git.sesse.net Git - fjl/blob - driver.c

   1 #include <stdio.h>
   2 #include <string.h>
   3 #include <stdlib.h>
   4
   5 #include "bytesource.h"
   6 #include "choice.h"
   7 #include "dehuff.h"
   8 #include "idct.h"
   9 #include "input.h"
  10 #include "zigzag.h"
  11
  12 struct jpeg_image {
  13         unsigned precision;
  14         unsigned width, height;
  15         unsigned num_components;
  16         unsigned hsample[256], vsample[256], qtable[256];
  17         unsigned max_hsample, max_vsample;
  18         unsigned stride[256];
  19         unsigned num_blocks_horizontal, num_blocks_vertical;
  20         uint32_t qvalues[256][DCTSIZE2];
  21         void* idct_data[256];
  22         uint8_t* pixel_data[256];
  23         uint8_t* pixel_write_pointer[256];
  24 };
  25
  26 ssize_t stdio_read(void* userdata, uint8_t* buf, size_t count)
  27 {
  28         return fread(buf, 1, count, (FILE*)userdata);
  29 }
  30
  31 void read_dqt(struct byte_source* source, struct jpeg_image* image)
  32 {
  33         unsigned len = read_uint16(byte_source_input_func, source);
  34         assert(len >= 67);
  35         uint8_t precision_table = read_uint8(byte_source_input_func, source);
  36         int precision = precision_table >> 4;  // 0 = 8 bits, otherwise 16 bits.
  37         int table = precision_table & 0x0f;
  38
  39         if (image->idct_data[table] != NULL) {
  40                 idct_choice_free(image->idct_data[table]);
  41         }
  42
  43         if (precision != 0) {
  44                 assert(len == 131);
  45                 fprintf(stderr, "Quantization table %u: 16 bits/entry\n", table);
  46         } else {
  47                 assert(len == 67);
  48                 fprintf(stderr, "Quantization table %u: 8 bits/entry\n", table);
  49         }
  50
  51         for (unsigned i = 0; i < 64; ++i) {
  52                 if (precision != 0) {
  53                         image->qvalues[table][unzigzag[i]] =
  54                                 read_uint16(byte_source_input_func, source);
  55                 } else {
  56                         image->qvalues[table][unzigzag[i]] =
  57                                 read_uint8(byte_source_input_func, source);
  58                 }
  59         }
  60
  61         image->idct_data[table] = idct_choice_alloc(image->qvalues[table]);
  62 }
  63
  64 void read_sof(struct byte_source* source, struct jpeg_image* image)
  65 {
  66         unsigned len = read_uint16(byte_source_input_func, source);
  67         assert(len >= 8);
  68         image->precision = read_uint8(byte_source_input_func, source);
  69         assert(image->precision == 8);
  70         image->height = read_uint16(byte_source_input_func, source);
  71         image->width = read_uint16(byte_source_input_func, source);
  72         image->num_components = read_uint8(byte_source_input_func, source);
  73         len -= 8;
  74
  75         fprintf(stderr, "%u-bit %ux%u JPEG with %u components\n",
  76                 image->precision, image->width, image->height, image->num_components);
  77
  78         for (unsigned i = 0; i < image->num_components; ++i) {
  79                 assert(len >= 3);
  80                 unsigned c = read_uint8(byte_source_input_func, source);
  81                 unsigned sampling_factors = read_uint8(byte_source_input_func, source);
  82                 image->hsample[c] = sampling_factors >> 4;
  83                 image->vsample[c] = sampling_factors & 0x0f;
  84                 image->qtable[c] = read_uint8(byte_source_input_func, source);
  85                 len -= 3;
  86
  87                 if (image->hsample[c] > image->max_hsample) {
  88                         image->max_hsample = image->hsample[c];
  89                 }
  90                 if (image->vsample[c] > image->max_vsample) {
  91                         image->max_vsample = image->vsample[c];
  92                 }
  93
  94                 fprintf(stderr, "Component %u: sampling factors %u x %x, quantization table %u\n",
  95                         c, image->hsample[c], image->vsample[c], image->qtable[c]);
  96         }
  97
  98         image->num_blocks_horizontal = (image->width + image->max_hsample * DCTSIZE - 1) / (image->max_hsample * DCTSIZE);
  99         image->num_blocks_vertical = (image->height + image->max_vsample * DCTSIZE - 1) / (image->max_vsample * DCTSIZE);
 100
 101         for (unsigned c = 0; c < 256; ++c) {
 102                 if (image->hsample[c] == 0) {
 103                         continue;
 104                 }
 105
 106                 unsigned width = image->num_blocks_horizontal * image->hsample[c] * DCTSIZE;
 107                 unsigned height = image->num_blocks_vertical * image->vsample[c] * DCTSIZE;
 108                 image->stride[c] = width;
 109                 image->pixel_data[c] = (uint8_t*)malloc(width * height);
 110                 assert(image->pixel_data[c] != NULL);
 111                 image->pixel_write_pointer[c] = image->pixel_data[c];
 112
 113                 fprintf(stderr, "Component %u: allocating %d x %d\n", c, width, height);
 114         }
 115 }
 116
 117 void decode_ac_coefficients(const struct huffman_table* tbl, struct bit_source* bits, int16_t* coeff)
 118 {
 119         for (unsigned i = 0; i < DCTSIZE2 - 1; ) {
 120                 possibly_refill(bits, DEHUF_AC_TABLE_BITS);
 121                 unsigned lookup = peek_bits(bits, DEHUF_AC_TABLE_BITS);
 122                 int code = tbl->ac_table_codes[lookup];
 123
 124                 if (__builtin_expect(code == AC_DEHUF_SLOW_PATH, 0)) {
 125                         unsigned rs = read_huffman_symbol_no_refill(tbl, bits);
 126                         unsigned r = rs >> 4;
 127                         unsigned s = rs & 0xf;
 128                         i += r + 1;
 129                         possibly_refill(bits, s);
 130
 131                         if (rs == 0x00) {
 132                                 assert(code == AC_DEHUF_SLOW_PATH || code == AC_END_OF_BLOCK);
 133                                 /* end of block */
 134                                 break;
 135                         }
 136                         if (rs == 0xf0) {
 137                                 assert(code == AC_DEHUF_SLOW_PATH || code == AC_SIXTEEN_ZEROS);
 138                                 /* 16 zero coefficients */
 139                                 continue;
 140                         }
 141
 142                         coeff[unzigzag[i]] = extend(read_bits(bits, s), s);
 143                 } else {
 144                         unsigned length = tbl->ac_table_length[lookup];
 145                         int r = tbl->ac_table_skip[lookup];
 146                         assert(r >= 1);
 147                         i += r;
 148                         assert(bits->bits_available >= length);
 149                         read_bits(bits, length);
 150                         if (code == AC_END_OF_BLOCK) {
 151                                 break;
 152                         }
 153                         if (code == AC_SIXTEEN_ZEROS) {
 154                                 continue;
 155                         }
 156                         coeff[unzigzag[i]] = code;
 157                 }
 158         }
 159 }
 160
 161 void read_scan(struct byte_source* source, struct jpeg_image* image, huffman_tables_t* tables)
 162 {
 163         unsigned len = read_uint16(byte_source_input_func, source);
 164         assert(len >= 2);
 165         len -= 2;
 166
 167         assert(len >= 1);
 168         unsigned num_components = read_uint8(byte_source_input_func, source);
 169         --len;
 170
 171         unsigned component_num[256];
 172         unsigned dc_huffman_table[256], ac_huffman_table[256];
 173         unsigned ss, se, ah_al;
 174         int last_dc[256];
 175
 176         for (unsigned i = 0; i < num_components; ++i) {
 177                 unsigned char td_ta;
 178                 assert(len >= 2);
 179                 component_num[i] = read_uint8(byte_source_input_func, source);
 180                 td_ta = read_uint8(byte_source_input_func, source);
 181                 len -= 2;
 182                 dc_huffman_table[i] = td_ta >> 4;
 183                 ac_huffman_table[i] = td_ta & 0x0f;
 184                 last_dc[i] = 0;
 185         }
 186
 187         assert(len >= 3);
 188         ss = read_uint8(byte_source_input_func, source);
 189         se = read_uint8(byte_source_input_func, source);
 190         ah_al = read_uint8(byte_source_input_func, source);
 191         len -= 3;
 192
 193         if (len != 0) {
 194                 fprintf(stderr, "Error: %u unused bytes at end of SOS segment\n", len);
 195         }
 196
 197         struct bit_source bits;
 198         init_bit_source(&bits, byte_source_input_func, 8, source);
 199
 200         unsigned mcu_x = 0, mcu_y = 0;
 201
 202         while (!bits.source_eof) {
 203                 for (unsigned c = 0; c < num_components; ++c) {
 204                         unsigned cn = component_num[c];
 205                         assert(image->idct_data[image->qtable[cn]] != NULL);
 206
 207                         uint8_t* pixel_write_pointer_y = image->pixel_write_pointer[cn];
 208                         for (unsigned local_yb = 0; local_yb < image->vsample[cn]; ++local_yb, pixel_write_pointer_y += image->stride[cn] * DCTSIZE) {
 209                                 uint8_t* pixel_write_pointer = pixel_write_pointer_y;
 210                                 for (unsigned local_xb = 0; local_xb < image->hsample[cn]; ++local_xb, pixel_write_pointer += DCTSIZE) {
 211                                         const struct huffman_table* dc_table = &((*tables)[DC_CLASS][dc_huffman_table[c]]);
 212                                         const struct huffman_table* ac_table = &((*tables)[AC_CLASS][ac_huffman_table[c]]);
 213
 214                                         // decode DC component
 215                                         unsigned dc_category = read_huffman_symbol(dc_table, &bits);
 216                                         possibly_refill(&bits, dc_category);
 217                                         last_dc[c] += extend(read_bits(&bits, dc_category), dc_category);
 218
 219                                         int16_t coeff[DCTSIZE2] = { 0 };
 220                                         coeff[0] = last_dc[c];
 221                                         decode_ac_coefficients(ac_table, &bits, coeff);
 222
 223                                         uint8_t pixdata[DCTSIZE2];
 224                                         idct_choice(coeff, image->idct_data[image->qtable[cn]], pixdata);
 225
 226                                         uint8_t* dest_pixdata = pixel_write_pointer;
 227                                         for (unsigned y = 0; y < DCTSIZE; ++y, dest_pixdata += image->stride[cn]) {
 228                                                 memcpy(dest_pixdata, pixdata + y * DCTSIZE, DCTSIZE);
 229                                         }
 230                                 }
 231                         }
 232                         image->pixel_write_pointer[cn] += DCTSIZE * image->hsample[cn];
 233                 }
 234
 235                 if (++mcu_x == image->num_blocks_horizontal) {
 236                         ++mcu_y;
 237                         mcu_x = 0;
 238
 239                         for (unsigned c = 0; c < num_components; ++c) {
 240                                 unsigned cn = component_num[c];
 241                                 image->pixel_write_pointer[cn] += (image->vsample[cn] * DCTSIZE - 1) * image->stride[cn];
 242                         }
 243
 244                         // Some debug code.
 245                         const int c = 1;
 246                         if (mcu_y == image->num_blocks_vertical) {
 247                                 unsigned stride = image->num_blocks_horizontal * image->hsample[c] * DCTSIZE;
 248                                 unsigned height = image->num_blocks_vertical * image->vsample[c] * DCTSIZE;
 249                                 printf("P5\n%u %u\n255\n", stride, height);
 250                                 fwrite(image->pixel_data[c], stride * height, 1, stdout);
 251                         }
 252                 }
 253         }
 254         if (len != 0) {
 255                 fprintf(stderr, "Error: %u unused bytes at end of SOS segment\n", len);
 256         }
 257 }
 258
 259 void skip_segment(struct byte_source* source)
 260 {
 261         uint8_t buf[4096];
 262         for ( ;; ) {
 263                 ssize_t ret = byte_source_input_func(source, buf, 4096);
 264                 if (ret == -1) {
 265                         fprintf(stderr, "Input error!\n");
 266                         exit(1);
 267                 }
 268                 if (ret == 0) {
 269                         return;
 270                 }
 271         }
 272 }
 273
 274 int main(void)
 275 {
 276         struct jpeg_image jpeg;
 277         memset(&jpeg, 0, sizeof(jpeg));
 278         init_choices();
 279
 280         struct byte_source source;
 281         init_byte_source(&source, stdio_read, stdin);
 282
 283         huffman_tables_t tables;
 284
 285         for ( ;; ) {
 286                 uint8_t m2 = byte_source_read_marker(&source);
 287                 assert(m2 != 0x00);
 288
 289                 fprintf(stderr, "Marker 0x%02x, at position %ld\n", m2, ftell(stdin) - source.bytes_available);
 290
 291                 switch (m2) {
 292                 case 0xe0:
 293                 case 0xe1:
 294                 case 0xe2:
 295                 case 0xe3:
 296                 case 0xe4:
 297                 case 0xe5:
 298                 case 0xe6:
 299                 case 0xe7:
 300                 case 0xe8:
 301                 case 0xe9:
 302                 case 0xea:
 303                 case 0xeb:
 304                 case 0xec:
 305                 case 0xed:
 306                 case 0xee:
 307                 case 0xef:
 308                         /* APP0 through APPF */
 309                 case 0xfc:
 310                         /* some EXIF stuff */
 311                 case 0xfe:
 312                         /* comment */
 313                 case 0xff:
 314                         /* ignore */
 315                         skip_segment(&source);
 316                         break;
 317                 case 0xdb:
 318                         /* DQT */
 319                         read_dqt(&source, &jpeg);
 320                         break;
 321                 case 0xc0:
 322                         /* SOF0 (baseline DCT, Huffman encoded) */
 323                         read_sof(&source, &jpeg);
 324                         break;
 325                 case 0xd8:
 326                         /* SOI */
 327                         break;
 328                 case 0xd9:
 329                         /* EOI */
 330                         exit(0);
 331                 case 0xc4:
 332                         /* DHT (define Huffman tables) */
 333                         read_huffman_tables(&tables, byte_source_input_func, &source);
 334                         break;
 335                 case 0xda:
 336                         /* SOS (start of scan) */
 337                         read_scan(&source, &jpeg, &tables);
 338                         break;
 339                 default:
 340                         fprintf(stderr, "Error: Unknown marker 0x%02x\n", m2);
 341                         exit(1);
 342                 }
 343         }
 344 }