11 * This program is free software; you can redistribute it and/or modify 1.12 @@ -24,6 +24,9 @@ 1.13 */ 1.14 1.15 1.16 +#define G4_DEBUG 0 1.17 + 1.18 + 1.19 #include <stdbool.h> 1.20 #include <stdint.h> 1.21 #include <stdio.h> 1.22 @@ -38,38 +41,53 @@ 1.23 #include "g4_tables.h" 1.24 1.25 1.26 -#define BIT_BUF_SIZE 4096 1.27 +#define BIT_BUF_SIZE 1 /* 4096 */ 1.28 1.29 struct bit_buffer 1.30 { 1.31 FILE *f; 1.32 uint32_t byte_idx; /* index to next byte position in data buffer */ 1.33 - uint32_t bit_idx; /* index to next bit position in data buffer, 1.34 - 0 = MSB, 7 = LSB */ 1.35 + uint32_t bit_idx; /* one greater than the next bit position in data buffer, 1.36 + 8 = MSB, 1 = LSB */ 1.37 uint8_t data [BIT_BUF_SIZE]; 1.38 }; 1.39 1.40 1.41 +static void init_bit_buffer (struct bit_buffer *buf) 1.42 +{ 1.43 + buf->byte_idx = 0; 1.44 + buf->bit_idx = 8; 1.45 + memset (& buf->data [0], 0, BIT_BUF_SIZE); 1.46 +} 1.47 + 1.48 + 1.49 static void flush_bits (struct bit_buffer *buf) 1.50 { 1.51 size_t s; 1.52 - if (buf->bit_idx) 1.53 + if (buf->bit_idx != 8) 1.54 { 1.55 - /* zero remaining bits in last byte */ 1.56 - buf->data [buf->byte_idx] &= ~ ((1 << (8 - buf->bit_idx)) - 1); 1.57 buf->byte_idx++; 1.58 - buf->bit_idx = 0; 1.59 + buf->bit_idx = 8; 1.60 } 1.61 +#if (G4_DEBUG >= 3) 1.62 + { 1.63 + int i; 1.64 + fprintf (stderr, "::: "); 1.65 + for (i = 0; i < buf->byte_idx; i++) 1.66 + fprintf (stderr, "%02x ", buf->data [i]); 1.67 + fprintf (stderr, "\n"); 1.68 + } 1.69 +#endif 1.70 s = fwrite (& buf->data [0], 1, buf->byte_idx, buf->f); 1.71 /* $$$ should check result */ 1.72 - buf->byte_idx = 0; 1.73 + init_bit_buffer (buf); 1.74 } 1.75 1.76 1.77 static void advance_byte (struct bit_buffer *buf) 1.78 { 1.79 buf->byte_idx++; 1.80 - buf->bit_idx = 0; 1.81 + buf->bit_idx = 8; 1.82 if (buf->byte_idx == BIT_BUF_SIZE) 1.83 flush_bits (buf); 1.84 } 1.85 @@ -79,24 +97,28 @@ 1.86 uint32_t count, 1.87 uint32_t bits) 1.88 { 1.89 - uint32_t b2; /* how many bits will fit in byte in data buffer */ 1.90 - uint32_t c2; /* how many bits to transfer on this iteration */ 1.91 - uint32_t d2; /* bits to transfer on this iteration */ 1.92 +#if (G4_DEBUG >= 2) 1.93 + { 1.94 + int i; 1.95 + fprintf (stderr, "%d %04x: ", count, bits); 1.96 + for (i = count - 1; i >= 0; i--) 1.97 + fprintf (stderr, "%d", (bits >> i) & 1); 1.98 + fprintf (stderr, "\n"); 1.99 + } 1.100 +#endif 1.101 1.102 - while (count) 1.103 + while (count > buf->bit_idx) 1.104 { 1.105 - b2 = 8 - buf->bit_idx; 1.106 - if (b2 >= count) 1.107 - c2 = count; 1.108 - else 1.109 - c2 = b2; 1.110 - d2 = bits >> (count - c2); 1.111 - buf->data [buf->byte_idx] |= (d2 << (b2 + c2)); 1.112 - buf->bit_idx += c2; 1.113 - if (buf->bit_idx > 7) 1.114 - advance_byte (buf); 1.115 - count -= c2; 1.116 + buf->data [buf->byte_idx] |= bits >> (count - buf->bit_idx); 1.117 + count -= buf->bit_idx; 1.118 + advance_byte (buf); 1.119 } 1.120 + 1.121 + bits &= ((1 << count) - 1); 1.122 + buf->data [buf->byte_idx] |= bits << (buf->bit_idx - count); 1.123 + buf->bit_idx -= count; 1.124 + if (buf->bit_idx == 0) 1.125 + advance_byte (buf); 1.126 } 1.127 1.128 1.129 @@ -169,17 +191,29 @@ 1.130 a0_c = 0; 1.131 1.132 a1 = g4_find_pixel (row, 0, width, 1); 1.133 + 1.134 b1 = g4_find_pixel (ref, 0, width, 1); 1.135 + 1.136 +#if G4_DEBUG 1.137 + fprintf (stderr, "start of row\n"); 1.138 + if ((a1 != width) || (b1 != width)) 1.139 + { 1.140 + fprintf (stderr, "a1 = %u, b1 = %u\n", a1, b1); 1.141 + } 1.142 +#endif 1.143 1.144 while (a0 < width) 1.145 { 1.146 - b2 = g4_find_pixel (ref, b1 + 1, width, g4_get_pixel (ref, b1)); 1.147 + b2 = g4_find_pixel (ref, b1 + 1, width, ! g4_get_pixel (ref, b1)); 1.148 1.149 if (b2 < a1) 1.150 { 1.151 /* pass mode - 0001 */ 1.152 write_bits (buf, 4, 0x1); 1.153 a0 = b2; 1.154 +#if G4_DEBUG 1.155 + fprintf (stderr, "pass\n"); 1.156 +#endif 1.157 } 1.158 else if (abs (a1 - b1) <= 3) 1.159 { 1.160 @@ -188,14 +222,22 @@ 1.161 g4_vert_code [3 + a1 - b1].count, 1.162 g4_vert_code [3 + a1 - b1].bits); 1.163 a0 = a1; 1.164 +#if G4_DEBUG 1.165 + fprintf (stderr, "vertical %d\n", a1 - b1); 1.166 +#endif 1.167 } 1.168 else 1.169 { 1.170 /* horizontal mode - 001 */ 1.171 - a2 = g4_find_pixel (row, a1, width, a0_c); 1.172 + a2 = g4_find_pixel (row, a1 + 1, width, a0_c); 1.173 write_bits (buf, 3, 0x1); 1.174 g4_encode_horizontal_run (buf, a0_c, a1 - a0); 1.175 g4_encode_horizontal_run (buf, ! a0_c, a2 - a1); 1.176 +#if G4_DEBUG 1.177 + fprintf (stderr, "horizontal %d %s, %d %s\n", 1.178 + a1 - a0, a0_c ? "black" : "white", 1.179 + a2 - a1, a0_c ? "white" : "black"); 1.180 +#endif 1.181 a0 = a2; 1.182 } 1.183 1.184 @@ -205,15 +247,19 @@ 1.185 a0_c = g4_get_pixel (row, a0); 1.186 1.187 a1 = g4_find_pixel (row, a0 + 1, width, ! a0_c); 1.188 - b1 = g4_find_pixel (ref, a0 + 1, width, a0_c); 1.189 - b1 = g4_find_pixel (ref, b1 + 1, width, ! a0_c); 1.190 + b1 = g4_find_pixel (ref, a0 + 1, width, ! g4_get_pixel (ref, a0)); 1.191 + if (g4_get_pixel (ref, b1) == a0_c) 1.192 + b1 = g4_find_pixel (ref, b1 + 1, width, ! a0_c); 1.193 +#if G4_DEBUG 1.194 + fprintf (stderr, "a1 = %u, b1 = %u\n", a1, b1); 1.195 +#endif 1.196 } 1.197 } 1.198 1.199 1.200 void bitblt_write_g4 (Bitmap *bitmap, FILE *f) 1.201 { 1.202 - uint32_t width = (bitmap->rect.max.x - bitmap->rect.min.x) + 1; 1.203 + uint32_t width = bitmap->rect.max.x - bitmap->rect.min.x; 1.204 uint32_t row; 1.205 struct bit_buffer bb; 1.206 1.207 @@ -222,13 +268,17 @@ 1.208 word_type *cur_line; 1.209 word_type *ref_line; /* reference (previous) row */ 1.210 1.211 +#if G4_DEBUG 1.212 + fprintf (stderr, "width %u\n", width); 1.213 +#endif 1.214 + 1.215 temp_buffer = pdf_calloc ((width + BITS_PER_WORD - 1) / BITS_PER_WORD, 1.216 sizeof (word_type)); 1.217 1.218 cur_line = bitmap->bits; 1.219 ref_line = temp_buffer; 1.220 1.221 - memset (& bb, 0, sizeof (bb)); 1.222 + init_bit_buffer (& bb); 1.223 1.224 bb.f = f; 1.225