media/libjpeg/jcmarker.c

   1 /*
   2  * jcmarker.c
   3  *
   4  * This file was part of the Independent JPEG Group's software:
   5  * Copyright (C) 1991-1998, Thomas G. Lane.
   6  * Modifications:
   7  * Copyright (C) 2010, D. R. Commander.
   8  * For conditions of distribution and use, see the accompanying README file.
   9  *
  10  * This file contains routines to write JPEG datastream markers.
  11  */
  12
  13 #define JPEG_INTERNALS
  14 #include "jinclude.h"
  15 #include "jpeglib.h"
  16 #include "jpegcomp.h"
  17
  18
  19 typedef enum {                  /* JPEG marker codes */
  20   M_SOF0  = 0xc0,
  21   M_SOF1  = 0xc1,
  22   M_SOF2  = 0xc2,
  23   M_SOF3  = 0xc3,
  24
  25   M_SOF5  = 0xc5,
  26   M_SOF6  = 0xc6,
  27   M_SOF7  = 0xc7,
  28
  29   M_JPG   = 0xc8,
  30   M_SOF9  = 0xc9,
  31   M_SOF10 = 0xca,
  32   M_SOF11 = 0xcb,
  33
  34   M_SOF13 = 0xcd,
  35   M_SOF14 = 0xce,
  36   M_SOF15 = 0xcf,
  37
  38   M_DHT   = 0xc4,
  39
  40   M_DAC   = 0xcc,
  41
  42   M_RST0  = 0xd0,
  43   M_RST1  = 0xd1,
  44   M_RST2  = 0xd2,
  45   M_RST3  = 0xd3,
  46   M_RST4  = 0xd4,
  47   M_RST5  = 0xd5,
  48   M_RST6  = 0xd6,
  49   M_RST7  = 0xd7,
  50
  51   M_SOI   = 0xd8,
  52   M_EOI   = 0xd9,
  53   M_SOS   = 0xda,
  54   M_DQT   = 0xdb,
  55   M_DNL   = 0xdc,
  56   M_DRI   = 0xdd,
  57   M_DHP   = 0xde,
  58   M_EXP   = 0xdf,
  59
  60   M_APP0  = 0xe0,
  61   M_APP1  = 0xe1,
  62   M_APP2  = 0xe2,
  63   M_APP3  = 0xe3,
  64   M_APP4  = 0xe4,
  65   M_APP5  = 0xe5,
  66   M_APP6  = 0xe6,
  67   M_APP7  = 0xe7,
  68   M_APP8  = 0xe8,
  69   M_APP9  = 0xe9,
  70   M_APP10 = 0xea,
  71   M_APP11 = 0xeb,
  72   M_APP12 = 0xec,
  73   M_APP13 = 0xed,
  74   M_APP14 = 0xee,
  75   M_APP15 = 0xef,
  76
  77   M_JPG0  = 0xf0,
  78   M_JPG13 = 0xfd,
  79   M_COM   = 0xfe,
  80
  81   M_TEM   = 0x01,
  82
  83   M_ERROR = 0x100
  84 } JPEG_MARKER;
  85
  86
  87 /* Private state */
  88
  89 typedef struct {
  90   struct jpeg_marker_writer pub; /* public fields */
  91
  92   unsigned int last_restart_interval; /* last DRI value emitted; 0 after SOI */
  93 } my_marker_writer;
  94
  95 typedef my_marker_writer * my_marker_ptr;
  96
  97
  98 /*
  99  * Basic output routines.
 100  *
 101  * Note that we do not support suspension while writing a marker.
 102  * Therefore, an application using suspension must ensure that there is
 103  * enough buffer space for the initial markers (typ. 600-700 bytes) before
 104  * calling jpeg_start_compress, and enough space to write the trailing EOI
 105  * (a few bytes) before calling jpeg_finish_compress.  Multipass compression
 106  * modes are not supported at all with suspension, so those two are the only
 107  * points where markers will be written.
 108  */
 109
 110 LOCAL(void)
 111 emit_byte (j_compress_ptr cinfo, int val)
 112 /* Emit a byte */
 113 {
 114   struct jpeg_destination_mgr * dest = cinfo->dest;
 115
 116   *(dest->next_output_byte)++ = (JOCTET) val;
 117   if (--dest->free_in_buffer == 0) {
 118     if (! (*dest->empty_output_buffer) (cinfo))
 119       ERREXIT(cinfo, JERR_CANT_SUSPEND);
 120   }
 121 }
 122
 123
 124 LOCAL(void)
 125 emit_marker (j_compress_ptr cinfo, JPEG_MARKER mark)
 126 /* Emit a marker code */
 127 {
 128   emit_byte(cinfo, 0xFF);
 129   emit_byte(cinfo, (int) mark);
 130 }
 131
 132
 133 LOCAL(void)
 134 emit_2bytes (j_compress_ptr cinfo, int value)
 135 /* Emit a 2-byte integer; these are always MSB first in JPEG files */
 136 {
 137   emit_byte(cinfo, (value >> 8) & 0xFF);
 138   emit_byte(cinfo, value & 0xFF);
 139 }
 140
 141
 142 /*
 143  * Routines to write specific marker types.
 144  */
 145
 146 LOCAL(int)
 147 emit_dqt (j_compress_ptr cinfo, int index)
 148 /* Emit a DQT marker */
 149 /* Returns the precision used (0 = 8bits, 1 = 16bits) for baseline checking */
 150 {
 151   JQUANT_TBL * qtbl = cinfo->quant_tbl_ptrs[index];
 152   int prec;
 153   int i;
 154
 155   if (qtbl == NULL)
 156     ERREXIT1(cinfo, JERR_NO_QUANT_TABLE, index);
 157
 158   prec = 0;
 159   for (i = 0; i < DCTSIZE2; i++) {
 160     if (qtbl->quantval[i] > 255)
 161       prec = 1;
 162   }
 163
 164   if (! qtbl->sent_table) {
 165     emit_marker(cinfo, M_DQT);
 166
 167     emit_2bytes(cinfo, prec ? DCTSIZE2*2 + 1 + 2 : DCTSIZE2 + 1 + 2);
 168
 169     emit_byte(cinfo, index + (prec<<4));
 170
 171     for (i = 0; i < DCTSIZE2; i++) {
 172       /* The table entries must be emitted in zigzag order. */
 173       unsigned int qval = qtbl->quantval[jpeg_natural_order[i]];
 174       if (prec)
 175         emit_byte(cinfo, (int) (qval >> 8));
 176       emit_byte(cinfo, (int) (qval & 0xFF));
 177     }
 178
 179     qtbl->sent_table = TRUE;
 180   }
 181
 182   return prec;
 183 }
 184
 185
 186 LOCAL(void)
 187 emit_dht (j_compress_ptr cinfo, int index, boolean is_ac)
 188 /* Emit a DHT marker */
 189 {
 190   JHUFF_TBL * htbl;
 191   int length, i;
 192
 193   if (is_ac) {
 194     htbl = cinfo->ac_huff_tbl_ptrs[index];
 195     index += 0x10;              /* output index has AC bit set */
 196   } else {
 197     htbl = cinfo->dc_huff_tbl_ptrs[index];
 198   }
 199
 200   if (htbl == NULL)
 201     ERREXIT1(cinfo, JERR_NO_HUFF_TABLE, index);
 202
 203   if (! htbl->sent_table) {
 204     emit_marker(cinfo, M_DHT);
 205
 206     length = 0;
 207     for (i = 1; i <= 16; i++)
 208       length += htbl->bits[i];
 209
 210     emit_2bytes(cinfo, length + 2 + 1 + 16);
 211     emit_byte(cinfo, index);
 212
 213     for (i = 1; i <= 16; i++)
 214       emit_byte(cinfo, htbl->bits[i]);
 215
 216     for (i = 0; i < length; i++)
 217       emit_byte(cinfo, htbl->huffval[i]);
 218
 219     htbl->sent_table = TRUE;
 220   }
 221 }
 222
 223
 224 LOCAL(void)
 225 emit_dac (j_compress_ptr cinfo)
 226 /* Emit a DAC marker */
 227 /* Since the useful info is so small, we want to emit all the tables in */
 228 /* one DAC marker.  Therefore this routine does its own scan of the table. */
 229 {
 230 #ifdef C_ARITH_CODING_SUPPORTED
 231   char dc_in_use[NUM_ARITH_TBLS];
 232   char ac_in_use[NUM_ARITH_TBLS];
 233   int length, i;
 234   jpeg_component_info *compptr;
 235
 236   for (i = 0; i < NUM_ARITH_TBLS; i++)
 237     dc_in_use[i] = ac_in_use[i] = 0;
 238
 239   for (i = 0; i < cinfo->comps_in_scan; i++) {
 240     compptr = cinfo->cur_comp_info[i];
 241     dc_in_use[compptr->dc_tbl_no] = 1;
 242     ac_in_use[compptr->ac_tbl_no] = 1;
 243   }
 244
 245   length = 0;
 246   for (i = 0; i < NUM_ARITH_TBLS; i++)
 247     length += dc_in_use[i] + ac_in_use[i];
 248
 249   emit_marker(cinfo, M_DAC);
 250
 251   emit_2bytes(cinfo, length*2 + 2);
 252
 253   for (i = 0; i < NUM_ARITH_TBLS; i++) {
 254     if (dc_in_use[i]) {
 255       emit_byte(cinfo, i);
 256       emit_byte(cinfo, cinfo->arith_dc_L[i] + (cinfo->arith_dc_U[i]<<4));
 257     }
 258     if (ac_in_use[i]) {
 259       emit_byte(cinfo, i + 0x10);
 260       emit_byte(cinfo, cinfo->arith_ac_K[i]);
 261     }
 262   }
 263 #endif /* C_ARITH_CODING_SUPPORTED */
 264 }
 265
 266
 267 LOCAL(void)
 268 emit_dri (j_compress_ptr cinfo)
 269 /* Emit a DRI marker */
 270 {
 271   emit_marker(cinfo, M_DRI);
 272
 273   emit_2bytes(cinfo, 4);        /* fixed length */
 274
 275   emit_2bytes(cinfo, (int) cinfo->restart_interval);
 276 }
 277
 278
 279 LOCAL(void)
 280 emit_sof (j_compress_ptr cinfo, JPEG_MARKER code)
 281 /* Emit a SOF marker */
 282 {
 283   int ci;
 284   jpeg_component_info *compptr;
 285
 286   emit_marker(cinfo, code);
 287
 288   emit_2bytes(cinfo, 3 * cinfo->num_components + 2 + 5 + 1); /* length */
 289
 290   /* Make sure image isn't bigger than SOF field can handle */
 291   if ((long) cinfo->_jpeg_height > 65535L ||
 292       (long) cinfo->_jpeg_width > 65535L)
 293     ERREXIT1(cinfo, JERR_IMAGE_TOO_BIG, (unsigned int) 65535);
 294
 295   emit_byte(cinfo, cinfo->data_precision);
 296   emit_2bytes(cinfo, (int) cinfo->_jpeg_height);
 297   emit_2bytes(cinfo, (int) cinfo->_jpeg_width);
 298
 299   emit_byte(cinfo, cinfo->num_components);
 300
 301   for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
 302        ci++, compptr++) {
 303     emit_byte(cinfo, compptr->component_id);
 304     emit_byte(cinfo, (compptr->h_samp_factor << 4) + compptr->v_samp_factor);
 305     emit_byte(cinfo, compptr->quant_tbl_no);
 306   }
 307 }
 308
 309
 310 LOCAL(void)
 311 emit_sos (j_compress_ptr cinfo)
 312 /* Emit a SOS marker */
 313 {
 314   int i, td, ta;
 315   jpeg_component_info *compptr;
 316
 317   emit_marker(cinfo, M_SOS);
 318
 319   emit_2bytes(cinfo, 2 * cinfo->comps_in_scan + 2 + 1 + 3); /* length */
 320
 321   emit_byte(cinfo, cinfo->comps_in_scan);
 322
 323   for (i = 0; i < cinfo->comps_in_scan; i++) {
 324     compptr = cinfo->cur_comp_info[i];
 325     emit_byte(cinfo, compptr->component_id);
 326     td = compptr->dc_tbl_no;
 327     ta = compptr->ac_tbl_no;
 328     if (cinfo->progressive_mode) {
 329       /* Progressive mode: only DC or only AC tables are used in one scan;
 330        * furthermore, Huffman coding of DC refinement uses no table at all.
 331        * We emit 0 for unused field(s); this is recommended by the P&M text
 332        * but does not seem to be specified in the standard.
 333        */
 334       if (cinfo->Ss == 0) {
 335         ta = 0;                 /* DC scan */
 336         if (cinfo->Ah != 0 && !cinfo->arith_code)
 337           td = 0;               /* no DC table either */
 338       } else {
 339         td = 0;                 /* AC scan */
 340       }
 341     }
 342     emit_byte(cinfo, (td << 4) + ta);
 343   }
 344
 345   emit_byte(cinfo, cinfo->Ss);
 346   emit_byte(cinfo, cinfo->Se);
 347   emit_byte(cinfo, (cinfo->Ah << 4) + cinfo->Al);
 348 }
 349
 350
 351 LOCAL(void)
 352 emit_jfif_app0 (j_compress_ptr cinfo)
 353 /* Emit a JFIF-compliant APP0 marker */
 354 {
 355   /*
 356    * Length of APP0 block       (2 bytes)
 357    * Block ID                   (4 bytes - ASCII "JFIF")
 358    * Zero byte                  (1 byte to terminate the ID string)
 359    * Version Major, Minor       (2 bytes - major first)
 360    * Units                      (1 byte - 0x00 = none, 0x01 = inch, 0x02 = cm)
 361    * Xdpu                       (2 bytes - dots per unit horizontal)
 362    * Ydpu                       (2 bytes - dots per unit vertical)
 363    * Thumbnail X size           (1 byte)
 364    * Thumbnail Y size           (1 byte)
 365    */
 366
 367   emit_marker(cinfo, M_APP0);
 368
 369   emit_2bytes(cinfo, 2 + 4 + 1 + 2 + 1 + 2 + 2 + 1 + 1); /* length */
 370
 371   emit_byte(cinfo, 0x4A);       /* Identifier: ASCII "JFIF" */
 372   emit_byte(cinfo, 0x46);
 373   emit_byte(cinfo, 0x49);
 374   emit_byte(cinfo, 0x46);
 375   emit_byte(cinfo, 0);
 376   emit_byte(cinfo, cinfo->JFIF_major_version); /* Version fields */
 377   emit_byte(cinfo, cinfo->JFIF_minor_version);
 378   emit_byte(cinfo, cinfo->density_unit); /* Pixel size information */
 379   emit_2bytes(cinfo, (int) cinfo->X_density);
 380   emit_2bytes(cinfo, (int) cinfo->Y_density);
 381   emit_byte(cinfo, 0);          /* No thumbnail image */
 382   emit_byte(cinfo, 0);
 383 }
 384
 385
 386 LOCAL(void)
 387 emit_adobe_app14 (j_compress_ptr cinfo)
 388 /* Emit an Adobe APP14 marker */
 389 {
 390   /*
 391    * Length of APP14 block      (2 bytes)
 392    * Block ID                   (5 bytes - ASCII "Adobe")
 393    * Version Number             (2 bytes - currently 100)
 394    * Flags0                     (2 bytes - currently 0)
 395    * Flags1                     (2 bytes - currently 0)
 396    * Color transform            (1 byte)
 397    *
 398    * Although Adobe TN 5116 mentions Version = 101, all the Adobe files
 399    * now in circulation seem to use Version = 100, so that's what we write.
 400    *
 401    * We write the color transform byte as 1 if the JPEG color space is
 402    * YCbCr, 2 if it's YCCK, 0 otherwise.  Adobe's definition has to do with
 403    * whether the encoder performed a transformation, which is pretty useless.
 404    */
 405
 406   emit_marker(cinfo, M_APP14);
 407
 408   emit_2bytes(cinfo, 2 + 5 + 2 + 2 + 2 + 1); /* length */
 409
 410   emit_byte(cinfo, 0x41);       /* Identifier: ASCII "Adobe" */
 411   emit_byte(cinfo, 0x64);
 412   emit_byte(cinfo, 0x6F);
 413   emit_byte(cinfo, 0x62);
 414   emit_byte(cinfo, 0x65);
 415   emit_2bytes(cinfo, 100);      /* Version */
 416   emit_2bytes(cinfo, 0);        /* Flags0 */
 417   emit_2bytes(cinfo, 0);        /* Flags1 */
 418   switch (cinfo->jpeg_color_space) {
 419   case JCS_YCbCr:
 420     emit_byte(cinfo, 1);        /* Color transform = 1 */
 421     break;
 422   case JCS_YCCK:
 423     emit_byte(cinfo, 2);        /* Color transform = 2 */
 424     break;
 425   default:
 426     emit_byte(cinfo, 0);        /* Color transform = 0 */
 427     break;
 428   }
 429 }
 430
 431
 432 /*
 433  * These routines allow writing an arbitrary marker with parameters.
 434  * The only intended use is to emit COM or APPn markers after calling
 435  * write_file_header and before calling write_frame_header.
 436  * Other uses are not guaranteed to produce desirable results.
 437  * Counting the parameter bytes properly is the caller's responsibility.
 438  */
 439
 440 METHODDEF(void)
 441 write_marker_header (j_compress_ptr cinfo, int marker, unsigned int datalen)
 442 /* Emit an arbitrary marker header */
 443 {
 444   if (datalen > (unsigned int) 65533)           /* safety check */
 445     ERREXIT(cinfo, JERR_BAD_LENGTH);
 446
 447   emit_marker(cinfo, (JPEG_MARKER) marker);
 448
 449   emit_2bytes(cinfo, (int) (datalen + 2));      /* total length */
 450 }
 451
 452 METHODDEF(void)
 453 write_marker_byte (j_compress_ptr cinfo, int val)
 454 /* Emit one byte of marker parameters following write_marker_header */
 455 {
 456   emit_byte(cinfo, val);
 457 }
 458
 459
 460 /*
 461  * Write datastream header.
 462  * This consists of an SOI and optional APPn markers.
 463  * We recommend use of the JFIF marker, but not the Adobe marker,
 464  * when using YCbCr or grayscale data.  The JFIF marker should NOT
 465  * be used for any other JPEG colorspace.  The Adobe marker is helpful
 466  * to distinguish RGB, CMYK, and YCCK colorspaces.
 467  * Note that an application can write additional header markers after
 468  * jpeg_start_compress returns.
 469  */
 470
 471 METHODDEF(void)
 472 write_file_header (j_compress_ptr cinfo)
 473 {
 474   my_marker_ptr marker = (my_marker_ptr) cinfo->marker;
 475
 476   emit_marker(cinfo, M_SOI);    /* first the SOI */
 477
 478   /* SOI is defined to reset restart interval to 0 */
 479   marker->last_restart_interval = 0;
 480
 481   if (cinfo->write_JFIF_header) /* next an optional JFIF APP0 */
 482     emit_jfif_app0(cinfo);
 483   if (cinfo->write_Adobe_marker) /* next an optional Adobe APP14 */
 484     emit_adobe_app14(cinfo);
 485 }
 486
 487
 488 /*
 489  * Write frame header.
 490  * This consists of DQT and SOFn markers.
 491  * Note that we do not emit the SOF until we have emitted the DQT(s).
 492  * This avoids compatibility problems with incorrect implementations that
 493  * try to error-check the quant table numbers as soon as they see the SOF.
 494  */
 495
 496 METHODDEF(void)
 497 write_frame_header (j_compress_ptr cinfo)
 498 {
 499   int ci, prec;
 500   boolean is_baseline;
 501   jpeg_component_info *compptr;
 502
 503   /* Emit DQT for each quantization table.
 504    * Note that emit_dqt() suppresses any duplicate tables.
 505    */
 506   prec = 0;
 507   for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
 508        ci++, compptr++) {
 509     prec += emit_dqt(cinfo, compptr->quant_tbl_no);
 510   }
 511   /* now prec is nonzero iff there are any 16-bit quant tables. */
 512
 513   /* Check for a non-baseline specification.
 514    * Note we assume that Huffman table numbers won't be changed later.
 515    */
 516   if (cinfo->arith_code || cinfo->progressive_mode ||
 517       cinfo->data_precision != 8) {
 518     is_baseline = FALSE;
 519   } else {
 520     is_baseline = TRUE;
 521     for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
 522          ci++, compptr++) {
 523       if (compptr->dc_tbl_no > 1 || compptr->ac_tbl_no > 1)
 524         is_baseline = FALSE;
 525     }
 526     if (prec && is_baseline) {
 527       is_baseline = FALSE;
 528       /* If it's baseline except for quantizer size, warn the user */
 529       TRACEMS(cinfo, 0, JTRC_16BIT_TABLES);
 530     }
 531   }
 532
 533   /* Emit the proper SOF marker */
 534   if (cinfo->arith_code) {
 535     emit_sof(cinfo, M_SOF9);    /* SOF code for arithmetic coding */
 536   } else {
 537     if (cinfo->progressive_mode)
 538       emit_sof(cinfo, M_SOF2);  /* SOF code for progressive Huffman */
 539     else if (is_baseline)
 540       emit_sof(cinfo, M_SOF0);  /* SOF code for baseline implementation */
 541     else
 542       emit_sof(cinfo, M_SOF1);  /* SOF code for non-baseline Huffman file */
 543   }
 544 }
 545
 546
 547 /*
 548  * Write scan header.
 549  * This consists of DHT or DAC markers, optional DRI, and SOS.
 550  * Compressed data will be written following the SOS.
 551  */
 552
 553 METHODDEF(void)
 554 write_scan_header (j_compress_ptr cinfo)
 555 {
 556   my_marker_ptr marker = (my_marker_ptr) cinfo->marker;
 557   int i;
 558   jpeg_component_info *compptr;
 559
 560   if (cinfo->arith_code) {
 561     /* Emit arith conditioning info.  We may have some duplication
 562      * if the file has multiple scans, but it's so small it's hardly
 563      * worth worrying about.
 564      */
 565     emit_dac(cinfo);
 566   } else {
 567     /* Emit Huffman tables.
 568      * Note that emit_dht() suppresses any duplicate tables.
 569      */
 570     for (i = 0; i < cinfo->comps_in_scan; i++) {
 571       compptr = cinfo->cur_comp_info[i];
 572       if (cinfo->progressive_mode) {
 573         /* Progressive mode: only DC or only AC tables are used in one scan */
 574         if (cinfo->Ss == 0) {
 575           if (cinfo->Ah == 0)   /* DC needs no table for refinement scan */
 576             emit_dht(cinfo, compptr->dc_tbl_no, FALSE);
 577         } else {
 578           emit_dht(cinfo, compptr->ac_tbl_no, TRUE);
 579         }
 580       } else {
 581         /* Sequential mode: need both DC and AC tables */
 582         emit_dht(cinfo, compptr->dc_tbl_no, FALSE);
 583         emit_dht(cinfo, compptr->ac_tbl_no, TRUE);
 584       }
 585     }
 586   }
 587
 588   /* Emit DRI if required --- note that DRI value could change for each scan.
 589    * We avoid wasting space with unnecessary DRIs, however.
 590    */
 591   if (cinfo->restart_interval != marker->last_restart_interval) {
 592     emit_dri(cinfo);
 593     marker->last_restart_interval = cinfo->restart_interval;
 594   }
 595
 596   emit_sos(cinfo);
 597 }
 598
 599
 600 /*
 601  * Write datastream trailer.
 602  */
 603
 604 METHODDEF(void)
 605 write_file_trailer (j_compress_ptr cinfo)
 606 {
 607   emit_marker(cinfo, M_EOI);
 608 }
 609
 610
 611 /*
 612  * Write an abbreviated table-specification datastream.
 613  * This consists of SOI, DQT and DHT tables, and EOI.
 614  * Any table that is defined and not marked sent_table = TRUE will be
 615  * emitted.  Note that all tables will be marked sent_table = TRUE at exit.
 616  */
 617
 618 METHODDEF(void)
 619 write_tables_only (j_compress_ptr cinfo)
 620 {
 621   int i;
 622
 623   emit_marker(cinfo, M_SOI);
 624
 625   for (i = 0; i < NUM_QUANT_TBLS; i++) {
 626     if (cinfo->quant_tbl_ptrs[i] != NULL)
 627       (void) emit_dqt(cinfo, i);
 628   }
 629
 630   if (! cinfo->arith_code) {
 631     for (i = 0; i < NUM_HUFF_TBLS; i++) {
 632       if (cinfo->dc_huff_tbl_ptrs[i] != NULL)
 633         emit_dht(cinfo, i, FALSE);
 634       if (cinfo->ac_huff_tbl_ptrs[i] != NULL)
 635         emit_dht(cinfo, i, TRUE);
 636     }
 637   }
 638
 639   emit_marker(cinfo, M_EOI);
 640 }
 641
 642
 643 /*
 644  * Initialize the marker writer module.
 645  */
 646
 647 GLOBAL(void)
 648 jinit_marker_writer (j_compress_ptr cinfo)
 649 {
 650   my_marker_ptr marker;
 651
 652   /* Create the subobject */
 653   marker = (my_marker_ptr)
 654     (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
 655                                 SIZEOF(my_marker_writer));
 656   cinfo->marker = (struct jpeg_marker_writer *) marker;
 657   /* Initialize method pointers */
 658   marker->pub.write_file_header = write_file_header;
 659   marker->pub.write_frame_header = write_frame_header;
 660   marker->pub.write_scan_header = write_scan_header;
 661   marker->pub.write_file_trailer = write_file_trailer;
 662   marker->pub.write_tables_only = write_tables_only;
 663   marker->pub.write_marker_header = write_marker_header;
 664   marker->pub.write_marker_byte = write_marker_byte;
 665   /* Initialize private state */
 666   marker->last_restart_interval = 0;
 667 }