/*

 * jdmarker.c

 *

 * Copyright (C) 1991-1998, Thomas G. Lane.

 * Modified 2009-2012 by Guido Vollbeding.

 * 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_JPG8  = 0xf8,

  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->color_transform = JCT_NONE;

  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_baseline, boolean is_prog,

	 boolean is_arith)

/* Process a SOFn marker */

{

  INT32 length;

  int c, ci, i;

  jpeg_component_info * compptr;

  INPUT_VARS(cinfo);

  cinfo->is_baseline = is_baseline;

  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; ci < cinfo->num_components; ci++) {

    INPUT_BYTE(cinfo, c, return FALSE);

    /* Check to see whether component id has already been seen   */

    /* (in violation of the spec, but unfortunately seen in some */

    /* files).  If so, create "fake" component id equal to the   */

    /* max id seen so far + 1. */

    for (i = 0, compptr = cinfo->comp_info; i < ci; i++, compptr++) {

      if (c == compptr->component_id) {

	compptr = cinfo->comp_info;

	c = compptr->component_id;

	compptr++;

	for (i = 1; i < ci; i++, compptr++) {

	  if (compptr->component_id > c) c = compptr->component_id;

	}

	c++;

	break;

      }

    }

    compptr->component_id = c;

    compptr->component_index = ci;

    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 */

{

  INT32 length;

  int c, ci, i, n;

  jpeg_component_info * compptr;

  INPUT_VARS(cinfo);

  if (! cinfo->marker->saw_SOF)

    ERREXITS(cinfo, JERR_SOF_BEFORE, "SOS");

  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 > MAX_COMPS_IN_SCAN ||

      (n == 0 && !cinfo->progressive_mode))

      /* pseudo SOS marker only allowed in progressive mode */

    ERREXIT(cinfo, JERR_BAD_LENGTH);

  cinfo->comps_in_scan = n;

  /* Collect the component-spec parameters */

  for (i = 0; i < n; i++) {

    INPUT_BYTE(cinfo, c, return FALSE);

    /* Detect the case where component id's are not unique, and, if so, */

    /* create a fake component id using the same logic as in get_sof.   */

    for (ci = 0; ci < i; ci++) {

      if (c == cinfo->cur_comp_info[ci]->component_id) {

	c = cinfo->cur_comp_info[0]->component_id;

	for (ci = 1; ci < i; ci++) {

	  compptr = cinfo->cur_comp_info[ci];

	  if (compptr->component_id > c) c = compptr->component_id;

	}

	c++;

	break;

      }

    }

    for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;

	 ci++, compptr++) {

      if (c == compptr->component_id)

	goto id_found;

    }

    ERREXIT1(cinfo, JERR_BAD_COMPONENT_ID, c);

  id_found:

    cinfo->cur_comp_info[i] = compptr;

    INPUT_BYTE(cinfo, c, return FALSE);

    compptr->dc_tbl_no = (c >> 4) & 15;

    compptr->ac_tbl_no = (c     ) & 15;

    TRACEMS3(cinfo, 1, JTRC_SOS_COMPONENT, compptr->component_id,

	     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 (non-pseudo) SOS marker */

  if (n) 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 */

{

  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 */

{

  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 || ((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 */

{

  INT32 length, count, i;

  int n, prec;

  unsigned int tmp;

  JQUANT_TBL *quant_ptr;

  const int *natural_order;

  INPUT_VARS(cinfo);

  INPUT_2BYTES(cinfo, length, return FALSE);

  length -= 2;

  while (length > 0) {

    length--;

    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];

    if (prec) {

      if (length < DCTSIZE2 * 2) {

	/* Initialize full table for safety. */

	for (i = 0; i < DCTSIZE2; i++) {

	  quant_ptr->quantval[i] = 1;

	}

	count = length >> 1;

      } else

	count = DCTSIZE2;

    } else {

      if (length < DCTSIZE2) {

	/* Initialize full table for safety. */

	for (i = 0; i < DCTSIZE2; i++) {

	  quant_ptr->quantval[i] = 1;

	}

	count = length;

      } else

	count = DCTSIZE2;

    }

    switch (count) {

    case (2*2): natural_order = jpeg_natural_order2; break;

    case (3*3): natural_order = jpeg_natural_order3; break;

    case (4*4): natural_order = jpeg_natural_order4; break;

    case (5*5): natural_order = jpeg_natural_order5; break;

    case (6*6): natural_order = jpeg_natural_order6; break;

    case (7*7): natural_order = jpeg_natural_order7; break;

    default:    natural_order = jpeg_natural_order;  break;

    }

    for (i = 0; i < count; 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[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 -= count;

    if (prec) length -= count;

  }

  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 */

{

  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;

}

LOCAL(boolean)

get_lse (j_decompress_ptr cinfo)

/* Process an LSE marker */

{

  INT32 length;

  unsigned int tmp;

  int cid;

  INPUT_VARS(cinfo);

  if (! cinfo->marker->saw_SOF)

    ERREXITS(cinfo, JERR_SOF_BEFORE, "LSE");

  if (cinfo->num_components < 3) goto bad;

  INPUT_2BYTES(cinfo, length, return FALSE);

  if (length != 24)

    ERREXIT(cinfo, JERR_BAD_LENGTH);

  INPUT_BYTE(cinfo, tmp, return FALSE);

  if (tmp != 0x0D)	/* ID inverse transform specification */

    ERREXIT1(cinfo, JERR_UNKNOWN_MARKER, cinfo->unread_marker);

  INPUT_2BYTES(cinfo, tmp, return FALSE);

  if (tmp != MAXJSAMPLE) goto bad;		/* MAXTRANS */

  INPUT_BYTE(cinfo, tmp, return FALSE);

  if (tmp != 3) goto bad;			/* Nt=3 */

  INPUT_BYTE(cinfo, cid, return FALSE);

  if (cid != cinfo->comp_info[1].component_id) goto bad;

  INPUT_BYTE(cinfo, cid, return FALSE);

  if (cid != cinfo->comp_info[0].component_id) goto bad;

  INPUT_BYTE(cinfo, cid, return FALSE);

  if (cid != cinfo->comp_info[2].component_id) goto bad;

  INPUT_BYTE(cinfo, tmp, return FALSE);

  if (tmp != 0x80) goto bad;		/* F1: CENTER1=1, NORM1=0 */

  INPUT_2BYTES(cinfo, tmp, return FALSE);

  if (tmp != 0) goto bad;			/* A(1,1)=0 */

  INPUT_2BYTES(cinfo, tmp, return FALSE);

  if (tmp != 0) goto bad;			/* A(1,2)=0 */

  INPUT_BYTE(cinfo, tmp, return FALSE);

  if (tmp != 0) goto bad;		/* F2: CENTER2=0, NORM2=0 */

  INPUT_2BYTES(cinfo, tmp, return FALSE);

  if (tmp != 1) goto bad;			/* A(2,1)=1 */

  INPUT_2BYTES(cinfo, tmp, return FALSE);

  if (tmp != 0) goto bad;			/* A(2,2)=0 */

  INPUT_BYTE(cinfo, tmp, return FALSE);

  if (tmp != 0) goto bad;		/* F3: CENTER3=0, NORM3=0 */

  INPUT_2BYTES(cinfo, tmp, return FALSE);

  if (tmp != 1) goto bad;			/* A(3,1)=1 */

  INPUT_2BYTES(cinfo, tmp, return FALSE);

  if (tmp != 0) {				/* A(3,2)=0 */

    bad:

    ERREXIT(cinfo, JERR_CONVERSION_NOTIMPL);

  }

  /* OK, valid transform that we can handle. */

  cinfo->color_transform = JCT_SUBTRACT_GREEN;

  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, 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.

 */

{

  INT32 totallen = (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 !=

	((INT32)GETJOCTET(data[12]) * (INT32)GETJOCTET(data[13]) * (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, 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 */

{

  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;

  INT32 length = 0;

  INPUT_VARS(cinfo);