ref: bea7b7bf8ccbc2bc41906517079e76fcfb31cb5a
dir: /code/jpeg-6/jdmarker.c/
/*
* jdmarker.c
*
* Copyright (C) 1991-1995, 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 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;
/*
* 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 --- seldom used except 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); \
} \
bytes_in_buffer--
/* 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); \
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); \
V = ((unsigned int) GETJOCTET(*next_input_byte++)) << 8; \
MAKE_BYTE_AVAIL(cinfo,action); \
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,
* but we use skip_input_data to get past those, and thereby put the problem
* on the source manager's shoulders.
*
* 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->density_unit = 0; /* set default JFIF APP0 values */
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 */
{
INT32 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 */
{
INT32 length;
int i, ci, n, c, cc;
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 */
if (length != (n * 2 + 6) || n < 1 || n > MAX_COMPS_IN_SCAN)
ERREXIT(cinfo, JERR_BAD_LENGTH);
TRACEMS1(cinfo, 1, JTRC_SOS, n);
cinfo->comps_in_scan = n;
/* Collect the component-spec parameters */
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++, compptr++) {
if (cc == compptr->component_id)
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);
}
/* 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;
}
METHODDEF boolean
get_app0 (j_decompress_ptr cinfo)
/* Process an APP0 marker */
{
#define JFIF_LEN 14
INT32 length;
UINT8 b[JFIF_LEN];
int buffp;
INPUT_VARS(cinfo);
INPUT_2BYTES(cinfo, length, return FALSE);
length -= 2;
/* See if a JFIF APP0 marker is present */
if (length >= JFIF_LEN) {
for (buffp = 0; buffp < JFIF_LEN; buffp++)
INPUT_BYTE(cinfo, b[buffp], return FALSE);
length -= JFIF_LEN;
if (b[0]==0x4A && b[1]==0x46 && b[2]==0x49 && b[3]==0x46 && b[4]==0) {
/* Found JFIF APP0 marker: 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 (b[5] != 1)
WARNMS2(cinfo, JWRN_JFIF_MAJOR, b[5], b[6]);
else if (b[6] > 2)
TRACEMS2(cinfo, 1, JTRC_JFIF_MINOR, b[5], b[6]);
/* Save info */
cinfo->saw_JFIF_marker = TRUE;
cinfo->density_unit = b[7];
cinfo->X_density = (b[8] << 8) + b[9];
cinfo->Y_density = (b[10] << 8) + b[11];
TRACEMS3(cinfo, 1, JTRC_JFIF,
cinfo->X_density, cinfo->Y_density, cinfo->density_unit);
if (b[12] | b[13])
TRACEMS2(cinfo, 1, JTRC_JFIF_THUMBNAIL, b[12], b[13]);
if (length != ((INT32) b[12] * (INT32) b[13] * (INT32) 3))
TRACEMS1(cinfo, 1, JTRC_JFIF_BADTHUMBNAILSIZE, (int) length);
} else {
/* Start of APP0 does not match "JFIF" */
TRACEMS1(cinfo, 1, JTRC_APP0, (int) length + JFIF_LEN);
}
} else {
/* Too short to be JFIF marker */
TRACEMS1(cinfo, 1, JTRC_APP0, (int) length);
}
INPUT_SYNC(cinfo);
if (length > 0) /* skip any remaining data -- could be lots */
(*cinfo->src->skip_input_data) (cinfo, (long) length);
return TRUE;
}
METHODDEF boolean
get_app14 (j_decompress_ptr cinfo)
/* Process an APP14 marker */
{
#define ADOBE_LEN 12
INT32 length;
UINT8 b[ADOBE_LEN];
int buffp;
unsigned int version, flags0, flags1, transform;
INPUT_VARS(cinfo);
INPUT_2BYTES(cinfo, length, return FALSE);
length -= 2;
/* See if an Adobe APP14 marker is present */
if (length >= ADOBE_LEN) {
for (buffp = 0; buffp < ADOBE_LEN; buffp++)
INPUT_BYTE(cinfo, b[buffp], return FALSE);
length -= ADOBE_LEN;
if (b[0]==0x41 && b[1]==0x64 && b[2]==0x6F && b[3]==0x62 && b[4]==0x65) {
/* Found Adobe APP14 marker */
version = (b[5] << 8) + b[6];
flags0 = (b[7] << 8) + b[8];
flags1 = (b[9] << 8) + b[10];
transform = b[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" */
TRACEMS1(cinfo, 1, JTRC_APP14, (int) length + ADOBE_LEN);
}
} else {
/* Too short to be Adobe marker */
TRACEMS1(cinfo, 1, JTRC_APP14, (int) length);
}
INPUT_SYNC(cinfo);
if (length > 0) /* skip any remaining data -- could be lots */
(*cinfo->src->skip_input_data) (cinfo, (long) length);
return TRUE;
}
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);
}
}
INPUT_SYNC(cinfo);
return TRUE;
}
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 > 0) {
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]);
if (count > 256 || ((INT32) count) > length)
ERREXIT(cinfo, JERR_DHT_COUNTS);
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));
}
INPUT_SYNC(cinfo);
return TRUE;
}
LOCAL boolean
get_dqt (j_decompress_ptr cinfo)
/* Process a DQT marker */
{
INT32 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);
quant_ptr->quantval[i] = (UINT16) tmp;
}
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;
}
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;
}
METHODDEF boolean
skip_variable (j_decompress_ptr cinfo)
/* Skip over an unknown or uninteresting variable-length marker */
{
INT32 length;
INPUT_VARS(cinfo);
INPUT_2BYTES(cinfo, length, return FALSE);
TRACEMS2(cinfo, 1, JTRC_MISC_MARKER, cinfo->unread_marker, (int) length);
INPUT_SYNC(cinfo); /* do before skip_input_data */
(*cinfo->src->skip_input_data) (cinfo, (long) length - 2L);
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 (! (*cinfo->marker->process_APPn[cinfo->unread_marker - (int) M_APP0]) (cinfo))
return JPEG_SUSPENDED;
break;
case M_COM:
if (! (*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, 2, 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)
{
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 */
cinfo->marker->saw_SOI = FALSE; /* set internal state too */
cinfo->marker->saw_SOF = FALSE;
cinfo->marker->discarded_bytes = 0;
}
/*
* 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)
{
int i;
/* Create subobject in permanent pool */
cinfo->marker = (struct jpeg_marker_reader *)
(*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_PERMANENT,
SIZEOF(struct jpeg_marker_reader));
/* Initialize method pointers */
cinfo->marker->reset_marker_reader = reset_marker_reader;
cinfo->marker->read_markers = read_markers;
cinfo->marker->read_restart_marker = read_restart_marker;
cinfo->marker->process_COM = skip_variable;
for (i = 0; i < 16; i++)
cinfo->marker->process_APPn[i] = skip_variable;
cinfo->marker->process_APPn[0] = get_app0;
cinfo->marker->process_APPn[14] = get_app14;
/* Reset marker processing state */
reset_marker_reader(cinfo);
}