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1 line
15 KiB
C
1 line
15 KiB
C
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/*
* jcmarker.c
*
* Copyright (C) 1991-1994, 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;
/*
* 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++) {
if (prec)
emit_byte(cinfo, qtbl->quantval[i] >> 8);
emit_byte(cinfo, qtbl->quantval[i] & 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
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