/*
 * jdmarker.c
 *
 * This file was part of the Independent JPEG Group's software:
 * Copyright (C) 1991-1998, Thomas G. Lane.
 * libjpeg-turbo Modifications:
 * Copyright (C) 2012, 2015, D. R. Commander.
 * For conditions of distribution and use, see the accompanying README.ijg
 * 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 JLONG.
 */
#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 */
{
	JLONG 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 */
{
	JLONG length;
	int i, ci, n, c, cc, pi;
	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 < MAX_COMPS_IN_SCAN; i++)
		cinfo->cur_comp_info[i] = NULL;

	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 < MAX_COMPS_IN_SCAN;
		     ci++, compptr++) {
			if (cc == compptr->component_id && !cinfo->cur_comp_info[ci])
				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);

		/* This CSi (cc) should differ from the previous CSi */
		for (pi = 0; pi < i; pi++) {
			if (cinfo->cur_comp_info[pi] == compptr) {
				ERREXIT1(cinfo, JERR_BAD_COMPONENT_ID, cc);
			}
		}
	}

	/* 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 */
{
  JLONG 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 */
{
	JLONG 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 || ((JLONG) count) > length)
			ERREXIT(cinfo, JERR_BAD_HUFF_TABLE);

		for (i = 0; i < count; i++)
			INPUT_BYTE(cinfo, huffval[i], return FALSE);

		MEMZERO(&huffval[count], (256 - count) * sizeof(UINT8));

		length -= count;

		if (index & 0x10) {         /* AC table definition */
			index -= 0x10;
			if (index < 0 || index >= NUM_HUFF_TBLS)
				ERREXIT1(cinfo, JERR_DHT_INDEX, index);
			htblptr = &cinfo->ac_huff_tbl_ptrs[index];
		} else {                    /* DC table definition */
			if (index < 0 || index >= NUM_HUFF_TBLS)
				ERREXIT1(cinfo, JERR_DHT_INDEX, index);
			htblptr = &cinfo->dc_huff_tbl_ptrs[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 */
{
	JLONG 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 */
{
	JLONG 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 *data,
             unsigned int datalen, JLONG 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.
 */
{
	JLONG totallen = (JLONG) 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 !=
		    ((JLONG) GETJOCTET(data[12]) * (JLONG) GETJOCTET(data[13]) * (JLONG) 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 *data,
              unsigned int datalen, JLONG 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 */
{
	JLONG 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 *) b, numtoread, length);
			break;
		case M_APP14:
			examine_app14(cinfo, (JOCTET *) 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 *data;
	JLONG 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 *) (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 */
{
	JLONG 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);
}
