ref: f7a16b5e2cc38aed7985b0144bb2655d14ea6f5a
dir: /sys/src/cmd/gs/jpeg/jcmarker.c/
/*
* 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;
}