jcmarker.c
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jcmarker.c
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	/*
	* jcmarker.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 write JPEG datastream markers.
	*/

	#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_writer pub; /* public fields */

	unsigned int last_restart_interval; /* last DRI value emitted; 0 after SOI */
	} my_marker_writer;

	typedef my_marker_writer * my_marker_ptr;


	/*
	* Basic output routines.
	*
	* Note that we do not support suspension while writing a marker.
	* Therefore, an application using suspension must ensure that there is
	* enough buffer space for the initial markers (typ. 600-700 bytes) before
	* calling jpeg_start_compress, and enough space to write the trailing EOI
	* (a few bytes) before calling jpeg_finish_compress. Multipass compression
	* modes are not supported at all with suspension, so those two are the only
	* points where markers will be written.
	*/

	LOCAL(void)
	emit_byte (j_compress_ptr cinfo, int val)
	/* Emit a byte */
	{
	struct jpeg_destination_mgr * dest = cinfo->dest;

	*(dest->next_output_byte)++ = (JOCTET) val;
	if (--dest->free_in_buffer == 0) {
	if (! (*dest->empty_output_buffer) (cinfo))
	ERREXIT(cinfo, JERR_CANT_SUSPEND);
	}
	}


	LOCAL(void)
	emit_marker (j_compress_ptr cinfo, JPEG_MARKER mark)
	/* Emit a marker code */
	{
	emit_byte(cinfo, 0xFF);
	emit_byte(cinfo, (int) mark);
	}


	LOCAL(void)
	emit_2bytes (j_compress_ptr cinfo, int value)
	/* Emit a 2-byte integer; these are always MSB first in JPEG files */
	{
	emit_byte(cinfo, (value >> 8) & 0xFF);
	emit_byte(cinfo, value & 0xFF);
	}


	/*
	* Routines to write specific marker types.
	*/

	LOCAL(int)
	emit_dqt (j_compress_ptr cinfo, int index)
	/* Emit a DQT marker */
	/* Returns the precision used (0 = 8bits, 1 = 16bits) for baseline checking */
	{
	JQUANT_TBL * qtbl = cinfo->quant_tbl_ptrs[index];
	int prec;
	int i;

	if (qtbl == NULL)
	ERREXIT1(cinfo, JERR_NO_QUANT_TABLE, index);

	prec = 0;
	for (i = 0; i < DCTSIZE2; i++) {
	if (qtbl->quantval[i] > 255)
	prec = 1;
	}

	if (! qtbl->sent_table) {
	emit_marker(cinfo, M_DQT);

	emit_2bytes(cinfo, prec ? DCTSIZE2*2 + 1 + 2 : DCTSIZE2 + 1 + 2);

	emit_byte(cinfo, index + (prec<<4));

	for (i = 0; i < DCTSIZE2; i++) {
	/* The table entries must be emitted in zigzag order. */
	unsigned int qval = qtbl->quantval[jpeg_natural_order[i]];
	if (prec)
	emit_byte(cinfo, (int) (qval >> 8));
	emit_byte(cinfo, (int) (qval & 0xFF));
	}

	qtbl->sent_table = TRUE;
	}

	return prec;
	}


	LOCAL(void)
	emit_dht (j_compress_ptr cinfo, int index, boolean is_ac)
	/* Emit a DHT marker */
	{
	JHUFF_TBL * htbl;
	int length, i;

	if (is_ac) {
	htbl = cinfo->ac_huff_tbl_ptrs[index];
	index += 0x10; /* output index has AC bit set */
	} else {
	htbl = cinfo->dc_huff_tbl_ptrs[index];
	}

	if (htbl == NULL)
	ERREXIT1(cinfo, JERR_NO_HUFF_TABLE, index);

	if (! htbl->sent_table) {
	emit_marker(cinfo, M_DHT);

	length = 0;
	for (i = 1; i <= 16; i++)
	length += htbl->bits[i];

	emit_2bytes(cinfo, length + 2 + 1 + 16);
	emit_byte(cinfo, index);

	for (i = 1; i <= 16; i++)
	emit_byte(cinfo, htbl->bits[i]);

	for (i = 0; i < length; i++)
	emit_byte(cinfo, htbl->huffval[i]);

	htbl->sent_table = TRUE;
	}
	}


	LOCAL(void)
	emit_dac (j_compress_ptr cinfo)
	/* Emit a DAC marker */
	/* Since the useful info is so small, we want to emit all the tables in */
	/* one DAC marker. Therefore this routine does its own scan of the table. */
	{
	#ifdef C_ARITH_CODING_SUPPORTED
	char dc_in_use[NUM_ARITH_TBLS];
	char ac_in_use[NUM_ARITH_TBLS];
	int length, i;
	jpeg_component_info *compptr;

	for (i = 0; i < NUM_ARITH_TBLS; i++)
	dc_in_use[i] = ac_in_use[i] = 0;

	for (i = 0; i < cinfo->comps_in_scan; i++) {
	compptr = cinfo->cur_comp_info[i];
	dc_in_use[compptr->dc_tbl_no] = 1;
	ac_in_use[compptr->ac_tbl_no] = 1;
	}

	length = 0;
	for (i = 0; i < NUM_ARITH_TBLS; i++)
	length += dc_in_use[i] + ac_in_use[i];

	emit_marker(cinfo, M_DAC);

	emit_2bytes(cinfo, length*2 + 2);

	for (i = 0; i < NUM_ARITH_TBLS; i++) {
	if (dc_in_use[i]) {
	emit_byte(cinfo, i);
	emit_byte(cinfo, cinfo->arith_dc_L[i] + (cinfo->arith_dc_U[i]<<4));
	}
	if (ac_in_use[i]) {
	emit_byte(cinfo, i + 0x10);
	emit_byte(cinfo, cinfo->arith_ac_K[i]);
	}
	}
	#endif /* C_ARITH_CODING_SUPPORTED */
	}


	LOCAL(void)
	emit_dri (j_compress_ptr cinfo)
	/* Emit a DRI marker */
	{
	emit_marker(cinfo, M_DRI);

	emit_2bytes(cinfo, 4); /* fixed length */

	emit_2bytes(cinfo, (int) cinfo->restart_interval);
	}


	LOCAL(void)
	emit_sof (j_compress_ptr cinfo, JPEG_MARKER code)
	/* Emit a SOF marker */
	{
	int ci;
	jpeg_component_info *compptr;

	emit_marker(cinfo, code);

	emit_2bytes(cinfo, 3 * cinfo->num_components + 2 + 5 + 1); /* length */

	/* Make sure image isn't bigger than SOF field can handle */
	if ((long) cinfo->image_height > 65535L \|\|
	(long) cinfo->image_width > 65535L)
	ERREXIT1(cinfo, JERR_IMAGE_TOO_BIG, (unsigned int) 65535);

	emit_byte(cinfo, cinfo->data_precision);
	emit_2bytes(cinfo, (int) cinfo->image_height);
	emit_2bytes(cinfo, (int) cinfo->image_width);

	emit_byte(cinfo, cinfo->num_components);

	for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
	ci++, compptr++) {
	emit_byte(cinfo, compptr->component_id);
	emit_byte(cinfo, (compptr->h_samp_factor << 4) + compptr->v_samp_factor);
	emit_byte(cinfo, compptr->quant_tbl_no);
	}
	}


	LOCAL(void)
	emit_sos (j_compress_ptr cinfo)
	/* Emit a SOS marker */
	{
	int i, td, ta;
	jpeg_component_info *compptr;

	emit_marker(cinfo, M_SOS);

	emit_2bytes(cinfo, 2 * cinfo->comps_in_scan + 2 + 1 + 3); /* length */

	emit_byte(cinfo, cinfo->comps_in_scan);

	for (i = 0; i < cinfo->comps_in_scan; i++) {
	compptr = cinfo->cur_comp_info[i];
	emit_byte(cinfo, compptr->component_id);
	td = compptr->dc_tbl_no;
	ta = compptr->ac_tbl_no;
	if (cinfo->progressive_mode) {
	/* Progressive mode: only DC or only AC tables are used in one scan;
	* furthermore, Huffman coding of DC refinement uses no table at all.
	* We emit 0 for unused field(s); this is recommended by the P&M text
	* but does not seem to be specified in the standard.
	*/
	if (cinfo->Ss == 0) {
	ta = 0; /* DC scan */
	if (cinfo->Ah != 0 && !cinfo->arith_code)
	td = 0; /* no DC table either */
	} else {
	td = 0; /* AC scan */
	}
	}
	emit_byte(cinfo, (td << 4) + ta);
	}

	emit_byte(cinfo, cinfo->Ss);
	emit_byte(cinfo, cinfo->Se);
	emit_byte(cinfo, (cinfo->Ah << 4) + cinfo->Al);
	}


	LOCAL(void)
	emit_jfif_app0 (j_compress_ptr cinfo)
	/* Emit a JFIF-compliant APP0 marker */
	{
	/*
	* Length of APP0 block (2 bytes)
	* Block ID (4 bytes - ASCII "JFIF")
	* Zero byte (1 byte to terminate the ID string)
	* Version Major, Minor (2 bytes - major first)
	* Units (1 byte - 0x00 = none, 0x01 = inch, 0x02 = cm)
	* Xdpu (2 bytes - dots per unit horizontal)
	* Ydpu (2 bytes - dots per unit vertical)
	* Thumbnail X size (1 byte)
	* Thumbnail Y size (1 byte)
	*/

	emit_marker(cinfo, M_APP0);

	emit_2bytes(cinfo, 2 + 4 + 1 + 2 + 1 + 2 + 2 + 1 + 1); /* length */

	emit_byte(cinfo, 0x4A); /* Identifier: ASCII "JFIF" */
	emit_byte(cinfo, 0x46);
	emit_byte(cinfo, 0x49);
	emit_byte(cinfo, 0x46);
	emit_byte(cinfo, 0);
	emit_byte(cinfo, cinfo->JFIF_major_version); /* Version fields */
	emit_byte(cinfo, cinfo->JFIF_minor_version);
	emit_byte(cinfo, cinfo->density_unit); /* Pixel size information */
	emit_2bytes(cinfo, (int) cinfo->X_density);
	emit_2bytes(cinfo, (int) cinfo->Y_density);
	emit_byte(cinfo, 0); /* No thumbnail image */
	emit_byte(cinfo, 0);
	}


	LOCAL(void)
	emit_adobe_app14 (j_compress_ptr cinfo)
	/* Emit an Adobe APP14 marker */
	{
	/*
	* Length of APP14 block (2 bytes)
	* Block ID (5 bytes - ASCII "Adobe")
	* Version Number (2 bytes - currently 100)
	* Flags0 (2 bytes - currently 0)
	* Flags1 (2 bytes - currently 0)
	* Color transform (1 byte)
	*
	* Although Adobe TN 5116 mentions Version = 101, all the Adobe files
	* now in circulation seem to use Version = 100, so that's what we write.
	*
	* We write the color transform byte as 1 if the JPEG color space is
	* YCbCr, 2 if it's YCCK, 0 otherwise. Adobe's definition has to do with
	* whether the encoder performed a transformation, which is pretty useless.
	*/

	emit_marker(cinfo, M_APP14);

	emit_2bytes(cinfo, 2 + 5 + 2 + 2 + 2 + 1); /* length */

	emit_byte(cinfo, 0x41); /* Identifier: ASCII "Adobe" */
	emit_byte(cinfo, 0x64);
	emit_byte(cinfo, 0x6F);
	emit_byte(cinfo, 0x62);
	emit_byte(cinfo, 0x65);
	emit_2bytes(cinfo, 100); /* Version */
	emit_2bytes(cinfo, 0); /* Flags0 */
	emit_2bytes(cinfo, 0); /* Flags1 */
	switch (cinfo->jpeg_color_space) {
	case JCS_YCbCr:
	emit_byte(cinfo, 1); /* Color transform = 1 */
	break;
	case JCS_YCCK:
	emit_byte(cinfo, 2); /* Color transform = 2 */
	break;
	default:
	emit_byte(cinfo, 0); /* Color transform = 0 */
	break;
	}
	}


	/*
	* These routines allow writing an arbitrary marker with parameters.
	* The only intended use is to emit COM or APPn markers after calling
	* write_file_header and before calling write_frame_header.
	* Other uses are not guaranteed to produce desirable results.
	* Counting the parameter bytes properly is the caller's responsibility.
	*/

	METHODDEF(void)
	write_marker_header (j_compress_ptr cinfo, int marker, unsigned int datalen)
	/* Emit an arbitrary marker header */
	{
	if (datalen > (unsigned int) 65533) /* safety check */
	ERREXIT(cinfo, JERR_BAD_LENGTH);

	emit_marker(cinfo, (JPEG_MARKER) marker);

	emit_2bytes(cinfo, (int) (datalen + 2)); /* total length */
	}

	METHODDEF(void)
	write_marker_byte (j_compress_ptr cinfo, int val)
	/* Emit one byte of marker parameters following write_marker_header */
	{
	emit_byte(cinfo, val);
	}


	/*
	* Write datastream header.
	* This consists of an SOI and optional APPn markers.
	* We recommend use of the JFIF marker, but not the Adobe marker,
	* when using YCbCr or grayscale data. The JFIF marker should NOT
	* be used for any other JPEG colorspace. The Adobe marker is helpful
	* to distinguish RGB, CMYK, and YCCK colorspaces.
	* Note that an application can write additional header markers after
	* jpeg_start_compress returns.
	*/

	METHODDEF(void)
	write_file_header (j_compress_ptr cinfo)
	{
	my_marker_ptr marker = (my_marker_ptr) cinfo->marker;

	emit_marker(cinfo, M_SOI); /* first the SOI */

	/* SOI is defined to reset restart interval to 0 */
	marker->last_restart_interval = 0;

	if (cinfo->write_JFIF_header) /* next an optional JFIF APP0 */
	emit_jfif_app0(cinfo);
	if (cinfo->write_Adobe_marker) /* next an optional Adobe APP14 */
	emit_adobe_app14(cinfo);
	}


	/*
	* Write frame header.
	* This consists of DQT and SOFn markers.
	* Note that we do not emit the SOF until we have emitted the DQT(s).
	* This avoids compatibility problems with incorrect implementations that
	* try to error-check the quant table numbers as soon as they see the SOF.
	*/

	METHODDEF(void)
	write_frame_header (j_compress_ptr cinfo)
	{
	int ci, prec;
	boolean is_baseline;
	jpeg_component_info *compptr;

	/* Emit DQT for each quantization table.
	* Note that emit_dqt() suppresses any duplicate tables.
	*/
	prec = 0;
	for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
	ci++, compptr++) {
	prec += emit_dqt(cinfo, compptr->quant_tbl_no);
	}
	/* now prec is nonzero iff there are any 16-bit quant tables. */

	/* Check for a non-baseline specification.
	* Note we assume that Huffman table numbers won't be changed later.
	*/
	if (cinfo->arith_code \|\| cinfo->progressive_mode \|\|
	cinfo->data_precision != 8) {
	is_baseline = FALSE;
	} else {
	is_baseline = TRUE;
	for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
	ci++, compptr++) {
	if (compptr->dc_tbl_no > 1 \|\| compptr->ac_tbl_no > 1)
	is_baseline = FALSE;
	}
	if (prec && is_baseline) {
	is_baseline = FALSE;
	/* If it's baseline except for quantizer size, warn the user */
	TRACEMS(cinfo, 0, JTRC_16BIT_TABLES);
	}
	}

	/* Emit the proper SOF marker */
	if (cinfo->arith_code) {
	emit_sof(cinfo, M_SOF9); /* SOF code for arithmetic coding */
	} else {
	if (cinfo->progressive_mode)
	emit_sof(cinfo, M_SOF2); /* SOF code for progressive Huffman */
	else if (is_baseline)
	emit_sof(cinfo, M_SOF0); /* SOF code for baseline implementation */
	else
	emit_sof(cinfo, M_SOF1); /* SOF code for non-baseline Huffman file */
	}
	}


	/*
	* Write scan header.
	* This consists of DHT or DAC markers, optional DRI, and SOS.
	* Compressed data will be written following the SOS.
	*/

	METHODDEF(void)
	write_scan_header (j_compress_ptr cinfo)
	{
	my_marker_ptr marker = (my_marker_ptr) cinfo->marker;
	int i;
	jpeg_component_info *compptr;

	if (cinfo->arith_code) {
	/* Emit arith conditioning info. We may have some duplication
	* if the file has multiple scans, but it's so small it's hardly
	* worth worrying about.
	*/
	emit_dac(cinfo);
	} else {
	/* Emit Huffman tables.
	* Note that emit_dht() suppresses any duplicate tables.
	*/
	for (i = 0; i < cinfo->comps_in_scan; i++) {
	compptr = cinfo->cur_comp_info[i];
	if (cinfo->progressive_mode) {
	/* Progressive mode: only DC or only AC tables are used in one scan */
	if (cinfo->Ss == 0) {
	if (cinfo->Ah == 0) /* DC needs no table for refinement scan */
	emit_dht(cinfo, compptr->dc_tbl_no, FALSE);
	} else {
	emit_dht(cinfo, compptr->ac_tbl_no, TRUE);
	}
	} else {
	/* Sequential mode: need both DC and AC tables */
	emit_dht(cinfo, compptr->dc_tbl_no, FALSE);
	emit_dht(cinfo, compptr->ac_tbl_no, TRUE);
	}
	}
	}

	/* Emit DRI if required --- note that DRI value could change for each scan.
	* We avoid wasting space with unnecessary DRIs, however.
	*/
	if (cinfo->restart_interval != marker->last_restart_interval) {
	emit_dri(cinfo);
	marker->last_restart_interval = cinfo->restart_interval;
	}

	emit_sos(cinfo);
	}


	/*
	* Write datastream trailer.
	*/

	METHODDEF(void)
	write_file_trailer (j_compress_ptr cinfo)
	{
	emit_marker(cinfo, M_EOI);
	}


	/*
	* Write an abbreviated table-specification datastream.
	* This consists of SOI, DQT and DHT tables, and EOI.
	* Any table that is defined and not marked sent_table = TRUE will be
	* emitted. Note that all tables will be marked sent_table = TRUE at exit.
	*/

	METHODDEF(void)
	write_tables_only (j_compress_ptr cinfo)
	{
	int i;

	emit_marker(cinfo, M_SOI);

	for (i = 0; i < NUM_QUANT_TBLS; i++) {
	if (cinfo->quant_tbl_ptrs[i] != NULL)
	(void) emit_dqt(cinfo, i);
	}

	if (! cinfo->arith_code) {
	for (i = 0; i < NUM_HUFF_TBLS; i++) {
	if (cinfo->dc_huff_tbl_ptrs[i] != NULL)
	emit_dht(cinfo, i, FALSE);
	if (cinfo->ac_huff_tbl_ptrs[i] != NULL)
	emit_dht(cinfo, i, TRUE);
	}
	}

	emit_marker(cinfo, M_EOI);
	}


	/*
	* Initialize the marker writer module.
	*/

	GLOBAL(void)
	jinit_marker_writer (j_compress_ptr cinfo)
	{
	my_marker_ptr marker;

	/* Create the subobject */
	marker = (my_marker_ptr)
	(*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
	SIZEOF(my_marker_writer));
	cinfo->marker = (struct jpeg_marker_writer *) marker;
	/* Initialize method pointers */
	marker->pub.write_file_header = write_file_header;
	marker->pub.write_frame_header = write_frame_header;
	marker->pub.write_scan_header = write_scan_header;
	marker->pub.write_file_trailer = write_file_trailer;
	marker->pub.write_tables_only = write_tables_only;
	marker->pub.write_marker_header = write_marker_header;
	marker->pub.write_marker_byte = write_marker_byte;
	/* Initialize private state */
	marker->last_restart_interval = 0;
	}

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