www.pudn.com > imgport.rar > jdmarker.c, change:2008-11-05,size:42563b


/* 
 * jdmarker.c 
 * 
 * Copyright (C) 1991-1998, Thomas G. Lane. 
 * This file is part of the Independent JPEG Group's software. 
 * For conditions of distribution and use, see the accompanying README file. 
 * 
 * This file contains routines to decode JPEG datastream markers. 
 * Most of the complexity arises from our desire to support input 
 * suspension: if not all of the data for a marker is available, 
 * we must exit back to the application.  On resumption, we reprocess 
 * the marker. 
 */ 
 
#define JPEG_INTERNALS 
#include "jinclude.h" 
#include "jpeglib.h" 
 
 
typedef enum {			/* JPEG marker codes */ 
  M_SOF0  = 0xc0, 
  M_SOF1  = 0xc1, 
  M_SOF2  = 0xc2, 
  M_SOF3  = 0xc3, 
   
  M_SOF5  = 0xc5, 
  M_SOF6  = 0xc6, 
  M_SOF7  = 0xc7, 
   
  M_JPG   = 0xc8, 
  M_SOF9  = 0xc9, 
  M_SOF10 = 0xca, 
  M_SOF11 = 0xcb, 
   
  M_SOF13 = 0xcd, 
  M_SOF14 = 0xce, 
  M_SOF15 = 0xcf, 
   
  M_DHT   = 0xc4, 
   
  M_DAC   = 0xcc, 
   
  M_RST0  = 0xd0, 
  M_RST1  = 0xd1, 
  M_RST2  = 0xd2, 
  M_RST3  = 0xd3, 
  M_RST4  = 0xd4, 
  M_RST5  = 0xd5, 
  M_RST6  = 0xd6, 
  M_RST7  = 0xd7, 
   
  M_SOI   = 0xd8, 
  M_EOI   = 0xd9, 
  M_SOS   = 0xda, 
  M_DQT   = 0xdb, 
  M_DNL   = 0xdc, 
  M_DRI   = 0xdd, 
  M_DHP   = 0xde, 
  M_EXP   = 0xdf, 
   
  M_APP0  = 0xe0, 
  M_APP1  = 0xe1, 
  M_APP2  = 0xe2, 
  M_APP3  = 0xe3, 
  M_APP4  = 0xe4, 
  M_APP5  = 0xe5, 
  M_APP6  = 0xe6, 
  M_APP7  = 0xe7, 
  M_APP8  = 0xe8, 
  M_APP9  = 0xe9, 
  M_APP10 = 0xea, 
  M_APP11 = 0xeb, 
  M_APP12 = 0xec, 
  M_APP13 = 0xed, 
  M_APP14 = 0xee, 
  M_APP15 = 0xef, 
   
  M_JPG0  = 0xf0, 
  M_JPG13 = 0xfd, 
  M_COM   = 0xfe, 
   
  M_TEM   = 0x01, 
   
  M_ERROR = 0x100 
} JPEG_MARKER; 
 
 
/* Private state */ 
 
typedef struct { 
  struct jpeg_marker_reader pub; /* public fields */ 
 
  /* Application-overridable marker processing methods */ 
  jpeg_marker_parser_method process_COM; 
  jpeg_marker_parser_method process_APPn[16]; 
 
  /* Limit on marker data length to save for each marker type */ 
  unsigned int length_limit_COM; 
  unsigned int length_limit_APPn[16]; 
 
  /* Status of COM/APPn marker saving */ 
  jpeg_saved_marker_ptr cur_marker;	/* NULL if not processing a marker */ 
  unsigned int bytes_read;		/* data bytes read so far in marker */ 
  /* Note: cur_marker is not linked into marker_list until it's all read. */ 
} my_marker_reader; 
 
typedef my_marker_reader * my_marker_ptr; 
 
 
/* 
 * Macros for fetching data from the data source module. 
 * 
 * At all times, cinfo->src->next_input_byte and ->bytes_in_buffer reflect 
 * the current restart point; we update them only when we have reached a 
 * suitable place to restart if a suspension occurs. 
 */ 
 
/* Declare and initialize local copies of input pointer/count */ 
#define INPUT_VARS(cinfo)  \ 
	struct jpeg_source_mgr * datasrc = (cinfo)->src;  \ 
	const JOCTET * next_input_byte = datasrc->next_input_byte;  \ 
	size_t bytes_in_buffer = datasrc->bytes_in_buffer 
 
/* Unload the local copies --- do this only at a restart boundary */ 
#define INPUT_SYNC(cinfo)  \ 
	( datasrc->next_input_byte = next_input_byte,  \ 
	  datasrc->bytes_in_buffer = bytes_in_buffer ) 
 
/* Reload the local copies --- used only in MAKE_BYTE_AVAIL */ 
#define INPUT_RELOAD(cinfo)  \ 
	( next_input_byte = datasrc->next_input_byte,  \ 
	  bytes_in_buffer = datasrc->bytes_in_buffer ) 
 
/* Internal macro for INPUT_BYTE and INPUT_2BYTES: make a byte available. 
 * Note we do *not* do INPUT_SYNC before calling fill_input_buffer, 
 * but we must reload the local copies after a successful fill. 
 */ 
#define MAKE_BYTE_AVAIL(cinfo,action)  \ 
	if (bytes_in_buffer == 0) {  \ 
	  if (! (*datasrc->fill_input_buffer) (cinfo))  \ 
	    { action; }  \ 
	  INPUT_RELOAD(cinfo);  \ 
	} 
 
/* Read a byte into variable V. 
 * If must suspend, take the specified action (typically "return FALSE"). 
 */ 
#define INPUT_BYTE(cinfo,V,action)  \ 
	MAKESTMT( MAKE_BYTE_AVAIL(cinfo,action); \ 
		  bytes_in_buffer--; \ 
		  V = GETJOCTET(*next_input_byte++); ) 
 
/* As above, but read two bytes interpreted as an unsigned 16-bit integer. 
 * V should be declared unsigned int or perhaps INT32. 
 */ 
#define INPUT_2BYTES(cinfo,V,action)  \ 
	MAKESTMT( MAKE_BYTE_AVAIL(cinfo,action); \ 
		  bytes_in_buffer--; \ 
		  V = ((unsigned int) GETJOCTET(*next_input_byte++)) << 8; \ 
		  MAKE_BYTE_AVAIL(cinfo,action); \ 
		  bytes_in_buffer--; \ 
		  V += GETJOCTET(*next_input_byte++); ) 
 
 
/* 
 * Routines to process JPEG markers. 
 * 
 * Entry condition: JPEG marker itself has been read and its code saved 
 *   in cinfo->unread_marker; input restart point is just after the marker. 
 * 
 * Exit: if return TRUE, have read and processed any parameters, and have 
 *   updated the restart point to point after the parameters. 
 *   If return FALSE, was forced to suspend before reaching end of 
 *   marker parameters; restart point has not been moved.  Same routine 
 *   will be called again after application supplies more input data. 
 * 
 * This approach to suspension assumes that all of a marker's parameters 
 * can fit into a single input bufferload.  This should hold for "normal" 
 * markers.  Some COM/APPn markers might have large parameter segments 
 * that might not fit.  If we are simply dropping such a marker, we use 
 * skip_input_data to get past it, and thereby put the problem on the 
 * source manager's shoulders.  If we are saving the marker's contents 
 * into memory, we use a slightly different convention: when forced to 
 * suspend, the marker processor updates the restart point to the end of 
 * what it's consumed (ie, the end of the buffer) before returning FALSE. 
 * On resumption, cinfo->unread_marker still contains the marker code, 
 * but the data source will point to the next chunk of marker data. 
 * The marker processor must retain internal state to deal with this. 
 * 
 * Note that we don't bother to avoid duplicate trace messages if a 
 * suspension occurs within marker parameters.  Other side effects 
 * require more care. 
 */ 
 
 
LOCAL(boolean) 
get_soi (j_decompress_ptr cinfo) 
/* Process an SOI marker */ 
{ 
  int i; 
   
  TRACEMS(cinfo, 1, JTRC_SOI); 
 
  if (cinfo->marker->saw_SOI) 
    ERREXIT(cinfo, JERR_SOI_DUPLICATE); 
 
  /* Reset all parameters that are defined to be reset by SOI */ 
 
  for (i = 0; i < NUM_ARITH_TBLS; i++) { 
    cinfo->arith_dc_L[i] = 0; 
    cinfo->arith_dc_U[i] = 1; 
    cinfo->arith_ac_K[i] = 5; 
  } 
  cinfo->restart_interval = 0; 
 
  /* Set initial assumptions for colorspace etc */ 
 
  cinfo->jpeg_color_space = JCS_UNKNOWN; 
  cinfo->CCIR601_sampling = FALSE; /* Assume non-CCIR sampling??? */ 
 
  cinfo->saw_JFIF_marker = FALSE; 
  cinfo->JFIF_major_version = 1; /* set default JFIF APP0 values */ 
  cinfo->JFIF_minor_version = 1; 
  cinfo->density_unit = 0; 
  cinfo->X_density = 1; 
  cinfo->Y_density = 1; 
  cinfo->saw_Adobe_marker = FALSE; 
  cinfo->Adobe_transform = 0; 
 
  cinfo->marker->saw_SOI = TRUE; 
 
  return TRUE; 
} 
 
 
LOCAL(boolean) 
get_sof (j_decompress_ptr cinfo, boolean is_prog, boolean is_arith) 
/* Process a SOFn marker */ 
{ 
  JPEG_INT32 length; 
  int c, ci; 
  jpeg_component_info * compptr; 
  INPUT_VARS(cinfo); 
 
  cinfo->progressive_mode = is_prog; 
  cinfo->arith_code = is_arith; 
 
  INPUT_2BYTES(cinfo, length, return FALSE); 
 
  INPUT_BYTE(cinfo, cinfo->data_precision, return FALSE); 
  INPUT_2BYTES(cinfo, cinfo->image_height, return FALSE); 
  INPUT_2BYTES(cinfo, cinfo->image_width, return FALSE); 
  INPUT_BYTE(cinfo, cinfo->num_components, return FALSE); 
 
  length -= 8; 
 
  TRACEMS4(cinfo, 1, JTRC_SOF, cinfo->unread_marker, 
	   (int) cinfo->image_width, (int) cinfo->image_height, 
	   cinfo->num_components); 
 
  if (cinfo->marker->saw_SOF) 
    ERREXIT(cinfo, JERR_SOF_DUPLICATE); 
 
  /* We don't support files in which the image height is initially specified */ 
  /* as 0 and is later redefined by DNL.  As long as we have to check that,  */ 
  /* might as well have a general sanity check. */ 
  if (cinfo->image_height <= 0 || cinfo->image_width <= 0 
      || cinfo->num_components <= 0) 
    ERREXIT(cinfo, JERR_EMPTY_IMAGE); 
 
  if (length != (cinfo->num_components * 3)) 
    ERREXIT(cinfo, JERR_BAD_LENGTH); 
 
  if (cinfo->comp_info == NULL)	/* do only once, even if suspend */ 
    cinfo->comp_info = (jpeg_component_info *) (*cinfo->mem->alloc_small) 
			((j_common_ptr) cinfo, JPOOL_IMAGE, 
			 cinfo->num_components * SIZEOF(jpeg_component_info)); 
   
  for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components; 
       ci++, compptr++) { 
    compptr->component_index = ci; 
    INPUT_BYTE(cinfo, compptr->component_id, return FALSE); 
    INPUT_BYTE(cinfo, c, return FALSE); 
    compptr->h_samp_factor = (c >> 4) & 15; 
    compptr->v_samp_factor = (c     ) & 15; 
    INPUT_BYTE(cinfo, compptr->quant_tbl_no, return FALSE); 
 
    TRACEMS4(cinfo, 1, JTRC_SOF_COMPONENT, 
	     compptr->component_id, compptr->h_samp_factor, 
	     compptr->v_samp_factor, compptr->quant_tbl_no); 
  } 
 
  cinfo->marker->saw_SOF = TRUE; 
 
  INPUT_SYNC(cinfo); 
  return TRUE; 
} 
 
 
LOCAL(boolean) 
get_sos (j_decompress_ptr cinfo) 
/* Process a SOS marker */ 
{ 
  JPEG_INT32 length; 
  int i, ci, n, c, cc; 
  jpeg_component_info * compptr; 
  INPUT_VARS(cinfo); 
 
  if (! cinfo->marker->saw_SOF) 
    ERREXIT(cinfo, JERR_SOS_NO_SOF); 
 
  INPUT_2BYTES(cinfo, length, return FALSE); 
 
  INPUT_BYTE(cinfo, n, return FALSE); /* Number of components */ 
 
  TRACEMS1(cinfo, 1, JTRC_SOS, n); 
 
  if (length != (n * 2 + 6) || n < 1 || n > MAX_COMPS_IN_SCAN) 
    ERREXIT(cinfo, JERR_BAD_LENGTH); 
 
  cinfo->comps_in_scan = n; 
 
  /* Collect the component-spec parameters */ 
 
  for (i = 0; i < n; i++) { 
    INPUT_BYTE(cinfo, cc, return FALSE); 
    INPUT_BYTE(cinfo, c, return FALSE); 
     
    for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components; 
	 ci++, compptr++) { 
      if (cc == compptr->component_id) 
	goto id_found; 
    } 
 
    ERREXIT1(cinfo, JERR_BAD_COMPONENT_ID, cc); 
 
  id_found: 
 
    cinfo->cur_comp_info[i] = compptr; 
    compptr->dc_tbl_no = (c >> 4) & 15; 
    compptr->ac_tbl_no = (c     ) & 15; 
     
    TRACEMS3(cinfo, 1, JTRC_SOS_COMPONENT, cc, 
	     compptr->dc_tbl_no, compptr->ac_tbl_no); 
  } 
 
  /* Collect the additional scan parameters Ss, Se, Ah/Al. */ 
  INPUT_BYTE(cinfo, c, return FALSE); 
  cinfo->Ss = c; 
  INPUT_BYTE(cinfo, c, return FALSE); 
  cinfo->Se = c; 
  INPUT_BYTE(cinfo, c, return FALSE); 
  cinfo->Ah = (c >> 4) & 15; 
  cinfo->Al = (c     ) & 15; 
 
  TRACEMS4(cinfo, 1, JTRC_SOS_PARAMS, cinfo->Ss, cinfo->Se, 
	   cinfo->Ah, cinfo->Al); 
 
  /* Prepare to scan data & restart markers */ 
  cinfo->marker->next_restart_num = 0; 
 
  /* Count another SOS marker */ 
  cinfo->input_scan_number++; 
 
  INPUT_SYNC(cinfo); 
  return TRUE; 
} 
 
 
#ifdef D_ARITH_CODING_SUPPORTED 
 
LOCAL(boolean) 
get_dac (j_decompress_ptr cinfo) 
/* Process a DAC marker */ 
{ 
  JPEG_INT32 length; 
  int index, val; 
  INPUT_VARS(cinfo); 
 
  INPUT_2BYTES(cinfo, length, return FALSE); 
  length -= 2; 
   
  while (length > 0) { 
    INPUT_BYTE(cinfo, index, return FALSE); 
    INPUT_BYTE(cinfo, val, return FALSE); 
 
    length -= 2; 
 
    TRACEMS2(cinfo, 1, JTRC_DAC, index, val); 
 
    if (index < 0 || index >= (2*NUM_ARITH_TBLS)) 
      ERREXIT1(cinfo, JERR_DAC_INDEX, index); 
 
    if (index >= NUM_ARITH_TBLS) { /* define AC table */ 
      cinfo->arith_ac_K[index-NUM_ARITH_TBLS] = (UINT8) val; 
    } else {			/* define DC table */ 
      cinfo->arith_dc_L[index] = (UINT8) (val & 0x0F); 
      cinfo->arith_dc_U[index] = (UINT8) (val >> 4); 
      if (cinfo->arith_dc_L[index] > cinfo->arith_dc_U[index]) 
	ERREXIT1(cinfo, JERR_DAC_VALUE, val); 
    } 
  } 
 
  if (length != 0) 
    ERREXIT(cinfo, JERR_BAD_LENGTH); 
 
  INPUT_SYNC(cinfo); 
  return TRUE; 
} 
 
#else /* ! D_ARITH_CODING_SUPPORTED */ 
 
#define get_dac(cinfo)  skip_variable(cinfo) 
 
#endif /* D_ARITH_CODING_SUPPORTED */ 
 
 
LOCAL(boolean) 
get_dht (j_decompress_ptr cinfo) 
/* Process a DHT marker */ 
{ 
  JPEG_INT32 length; 
  UINT8 bits[17]; 
  UINT8 huffval[256]; 
  int i, index, count; 
  JHUFF_TBL **htblptr; 
  INPUT_VARS(cinfo); 
 
  INPUT_2BYTES(cinfo, length, return FALSE); 
  length -= 2; 
   
  while (length > 16) { 
    INPUT_BYTE(cinfo, index, return FALSE); 
 
    TRACEMS1(cinfo, 1, JTRC_DHT, index); 
       
    bits[0] = 0; 
    count = 0; 
    for (i = 1; i <= 16; i++) { 
      INPUT_BYTE(cinfo, bits[i], return FALSE); 
      count += bits[i]; 
    } 
 
    length -= 1 + 16; 
 
    TRACEMS8(cinfo, 2, JTRC_HUFFBITS, 
	     bits[1], bits[2], bits[3], bits[4], 
	     bits[5], bits[6], bits[7], bits[8]); 
    TRACEMS8(cinfo, 2, JTRC_HUFFBITS, 
	     bits[9], bits[10], bits[11], bits[12], 
	     bits[13], bits[14], bits[15], bits[16]); 
 
    /* Here we just do minimal validation of the counts to avoid walking 
     * off the end of our table space.  jdhuff.c will check more carefully. 
     */ 
    if (count > 256 || ((JPEG_INT32) count) > length) 
      ERREXIT(cinfo, JERR_BAD_HUFF_TABLE); 
 
    for (i = 0; i < count; i++) 
      INPUT_BYTE(cinfo, huffval[i], return FALSE); 
 
    length -= count; 
 
    if (index & 0x10) {		/* AC table definition */ 
      index -= 0x10; 
      htblptr = &cinfo->ac_huff_tbl_ptrs[index]; 
    } else {			/* DC table definition */ 
      htblptr = &cinfo->dc_huff_tbl_ptrs[index]; 
    } 
 
    if (index < 0 || index >= NUM_HUFF_TBLS) 
      ERREXIT1(cinfo, JERR_DHT_INDEX, index); 
 
    if (*htblptr == NULL) 
      *htblptr = jpeg_alloc_huff_table((j_common_ptr) cinfo); 
   
    MEMCOPY((*htblptr)->bits, bits, SIZEOF((*htblptr)->bits)); 
    MEMCOPY((*htblptr)->huffval, huffval, SIZEOF((*htblptr)->huffval)); 
  } 
 
  if (length != 0) 
    ERREXIT(cinfo, JERR_BAD_LENGTH); 
 
  INPUT_SYNC(cinfo); 
  return TRUE; 
} 
 
 
LOCAL(boolean) 
get_dqt (j_decompress_ptr cinfo) 
/* Process a DQT marker */ 
{ 
  JPEG_INT32 length; 
  int n, i, prec; 
  unsigned int tmp; 
  JQUANT_TBL *quant_ptr; 
  INPUT_VARS(cinfo); 
 
  INPUT_2BYTES(cinfo, length, return FALSE); 
  length -= 2; 
 
  while (length > 0) { 
    INPUT_BYTE(cinfo, n, return FALSE); 
    prec = n >> 4; 
    n &= 0x0F; 
 
    TRACEMS2(cinfo, 1, JTRC_DQT, n, prec); 
 
    if (n >= NUM_QUANT_TBLS) 
      ERREXIT1(cinfo, JERR_DQT_INDEX, n); 
       
    if (cinfo->quant_tbl_ptrs[n] == NULL) 
      cinfo->quant_tbl_ptrs[n] = jpeg_alloc_quant_table((j_common_ptr) cinfo); 
    quant_ptr = cinfo->quant_tbl_ptrs[n]; 
 
    for (i = 0; i < DCTSIZE2; i++) { 
      if (prec) 
	INPUT_2BYTES(cinfo, tmp, return FALSE); 
      else 
	INPUT_BYTE(cinfo, tmp, return FALSE); 
      /* We convert the zigzag-order table to natural array order. */ 
      quant_ptr->quantval[jpeg_natural_order[i]] = (UINT16) tmp; 
    } 
 
    if (cinfo->err->trace_level >= 2) { 
      for (i = 0; i < DCTSIZE2; i += 8) { 
	TRACEMS8(cinfo, 2, JTRC_QUANTVALS, 
		 quant_ptr->quantval[i],   quant_ptr->quantval[i+1], 
		 quant_ptr->quantval[i+2], quant_ptr->quantval[i+3], 
		 quant_ptr->quantval[i+4], quant_ptr->quantval[i+5], 
		 quant_ptr->quantval[i+6], quant_ptr->quantval[i+7]); 
      } 
    } 
 
    length -= DCTSIZE2+1; 
    if (prec) length -= DCTSIZE2; 
  } 
 
  if (length != 0) 
    ERREXIT(cinfo, JERR_BAD_LENGTH); 
 
  INPUT_SYNC(cinfo); 
  return TRUE; 
} 
 
 
LOCAL(boolean) 
get_dri (j_decompress_ptr cinfo) 
/* Process a DRI marker */ 
{ 
  JPEG_INT32 length; 
  unsigned int tmp; 
  INPUT_VARS(cinfo); 
 
  INPUT_2BYTES(cinfo, length, return FALSE); 
   
  if (length != 4) 
    ERREXIT(cinfo, JERR_BAD_LENGTH); 
 
  INPUT_2BYTES(cinfo, tmp, return FALSE); 
 
  TRACEMS1(cinfo, 1, JTRC_DRI, tmp); 
 
  cinfo->restart_interval = tmp; 
 
  INPUT_SYNC(cinfo); 
  return TRUE; 
} 
 
 
/* 
 * Routines for processing APPn and COM markers. 
 * These are either saved in memory or discarded, per application request. 
 * APP0 and APP14 are specially checked to see if they are 
 * JFIF and Adobe markers, respectively. 
 */ 
 
#define APP0_DATA_LEN	14	/* Length of interesting data in APP0 */ 
#define APP14_DATA_LEN	12	/* Length of interesting data in APP14 */ 
#define APPN_DATA_LEN	14	/* Must be the largest of the above!! */ 
 
 
LOCAL(void) 
examine_app0 (j_decompress_ptr cinfo, JOCTET FAR * data, 
	      unsigned int datalen, JPEG_INT32 remaining) 
/* Examine first few bytes from an APP0. 
 * Take appropriate action if it is a JFIF marker. 
 * datalen is # of bytes at data[], remaining is length of rest of marker data. 
 */ 
{ 
  JPEG_INT32 totallen = (JPEG_INT32) datalen + remaining; 
 
  if (datalen >= APP0_DATA_LEN && 
      GETJOCTET(data[0]) == 0x4A && 
      GETJOCTET(data[1]) == 0x46 && 
      GETJOCTET(data[2]) == 0x49 && 
      GETJOCTET(data[3]) == 0x46 && 
      GETJOCTET(data[4]) == 0) { 
    /* Found JFIF APP0 marker: save info */ 
    cinfo->saw_JFIF_marker = TRUE; 
    cinfo->JFIF_major_version = GETJOCTET(data[5]); 
    cinfo->JFIF_minor_version = GETJOCTET(data[6]); 
    cinfo->density_unit = GETJOCTET(data[7]); 
    cinfo->X_density = (GETJOCTET(data[8]) << 8) + GETJOCTET(data[9]); 
    cinfo->Y_density = (GETJOCTET(data[10]) << 8) + GETJOCTET(data[11]); 
    /* Check version. 
     * Major version must be 1, anything else signals an incompatible change. 
     * (We used to treat this as an error, but now it's a nonfatal warning, 
     * because some bozo at Hijaak couldn't read the spec.) 
     * Minor version should be 0..2, but process anyway if newer. 
     */ 
    if (cinfo->JFIF_major_version != 1) 
      WARNMS2(cinfo, JWRN_JFIF_MAJOR, 
	      cinfo->JFIF_major_version, cinfo->JFIF_minor_version); 
    /* Generate trace messages */ 
    TRACEMS5(cinfo, 1, JTRC_JFIF, 
	     cinfo->JFIF_major_version, cinfo->JFIF_minor_version, 
	     cinfo->X_density, cinfo->Y_density, cinfo->density_unit); 
    /* Validate thumbnail dimensions and issue appropriate messages */ 
    if (GETJOCTET(data[12]) | GETJOCTET(data[13])) 
      TRACEMS2(cinfo, 1, JTRC_JFIF_THUMBNAIL, 
	       GETJOCTET(data[12]), GETJOCTET(data[13])); 
    totallen -= APP0_DATA_LEN; 
    if (totallen != 
	((JPEG_INT32)GETJOCTET(data[12]) * (JPEG_INT32)GETJOCTET(data[13]) * (JPEG_INT32) 3)) 
      TRACEMS1(cinfo, 1, JTRC_JFIF_BADTHUMBNAILSIZE, (int) totallen); 
  } else if (datalen >= 6 && 
      GETJOCTET(data[0]) == 0x4A && 
      GETJOCTET(data[1]) == 0x46 && 
      GETJOCTET(data[2]) == 0x58 && 
      GETJOCTET(data[3]) == 0x58 && 
      GETJOCTET(data[4]) == 0) { 
    /* Found JFIF "JFXX" extension APP0 marker */ 
    /* The library doesn't actually do anything with these, 
     * but we try to produce a helpful trace message. 
     */ 
    switch (GETJOCTET(data[5])) { 
    case 0x10: 
      TRACEMS1(cinfo, 1, JTRC_THUMB_JPEG, (int) totallen); 
      break; 
    case 0x11: 
      TRACEMS1(cinfo, 1, JTRC_THUMB_PALETTE, (int) totallen); 
      break; 
    case 0x13: 
      TRACEMS1(cinfo, 1, JTRC_THUMB_RGB, (int) totallen); 
      break; 
    default: 
      TRACEMS2(cinfo, 1, JTRC_JFIF_EXTENSION, 
	       GETJOCTET(data[5]), (int) totallen); 
      break; 
    } 
  } else { 
    /* Start of APP0 does not match "JFIF" or "JFXX", or too short */ 
    TRACEMS1(cinfo, 1, JTRC_APP0, (int) totallen); 
  } 
} 
 
 
LOCAL(void) 
examine_app14 (j_decompress_ptr cinfo, JOCTET FAR * data, 
	       unsigned int datalen, JPEG_INT32 remaining) 
/* Examine first few bytes from an APP14. 
 * Take appropriate action if it is an Adobe marker. 
 * datalen is # of bytes at data[], remaining is length of rest of marker data. 
 */ 
{ 
  unsigned int version, flags0, flags1, transform; 
 
  if (datalen >= APP14_DATA_LEN && 
      GETJOCTET(data[0]) == 0x41 && 
      GETJOCTET(data[1]) == 0x64 && 
      GETJOCTET(data[2]) == 0x6F && 
      GETJOCTET(data[3]) == 0x62 && 
      GETJOCTET(data[4]) == 0x65) { 
    /* Found Adobe APP14 marker */ 
    version = (GETJOCTET(data[5]) << 8) + GETJOCTET(data[6]); 
    flags0 = (GETJOCTET(data[7]) << 8) + GETJOCTET(data[8]); 
    flags1 = (GETJOCTET(data[9]) << 8) + GETJOCTET(data[10]); 
    transform = GETJOCTET(data[11]); 
    TRACEMS4(cinfo, 1, JTRC_ADOBE, version, flags0, flags1, transform); 
    cinfo->saw_Adobe_marker = TRUE; 
    cinfo->Adobe_transform = (UINT8) transform; 
  } else { 
    /* Start of APP14 does not match "Adobe", or too short */ 
    TRACEMS1(cinfo, 1, JTRC_APP14, (int) (datalen + remaining)); 
  } 
} 
 
 
METHODDEF(boolean) 
get_interesting_appn (j_decompress_ptr cinfo) 
/* Process an APP0 or APP14 marker without saving it */ 
{ 
  JPEG_INT32 length; 
  JOCTET b[APPN_DATA_LEN]; 
  unsigned int i, numtoread; 
  INPUT_VARS(cinfo); 
 
  INPUT_2BYTES(cinfo, length, return FALSE); 
  length -= 2; 
 
  /* get the interesting part of the marker data */ 
  if (length >= APPN_DATA_LEN) 
    numtoread = APPN_DATA_LEN; 
  else if (length > 0) 
    numtoread = (unsigned int) length; 
  else 
    numtoread = 0; 
  for (i = 0; i < numtoread; i++) 
    INPUT_BYTE(cinfo, b[i], return FALSE); 
  length -= numtoread; 
 
  /* process it */ 
  switch (cinfo->unread_marker) { 
  case M_APP0: 
    examine_app0(cinfo, (JOCTET FAR *) b, numtoread, length); 
    break; 
  case M_APP14: 
    examine_app14(cinfo, (JOCTET FAR *) b, numtoread, length); 
    break; 
  default: 
    /* can't get here unless jpeg_save_markers chooses wrong processor */ 
    ERREXIT1(cinfo, JERR_UNKNOWN_MARKER, cinfo->unread_marker); 
    break; 
  } 
 
  /* skip any remaining data -- could be lots */ 
  INPUT_SYNC(cinfo); 
  if (length > 0) 
    (*cinfo->src->skip_input_data) (cinfo, (long) length); 
 
  return TRUE; 
} 
 
 
#ifdef SAVE_MARKERS_SUPPORTED 
 
METHODDEF(boolean) 
save_marker (j_decompress_ptr cinfo) 
/* Save an APPn or COM marker into the marker list */ 
{ 
  my_marker_ptr marker = (my_marker_ptr) cinfo->marker; 
  jpeg_saved_marker_ptr cur_marker = marker->cur_marker; 
  unsigned int bytes_read, data_length; 
  JOCTET FAR * data; 
  JPEG_INT32 length = 0; 
  INPUT_VARS(cinfo); 
 
  if (cur_marker == NULL) { 
    /* begin reading a marker */ 
    INPUT_2BYTES(cinfo, length, return FALSE); 
    length -= 2; 
    if (length >= 0) {		/* watch out for bogus length word */ 
      /* figure out how much we want to save */ 
      unsigned int limit; 
      if (cinfo->unread_marker == (int) M_COM) 
	limit = marker->length_limit_COM; 
      else 
	limit = marker->length_limit_APPn[cinfo->unread_marker - (int) M_APP0]; 
      if ((unsigned int) length < limit) 
	limit = (unsigned int) length; 
      /* allocate and initialize the marker item */ 
      cur_marker = (jpeg_saved_marker_ptr) 
	(*cinfo->mem->alloc_large) ((j_common_ptr) cinfo, JPOOL_IMAGE, 
				    SIZEOF(struct jpeg_marker_struct) + limit); 
      cur_marker->next = NULL; 
      cur_marker->marker = (UINT8) cinfo->unread_marker; 
      cur_marker->original_length = (unsigned int) length; 
      cur_marker->data_length = limit; 
      /* data area is just beyond the jpeg_marker_struct */ 
      data = cur_marker->data = (JOCTET FAR *) (cur_marker + 1); 
      marker->cur_marker = cur_marker; 
      marker->bytes_read = 0; 
      bytes_read = 0; 
      data_length = limit; 
    } else { 
      /* deal with bogus length word */ 
      bytes_read = data_length = 0; 
      data = NULL; 
    } 
  } else { 
    /* resume reading a marker */ 
    bytes_read = marker->bytes_read; 
    data_length = cur_marker->data_length; 
    data = cur_marker->data + bytes_read; 
  } 
 
  while (bytes_read < data_length) { 
    INPUT_SYNC(cinfo);		/* move the restart point to here */ 
    marker->bytes_read = bytes_read; 
    /* If there's not at least one byte in buffer, suspend */ 
    MAKE_BYTE_AVAIL(cinfo, return FALSE); 
    /* Copy bytes with reasonable rapidity */ 
    while (bytes_read < data_length && bytes_in_buffer > 0) { 
      *data++ = *next_input_byte++; 
      bytes_in_buffer--; 
      bytes_read++; 
    } 
  } 
 
  /* Done reading what we want to read */ 
  if (cur_marker != NULL) {	/* will be NULL if bogus length word */ 
    /* Add new marker to end of list */ 
    if (cinfo->marker_list == NULL) { 
      cinfo->marker_list = cur_marker; 
    } else { 
      jpeg_saved_marker_ptr prev = cinfo->marker_list; 
      while (prev->next != NULL) 
	prev = prev->next; 
      prev->next = cur_marker; 
    } 
    /* Reset pointer & calc remaining data length */ 
    data = cur_marker->data; 
    length = cur_marker->original_length - data_length; 
  } 
  /* Reset to initial state for next marker */ 
  marker->cur_marker = NULL; 
 
  /* Process the marker if interesting; else just make a generic trace msg */ 
  switch (cinfo->unread_marker) { 
  case M_APP0: 
    examine_app0(cinfo, data, data_length, length); 
    break; 
  case M_APP14: 
    examine_app14(cinfo, data, data_length, length); 
    break; 
  default: 
    TRACEMS2(cinfo, 1, JTRC_MISC_MARKER, cinfo->unread_marker, 
	     (int) (data_length + length)); 
    break; 
  } 
 
  /* skip any remaining data -- could be lots */ 
  INPUT_SYNC(cinfo);		/* do before skip_input_data */ 
  if (length > 0) 
    (*cinfo->src->skip_input_data) (cinfo, (long) length); 
 
  return TRUE; 
} 
 
#endif /* SAVE_MARKERS_SUPPORTED */ 
 
 
METHODDEF(boolean) 
skip_variable (j_decompress_ptr cinfo) 
/* Skip over an unknown or uninteresting variable-length marker */ 
{ 
  JPEG_INT32 length; 
  INPUT_VARS(cinfo); 
 
  INPUT_2BYTES(cinfo, length, return FALSE); 
  length -= 2; 
   
  TRACEMS2(cinfo, 1, JTRC_MISC_MARKER, cinfo->unread_marker, (int) length); 
 
  INPUT_SYNC(cinfo);		/* do before skip_input_data */ 
  if (length > 0) 
    (*cinfo->src->skip_input_data) (cinfo, (long) length); 
 
  return TRUE; 
} 
 
 
/* 
 * Find the next JPEG marker, save it in cinfo->unread_marker. 
 * Returns FALSE if had to suspend before reaching a marker; 
 * in that case cinfo->unread_marker is unchanged. 
 * 
 * Note that the result might not be a valid marker code, 
 * but it will never be 0 or FF. 
 */ 
 
LOCAL(boolean) 
next_marker (j_decompress_ptr cinfo) 
{ 
  int c; 
  INPUT_VARS(cinfo); 
 
  for (;;) { 
    INPUT_BYTE(cinfo, c, return FALSE); 
    /* Skip any non-FF bytes. 
     * This may look a bit inefficient, but it will not occur in a valid file. 
     * We sync after each discarded byte so that a suspending data source 
     * can discard the byte from its buffer. 
     */ 
    while (c != 0xFF) { 
      cinfo->marker->discarded_bytes++; 
      INPUT_SYNC(cinfo); 
      INPUT_BYTE(cinfo, c, return FALSE); 
    } 
    /* This loop swallows any duplicate FF bytes.  Extra FFs are legal as 
     * pad bytes, so don't count them in discarded_bytes.  We assume there 
     * will not be so many consecutive FF bytes as to overflow a suspending 
     * data source's input buffer. 
     */ 
    do { 
      INPUT_BYTE(cinfo, c, return FALSE); 
    } while (c == 0xFF); 
    if (c != 0) 
      break;			/* found a valid marker, exit loop */ 
    /* Reach here if we found a stuffed-zero data sequence (FF/00). 
     * Discard it and loop back to try again. 
     */ 
    cinfo->marker->discarded_bytes += 2; 
    INPUT_SYNC(cinfo); 
  } 
 
  if (cinfo->marker->discarded_bytes != 0) { 
    WARNMS2(cinfo, JWRN_EXTRANEOUS_DATA, cinfo->marker->discarded_bytes, c); 
    cinfo->marker->discarded_bytes = 0; 
  } 
 
  cinfo->unread_marker = c; 
 
  INPUT_SYNC(cinfo); 
  return TRUE; 
} 
 
 
LOCAL(boolean) 
first_marker (j_decompress_ptr cinfo) 
/* Like next_marker, but used to obtain the initial SOI marker. */ 
/* For this marker, we do not allow preceding garbage or fill; otherwise, 
 * we might well scan an entire input file before realizing it ain't JPEG. 
 * If an application wants to process non-JFIF files, it must seek to the 
 * SOI before calling the JPEG library. 
 */ 
{ 
  int c, c2; 
  INPUT_VARS(cinfo); 
 
  INPUT_BYTE(cinfo, c, return FALSE); 
  INPUT_BYTE(cinfo, c2, return FALSE); 
  if (c != 0xFF || c2 != (int) M_SOI) 
    ERREXIT2(cinfo, JERR_NO_SOI, c, c2); 
 
  cinfo->unread_marker = c2; 
 
  INPUT_SYNC(cinfo); 
  return TRUE; 
} 
 
 
/* 
 * Read markers until SOS or EOI. 
 * 
 * Returns same codes as are defined for jpeg_consume_input: 
 * JPEG_SUSPENDED, JPEG_REACHED_SOS, or JPEG_REACHED_EOI. 
 */ 
 
METHODDEF(int) 
read_markers (j_decompress_ptr cinfo) 
{ 
  /* Outer loop repeats once for each marker. */ 
  for (;;) { 
    /* Collect the marker proper, unless we already did. */ 
    /* NB: first_marker() enforces the requirement that SOI appear first. */ 
    if (cinfo->unread_marker == 0) { 
      if (! cinfo->marker->saw_SOI) { 
	if (! first_marker(cinfo)) 
	  return JPEG_SUSPENDED; 
      } else { 
	if (! next_marker(cinfo)) 
	  return JPEG_SUSPENDED; 
      } 
    } 
    /* At this point cinfo->unread_marker contains the marker code and the 
     * input point is just past the marker proper, but before any parameters. 
     * A suspension will cause us to return with this state still true. 
     */ 
    switch (cinfo->unread_marker) { 
    case M_SOI: 
      if (! get_soi(cinfo)) 
	return JPEG_SUSPENDED; 
      break; 
 
    case M_SOF0:		/* Baseline */ 
    case M_SOF1:		/* Extended sequential, Huffman */ 
      if (! get_sof(cinfo, FALSE, FALSE)) 
	return JPEG_SUSPENDED; 
      break; 
 
    case M_SOF2:		/* Progressive, Huffman */ 
      if (! get_sof(cinfo, TRUE, FALSE)) 
	return JPEG_SUSPENDED; 
      break; 
 
    case M_SOF9:		/* Extended sequential, arithmetic */ 
      if (! get_sof(cinfo, FALSE, TRUE)) 
	return JPEG_SUSPENDED; 
      break; 
 
    case M_SOF10:		/* Progressive, arithmetic */ 
      if (! get_sof(cinfo, TRUE, TRUE)) 
	return JPEG_SUSPENDED; 
      break; 
 
    /* Currently unsupported SOFn types */ 
    case M_SOF3:		/* Lossless, Huffman */ 
    case M_SOF5:		/* Differential sequential, Huffman */ 
    case M_SOF6:		/* Differential progressive, Huffman */ 
    case M_SOF7:		/* Differential lossless, Huffman */ 
    case M_JPG:			/* Reserved for JPEG extensions */ 
    case M_SOF11:		/* Lossless, arithmetic */ 
    case M_SOF13:		/* Differential sequential, arithmetic */ 
    case M_SOF14:		/* Differential progressive, arithmetic */ 
    case M_SOF15:		/* Differential lossless, arithmetic */ 
      ERREXIT1(cinfo, JERR_SOF_UNSUPPORTED, cinfo->unread_marker); 
      break; 
 
    case M_SOS: 
      if (! get_sos(cinfo)) 
	return JPEG_SUSPENDED; 
      cinfo->unread_marker = 0;	/* processed the marker */ 
      return JPEG_REACHED_SOS; 
     
    case M_EOI: 
      TRACEMS(cinfo, 1, JTRC_EOI); 
      cinfo->unread_marker = 0;	/* processed the marker */ 
      return JPEG_REACHED_EOI; 
       
    case M_DAC: 
      if (! get_dac(cinfo)) 
	return JPEG_SUSPENDED; 
      break; 
       
    case M_DHT: 
      if (! get_dht(cinfo)) 
	return JPEG_SUSPENDED; 
      break; 
       
    case M_DQT: 
      if (! get_dqt(cinfo)) 
	return JPEG_SUSPENDED; 
      break; 
       
    case M_DRI: 
      if (! get_dri(cinfo)) 
	return JPEG_SUSPENDED; 
      break; 
       
    case M_APP0: 
    case M_APP1: 
    case M_APP2: 
    case M_APP3: 
    case M_APP4: 
    case M_APP5: 
    case M_APP6: 
    case M_APP7: 
    case M_APP8: 
    case M_APP9: 
    case M_APP10: 
    case M_APP11: 
    case M_APP12: 
    case M_APP13: 
    case M_APP14: 
    case M_APP15: 
      if (! (*((my_marker_ptr) cinfo->marker)->process_APPn[ 
		cinfo->unread_marker - (int) M_APP0]) (cinfo)) 
	return JPEG_SUSPENDED; 
      break; 
       
    case M_COM: 
      if (! (*((my_marker_ptr) cinfo->marker)->process_COM) (cinfo)) 
	return JPEG_SUSPENDED; 
      break; 
 
    case M_RST0:		/* these are all parameterless */ 
    case M_RST1: 
    case M_RST2: 
    case M_RST3: 
    case M_RST4: 
    case M_RST5: 
    case M_RST6: 
    case M_RST7: 
    case M_TEM: 
      TRACEMS1(cinfo, 1, JTRC_PARMLESS_MARKER, cinfo->unread_marker); 
      break; 
 
    case M_DNL:			/* Ignore DNL ... perhaps the wrong thing */ 
      if (! skip_variable(cinfo)) 
	return JPEG_SUSPENDED; 
      break; 
 
    default:			/* must be DHP, EXP, JPGn, or RESn */ 
      /* For now, we treat the reserved markers as fatal errors since they are 
       * likely to be used to signal incompatible JPEG Part 3 extensions. 
       * Once the JPEG 3 version-number marker is well defined, this code 
       * ought to change! 
       */ 
      ERREXIT1(cinfo, JERR_UNKNOWN_MARKER, cinfo->unread_marker); 
      break; 
    } 
    /* Successfully processed marker, so reset state variable */ 
    cinfo->unread_marker = 0; 
  } /* end loop */ 
} 
 
 
/* 
 * Read a restart marker, which is expected to appear next in the datastream; 
 * if the marker is not there, take appropriate recovery action. 
 * Returns FALSE if suspension is required. 
 * 
 * This is called by the entropy decoder after it has read an appropriate 
 * number of MCUs.  cinfo->unread_marker may be nonzero if the entropy decoder 
 * has already read a marker from the data source.  Under normal conditions 
 * cinfo->unread_marker will be reset to 0 before returning; if not reset, 
 * it holds a marker which the decoder will be unable to read past. 
 */ 
 
METHODDEF(boolean) 
read_restart_marker (j_decompress_ptr cinfo) 
{ 
  /* Obtain a marker unless we already did. */ 
  /* Note that next_marker will complain if it skips any data. */ 
  if (cinfo->unread_marker == 0) { 
    if (! next_marker(cinfo)) 
      return FALSE; 
  } 
 
  if (cinfo->unread_marker == 
      ((int) M_RST0 + cinfo->marker->next_restart_num)) { 
    /* Normal case --- swallow the marker and let entropy decoder continue */ 
    TRACEMS1(cinfo, 3, JTRC_RST, cinfo->marker->next_restart_num); 
    cinfo->unread_marker = 0; 
  } else { 
    /* Uh-oh, the restart markers have been messed up. */ 
    /* Let the data source manager determine how to resync. */ 
    if (! (*cinfo->src->resync_to_restart) (cinfo, 
					    cinfo->marker->next_restart_num)) 
      return FALSE; 
  } 
 
  /* Update next-restart state */ 
  cinfo->marker->next_restart_num = (cinfo->marker->next_restart_num + 1) & 7; 
 
  return TRUE; 
} 
 
 
/* 
 * This is the default resync_to_restart method for data source managers 
 * to use if they don't have any better approach.  Some data source managers 
 * may be able to back up, or may have additional knowledge about the data 
 * which permits a more intelligent recovery strategy; such managers would 
 * presumably supply their own resync method. 
 * 
 * read_restart_marker calls resync_to_restart if it finds a marker other than 
 * the restart marker it was expecting.  (This code is *not* used unless 
 * a nonzero restart interval has been declared.)  cinfo->unread_marker is 
 * the marker code actually found (might be anything, except 0 or FF). 
 * The desired restart marker number (0..7) is passed as a parameter. 
 * This routine is supposed to apply whatever error recovery strategy seems 
 * appropriate in order to position the input stream to the next data segment. 
 * Note that cinfo->unread_marker is treated as a marker appearing before 
 * the current data-source input point; usually it should be reset to zero 
 * before returning. 
 * Returns FALSE if suspension is required. 
 * 
 * This implementation is substantially constrained by wanting to treat the 
 * input as a data stream; this means we can't back up.  Therefore, we have 
 * only the following actions to work with: 
 *   1. Simply discard the marker and let the entropy decoder resume at next 
 *      byte of file. 
 *   2. Read forward until we find another marker, discarding intervening 
 *      data.  (In theory we could look ahead within the current bufferload, 
 *      without having to discard data if we don't find the desired marker. 
 *      This idea is not implemented here, in part because it makes behavior 
 *      dependent on buffer size and chance buffer-boundary positions.) 
 *   3. Leave the marker unread (by failing to zero cinfo->unread_marker). 
 *      This will cause the entropy decoder to process an empty data segment, 
 *      inserting dummy zeroes, and then we will reprocess the marker. 
 * 
 * #2 is appropriate if we think the desired marker lies ahead, while #3 is 
 * appropriate if the found marker is a future restart marker (indicating 
 * that we have missed the desired restart marker, probably because it got 
 * corrupted). 
 * We apply #2 or #3 if the found marker is a restart marker no more than 
 * two counts behind or ahead of the expected one.  We also apply #2 if the 
 * found marker is not a legal JPEG marker code (it's certainly bogus data). 
 * If the found marker is a restart marker more than 2 counts away, we do #1 
 * (too much risk that the marker is erroneous; with luck we will be able to 
 * resync at some future point). 
 * For any valid non-restart JPEG marker, we apply #3.  This keeps us from 
 * overrunning the end of a scan.  An implementation limited to single-scan 
 * files might find it better to apply #2 for markers other than EOI, since 
 * any other marker would have to be bogus data in that case. 
 */ 
 
GLOBAL(boolean) 
jpeg_resync_to_restart (j_decompress_ptr cinfo, int desired) 
{ 
  int marker = cinfo->unread_marker; 
  int action = 1; 
   
  /* Always put up a warning. */ 
  WARNMS2(cinfo, JWRN_MUST_RESYNC, marker, desired); 
   
  /* Outer loop handles repeated decision after scanning forward. */ 
  for (;;) { 
    if (marker < (int) M_SOF0) 
      action = 2;		/* invalid marker */ 
    else if (marker < (int) M_RST0 || marker > (int) M_RST7) 
      action = 3;		/* valid non-restart marker */ 
    else { 
      if (marker == ((int) M_RST0 + ((desired+1) & 7)) || 
	  marker == ((int) M_RST0 + ((desired+2) & 7))) 
	action = 3;		/* one of the next two expected restarts */ 
      else if (marker == ((int) M_RST0 + ((desired-1) & 7)) || 
	       marker == ((int) M_RST0 + ((desired-2) & 7))) 
	action = 2;		/* a prior restart, so advance */ 
      else 
	action = 1;		/* desired restart or too far away */ 
    } 
    TRACEMS2(cinfo, 4, JTRC_RECOVERY_ACTION, marker, action); 
    switch (action) { 
    case 1: 
      /* Discard marker and let entropy decoder resume processing. */ 
      cinfo->unread_marker = 0; 
      return TRUE; 
    case 2: 
      /* Scan to the next marker, and repeat the decision loop. */ 
      if (! next_marker(cinfo)) 
	return FALSE; 
      marker = cinfo->unread_marker; 
      break; 
    case 3: 
      /* Return without advancing past this marker. */ 
      /* Entropy decoder will be forced to process an empty segment. */ 
      return TRUE; 
    } 
  } /* end loop */ 
} 
 
 
/* 
 * Reset marker processing state to begin a fresh datastream. 
 */ 
 
METHODDEF(void) 
reset_marker_reader (j_decompress_ptr cinfo) 
{ 
  my_marker_ptr marker = (my_marker_ptr) cinfo->marker; 
 
  cinfo->comp_info = NULL;		/* until allocated by get_sof */ 
  cinfo->input_scan_number = 0;		/* no SOS seen yet */ 
  cinfo->unread_marker = 0;		/* no pending marker */ 
  marker->pub.saw_SOI = FALSE;		/* set internal state too */ 
  marker->pub.saw_SOF = FALSE; 
  marker->pub.discarded_bytes = 0; 
  marker->cur_marker = NULL; 
} 
 
 
/* 
 * Initialize the marker reader module. 
 * This is called only once, when the decompression object is created. 
 */ 
 
GLOBAL(void) 
jinit_marker_reader (j_decompress_ptr cinfo) 
{ 
  my_marker_ptr marker; 
  int i; 
 
  /* Create subobject in permanent pool */ 
  marker = (my_marker_ptr) 
    (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_PERMANENT, 
				SIZEOF(my_marker_reader)); 
  cinfo->marker = (struct jpeg_marker_reader *) marker; 
  /* Initialize public method pointers */ 
  marker->pub.reset_marker_reader = reset_marker_reader; 
  marker->pub.read_markers = read_markers; 
  marker->pub.read_restart_marker = read_restart_marker; 
  /* Initialize COM/APPn processing. 
   * By default, we examine and then discard APP0 and APP14, 
   * but simply discard COM and all other APPn. 
   */ 
  marker->process_COM = skip_variable; 
  marker->length_limit_COM = 0; 
  for (i = 0; i < 16; i++) { 
    marker->process_APPn[i] = skip_variable; 
    marker->length_limit_APPn[i] = 0; 
  } 
  marker->process_APPn[0] = get_interesting_appn; 
  marker->process_APPn[14] = get_interesting_appn; 
  /* Reset marker processing state */ 
  reset_marker_reader(cinfo); 
} 
 
 
/* 
 * Control saving of COM and APPn markers into marker_list. 
 */ 
 
#ifdef SAVE_MARKERS_SUPPORTED 
 
GLOBAL(void) 
jpeg_save_markers (j_decompress_ptr cinfo, int marker_code, 
		   unsigned int length_limit) 
{ 
  my_marker_ptr marker = (my_marker_ptr) cinfo->marker; 
  long maxlength; 
  jpeg_marker_parser_method processor; 
 
  /* Length limit mustn't be larger than what we can allocate 
   * (should only be a concern in a 16-bit environment). 
   */ 
  maxlength = cinfo->mem->max_alloc_chunk - SIZEOF(struct jpeg_marker_struct); 
  if (((long) length_limit) > maxlength) 
    length_limit = (unsigned int) maxlength; 
 
  /* Choose processor routine to use. 
   * APP0/APP14 have special requirements. 
   */ 
  if (length_limit) { 
    processor = save_marker; 
    /* If saving APP0/APP14, save at least enough for our internal use. */ 
    if (marker_code == (int) M_APP0 && length_limit < APP0_DATA_LEN) 
      length_limit = APP0_DATA_LEN; 
    else if (marker_code == (int) M_APP14 && length_limit < APP14_DATA_LEN) 
      length_limit = APP14_DATA_LEN; 
  } else { 
    processor = skip_variable; 
    /* If discarding APP0/APP14, use our regular on-the-fly processor. */ 
    if (marker_code == (int) M_APP0 || marker_code == (int) M_APP14) 
      processor = get_interesting_appn; 
  } 
 
  if (marker_code == (int) M_COM) { 
    marker->process_COM = processor; 
    marker->length_limit_COM = length_limit; 
  } else if (marker_code >= (int) M_APP0 && marker_code <= (int) M_APP15) { 
    marker->process_APPn[marker_code - (int) M_APP0] = processor; 
    marker->length_limit_APPn[marker_code - (int) M_APP0] = length_limit; 
  } else 
    ERREXIT1(cinfo, JERR_UNKNOWN_MARKER, marker_code); 
} 
 
#endif /* SAVE_MARKERS_SUPPORTED */ 
 
 
/* 
 * Install a special processing method for COM or APPn markers. 
 */ 
 
GLOBAL(void) 
jpeg_set_marker_processor (j_decompress_ptr cinfo, int marker_code, 
			   jpeg_marker_parser_method routine) 
{ 
  my_marker_ptr marker = (my_marker_ptr) cinfo->marker; 
 
  if (marker_code == (int) M_COM) 
    marker->process_COM = routine; 
  else if (marker_code >= (int) M_APP0 && marker_code <= (int) M_APP15) 
    marker->process_APPn[marker_code - (int) M_APP0] = routine; 
  else 
    ERREXIT1(cinfo, JERR_UNKNOWN_MARKER, marker_code); 
}