d4708
/
source-engine
mirror of https://github.com/nillerusr/source-engine.git
1
0
Fork 0
Code Issues Projects Releases Wiki Activity
Modified source engine (2017) developed by valve and leaked in 2020. Not for commercial purporses
You can not select more than 25 topics Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
14 Commits
25 Branches
6 Tags
221 MiB
Tree: 3fec7d612e
Branches Tags
${ item.name }
Create tag ${ searchTerm }
Create branch ${ searchTerm }
from '3fec7d612e'
${ noResults }
source-engine/utils/jpeglib/jchuff.c

1577 lines
47 KiB
Raw Normal View History Unescape

1
5 years ago
/*
* jchuff.c
*
* Copyright (C) 1991-1997, Thomas G. Lane.
* Modified 2006-2009 by Guido Vollbeding.
* 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 Huffman entropy encoding routines.
* Both sequential and progressive modes are supported in this single module.
*
* Much of the complexity here has to do with supporting output suspension.
* If the data destination module demands suspension, we want to be able to
* back up to the start of the current MCU. To do this, we copy state
* variables into local working storage, and update them back to the
* permanent JPEG objects only upon successful completion of an MCU.
*
* We do not support output suspension for the progressive JPEG mode, since
* the library currently does not allow multiple-scan files to be written
* with output suspension.
*/
#define JPEG_INTERNALS
#include "jinclude.h"
#include "jpeglib.h"
/* The legal range of a DCT coefficient is
* -1024 .. +1023 for 8-bit data;
* -16384 .. +16383 for 12-bit data.
* Hence the magnitude should always fit in 10 or 14 bits respectively.
*/
#if BITS_IN_JSAMPLE == 8
#define MAX_COEF_BITS 10
#else
#define MAX_COEF_BITS 14
#endif
/* Derived data constructed for each Huffman table */
typedef struct {
unsigned int ehufco[256]; /* code for each symbol */
char ehufsi[256]; /* length of code for each symbol */
/* If no code has been allocated for a symbol S, ehufsi[S] contains 0 */
} c_derived_tbl;
/* Expanded entropy encoder object for Huffman encoding.
*
* The savable_state subrecord contains fields that change within an MCU,
* but must not be updated permanently until we complete the MCU.
*/
typedef struct {
INT32 put_buffer; /* current bit-accumulation buffer */
int put_bits; /* # of bits now in it */
int last_dc_val[MAX_COMPS_IN_SCAN]; /* last DC coef for each component */
} savable_state;
/* This macro is to work around compilers with missing or broken
* structure assignment. You'll need to fix this code if you have
* such a compiler and you change MAX_COMPS_IN_SCAN.
*/
#ifndef NO_STRUCT_ASSIGN
#define ASSIGN_STATE(dest,src) ((dest) = (src))
#else
#if MAX_COMPS_IN_SCAN == 4
#define ASSIGN_STATE(dest,src) \
((dest).put_buffer = (src).put_buffer, \
(dest).put_bits = (src).put_bits, \
(dest).last_dc_val[0] = (src).last_dc_val[0], \
(dest).last_dc_val[1] = (src).last_dc_val[1], \
(dest).last_dc_val[2] = (src).last_dc_val[2], \
(dest).last_dc_val[3] = (src).last_dc_val[3])
#endif
#endif
typedef struct {
struct jpeg_entropy_encoder pub; /* public fields */
savable_state saved; /* Bit buffer & DC state at start of MCU */
/* These fields are NOT loaded into local working state. */
unsigned int restarts_to_go; /* MCUs left in this restart interval */
int next_restart_num; /* next restart number to write (0-7) */
/* Pointers to derived tables (these workspaces have image lifespan) */
c_derived_tbl * dc_derived_tbls[NUM_HUFF_TBLS];
c_derived_tbl * ac_derived_tbls[NUM_HUFF_TBLS];
/* Statistics tables for optimization */
long * dc_count_ptrs[NUM_HUFF_TBLS];
long * ac_count_ptrs[NUM_HUFF_TBLS];
/* Following fields used only in progressive mode */
/* Mode flag: TRUE for optimization, FALSE for actual data output */
boolean gather_statistics;
/* next_output_byte/free_in_buffer are local copies of cinfo->dest fields.
*/
JOCTET * next_output_byte; /* => next byte to write in buffer */
size_t free_in_buffer; /* # of byte spaces remaining in buffer */
j_compress_ptr cinfo; /* link to cinfo (needed for dump_buffer) */
/* Coding status for AC components */
int ac_tbl_no; /* the table number of the single component */
unsigned int EOBRUN; /* run length of EOBs */
unsigned int BE; /* # of buffered correction bits before MCU */
char * bit_buffer; /* buffer for correction bits (1 per char) */
/* packing correction bits tightly would save some space but cost time... */
} huff_entropy_encoder;
typedef huff_entropy_encoder * huff_entropy_ptr;
/* Working state while writing an MCU (sequential mode).
* This struct contains all the fields that are needed by subroutines.
*/
typedef struct {
JOCTET * next_output_byte; /* => next byte to write in buffer */
size_t free_in_buffer; /* # of byte spaces remaining in buffer */
savable_state cur; /* Current bit buffer & DC state */
j_compress_ptr cinfo; /* dump_buffer needs access to this */
} working_state;
/* MAX_CORR_BITS is the number of bits the AC refinement correction-bit
* buffer can hold. Larger sizes may slightly improve compression, but
* 1000 is already well into the realm of overkill.
* The minimum safe size is 64 bits.
*/
#define MAX_CORR_BITS 1000 /* Max # of correction bits I can buffer */
/* IRIGHT_SHIFT is like RIGHT_SHIFT, but works on int rather than INT32.
* We assume that int right shift is unsigned if INT32 right shift is,
* which should be safe.
*/
#ifdef RIGHT_SHIFT_IS_UNSIGNED
#define ISHIFT_TEMPS int ishift_temp;
#define IRIGHT_SHIFT(x,shft) \
((ishift_temp = (x)) < 0 ? \
(ishift_temp >> (shft)) | ((~0) << (16-(shft))) : \
(ishift_temp >> (shft)))
#else
#define ISHIFT_TEMPS
#define IRIGHT_SHIFT(x,shft) ((x) >> (shft))
#endif
/*
* Compute the derived values for a Huffman table.
* This routine also performs some validation checks on the table.
*/
LOCAL(void)
jpeg_make_c_derived_tbl (j_compress_ptr cinfo, boolean isDC, int tblno,
c_derived_tbl ** pdtbl)
{
JHUFF_TBL *htbl;
c_derived_tbl *dtbl;
int p, i, l, lastp, si, maxsymbol;
char huffsize[257];
unsigned int huffcode[257];
unsigned int code;
/* Note that huffsize[] and huffcode[] are filled in code-length order,
* paralleling the order of the symbols themselves in htbl->huffval[].
*/
/* Find the input Huffman table */
if (tblno < 0 || tblno >= NUM_HUFF_TBLS)
ERREXIT1(cinfo, JERR_NO_HUFF_TABLE, tblno);
htbl =
isDC ? cinfo->dc_huff_tbl_ptrs[tblno] : cinfo->ac_huff_tbl_ptrs[tblno];
if (htbl == NULL)
ERREXIT1(cinfo, JERR_NO_HUFF_TABLE, tblno);
/* Allocate a workspace if we haven't already done so. */
if (*pdtbl == NULL)
*pdtbl = (c_derived_tbl *)
(*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
SIZEOF(c_derived_tbl));
dtbl = *pdtbl;
/* Figure C.1: make table of Huffman code length for each symbol */
p = 0;
for (l = 1; l <= 16; l++) {
i = (int) htbl->bits[l];
if (i < 0 || p + i > 256) /* protect against table overrun */
ERREXIT(cinfo, JERR_BAD_HUFF_TABLE);
while (i--)
huffsize[p++] = (char) l;
}
huffsize[p] = 0;
lastp = p;
/* Figure C.2: generate the codes themselves */
/* We also validate that the counts represent a legal Huffman code tree. */
code = 0;
si = huffsize[0];
p = 0;
while (huffsize[p]) {
while (((int) huffsize[p]) == si) {
huffcode[p++] = code;
code++;
}
/* code is now 1 more than the last code used for codelength si; but
* it must still fit in si bits, since no code is allowed to be all ones.
*/
if (((INT32) code) >= (((INT32) 1) << si))
ERREXIT(cinfo, JERR_BAD_HUFF_TABLE);
code <<= 1;
si++;
}
/* Figure C.3: generate encoding tables */
/* These are code and size indexed by symbol value */
/* Set all codeless symbols to have code length 0;
* this lets us detect duplicate VAL entries here, and later
* allows emit_bits to detect any attempt to emit such symbols.
*/
MEMZERO(dtbl->ehufsi, SIZEOF(dtbl->ehufsi));
/* This is also a convenient place to check for out-of-range
* and duplicated VAL entries. We allow 0..255 for AC symbols
* but only 0..15 for DC. (We could constrain them further
* based on data depth and mode, but this seems enough.)
*/
maxsymbol = isDC ? 15 : 255;
for (p = 0; p < lastp; p++) {
i = htbl->huffval[p];
if (i < 0 || i > maxsymbol || dtbl->ehufsi[i])
ERREXIT(cinfo, JERR_BAD_HUFF_TABLE);
dtbl->ehufco[i] = huffcode[p];
dtbl->ehufsi[i] = huffsize[p];
}
}
/* Outputting bytes to the file.
* NB: these must be called only when actually outputting,
* that is, entropy->gather_statistics == FALSE.
*/
/* Emit a byte, taking 'action' if must suspend. */
#define emit_byte_s(state,val,action) \
{ *(state)->next_output_byte++ = (JOCTET) (val); \
if (--(state)->free_in_buffer == 0) \
if (! dump_buffer_s(state)) \
{ action; } }
/* Emit a byte */
#define emit_byte_e(entropy,val) \
{ *(entropy)->next_output_byte++ = (JOCTET) (val); \
if (--(entropy)->free_in_buffer == 0) \
dump_buffer_e(entropy); }
LOCAL(boolean)
dump_buffer_s (working_state * state)
/* Empty the output buffer; return TRUE if successful, FALSE if must suspend */
{
struct jpeg_destination_mgr * dest = state->cinfo->dest;
if (! (*dest->empty_output_buffer) (state->cinfo))
return FALSE;
/* After a successful buffer dump, must reset buffer pointers */
state->next_output_byte = dest->next_output_byte;
state->free_in_buffer = dest->free_in_buffer;
return TRUE;
}
LOCAL(void)
dump_buffer_e (huff_entropy_ptr entropy)
/* Empty the output buffer; we do not support suspension in this case. */
{
struct jpeg_destination_mgr * dest = entropy->cinfo->dest;
if (! (*dest->empty_output_buffer) (entropy->cinfo))
ERREXIT(entropy->cinfo, JERR_CANT_SUSPEND);
/* After a successful buffer dump, must reset buffer pointers */
entropy->next_output_byte = dest->next_output_byte;
entropy->free_in_buffer = dest->free_in_buffer;
}
/* Outputting bits to the file */
/* Only the right 24 bits of put_buffer are used; the valid bits are
* left-justified in this part. At most 16 bits can be passed to emit_bits
* in one call, and we never retain more than 7 bits in put_buffer
* between calls, so 24 bits are sufficient.
*/
INLINE
LOCAL(boolean)
emit_bits_s (working_state * state, unsigned int code, int size)
/* Emit some bits; return TRUE if successful, FALSE if must suspend */
{
/* This routine is heavily used, so it's worth coding tightly. */
INT32 put_buffer = (INT32) code;
int put_bits = state->cur.put_bits;
/* if size is 0, caller used an invalid Huffman table entry */
if (size == 0)
ERREXIT(state->cinfo, JERR_HUFF_MISSING_CODE);
put_buffer &= (((INT32) 1)<<size) - 1; /* mask off any extra bits in code */
put_bits += size; /* new number of bits in buffer */
put_buffer <<= 24 - put_bits; /* align incoming bits */
put_buffer |= state->cur.put_buffer; /* and merge with old buffer contents */
while (put_bits >= 8) {
int c = (int) ((put_buffer >> 16) & 0xFF);
emit_byte_s(state, c, return FALSE);
if (c == 0xFF) { /* need to stuff a zero byte? */
emit_byte_s(state, 0, return FALSE);
}
put_buffer <<= 8;
put_bits -= 8;
}
state->cur.put_buffer = put_buffer; /* update state variables */
state->cur.put_bits = put_bits;
return TRUE;
}
INLINE
LOCAL(void)
emit_bits_e (huff_entropy_ptr entropy, unsigned int code, int size)
/* Emit some bits, unless we are in gather mode */
{
/* This routine is heavily used, so it's worth coding tightly. */
INT32 put_buffer = (INT32) code;
int put_bits = entropy->saved.put_bits;
/* if size is 0, caller used an invalid Huffman table entry */
if (size == 0)
ERREXIT(entropy->cinfo, JERR_HUFF_MISSING_CODE);
if (entropy->gather_statistics)
return; /* do nothing if we're only getting stats */
put_buffer &= (((INT32) 1)<<size) - 1; /* mask off any extra bits in code */
put_bits += size; /* new number of bits in buffer */
put_buffer <<= 24 - put_bits; /* align incoming bits */
/* and merge with old buffer contents */
put_buffer |= entropy->saved.put_buffer;
while (put_bits >= 8) {
int c = (int) ((put_buffer >> 16) & 0xFF);
emit_byte_e(entropy, c);
if (c == 0xFF) { /* need to stuff a zero byte? */
emit_byte_e(entropy, 0);
}
put_buffer <<= 8;
put_bits -= 8;
}
entropy->saved.put_buffer = put_buffer; /* update variables */
entropy->saved.put_bits = put_bits;
}
LOCAL(boolean)
flush_bits_s (working_state * state)
{
if (! emit_bits_s(state, 0x7F, 7)) /* fill any partial byte with ones */
return FALSE;
state->cur.put_buffer = 0; /* and reset bit-buffer to empty */
state->cur.put_bits = 0;
return TRUE;
}
LOCAL(void)
flush_bits_e (huff_entropy_ptr entropy)
{
emit_bits_e(entropy, 0x7F, 7); /* fill any partial byte with ones */
entropy->saved.put_buffer = 0; /* and reset bit-buffer to empty */
entropy->saved.put_bits = 0;
}
/*
* Emit (or just count) a Huffman symbol.
*/
INLINE
LOCAL(void)
emit_dc_symbol (huff_entropy_ptr entropy, int tbl_no, int symbol)
{
if (entropy->gather_statistics)
entropy->dc_count_ptrs[tbl_no][symbol]++;
else {
c_derived_tbl * tbl = entropy->dc_derived_tbls[tbl_no];
emit_bits_e(entropy, tbl->ehufco[symbol], tbl->ehufsi[symbol]);
}
}
INLINE
LOCAL(void)
emit_ac_symbol (huff_entropy_ptr entropy, int tbl_no, int symbol)
{
if (entropy->gather_statistics)
entropy->ac_count_ptrs[tbl_no][symbol]++;
else {
c_derived_tbl * tbl = entropy->ac_derived_tbls[tbl_no];
emit_bits_e(entropy, tbl->ehufco[symbol], tbl->ehufsi[symbol]);
}
}
/*
* Emit bits from a correction bit buffer.
*/
LOCAL(void)
emit_buffered_bits (huff_entropy_ptr entropy, char * bufstart,
unsigned int nbits)
{
if (entropy->gather_statistics)
return; /* no real work */
while (nbits > 0) {
emit_bits_e(entropy, (unsigned int) (*bufstart), 1);
bufstart++;
nbits--;
}
}
/*
* Emit any pending EOBRUN symbol.
*/
LOCAL(void)
emit_eobrun (huff_entropy_ptr entropy)
{
int temp, nbits;
if (entropy->EOBRUN > 0) { /* if there is any pending EOBRUN */
temp = entropy->EOBRUN;
nbits = 0;
while ((temp >>= 1))
nbits++;
/* safety check: shouldn't happen given limited correction-bit buffer */
if (nbits > 14)
ERREXIT(entropy->cinfo, JERR_HUFF_MISSING_CODE);
emit_ac_symbol(entropy, entropy->ac_tbl_no, nbits << 4);
if (nbits)
emit_bits_e(entropy, entropy->EOBRUN, nbits);
entropy->EOBRUN = 0;
/* Emit any buffered correction bits */
emit_buffered_bits(entropy, entropy->bit_buffer, entropy->BE);
entropy->BE = 0;
}
}
/*
* Emit a restart marker & resynchronize predictions.
*/
LOCAL(boolean)
emit_restart_s (working_state * state, int restart_num)
{
int ci;
if (! flush_bits_s(state))
return FALSE;
emit_byte_s(state, 0xFF, return FALSE);
emit_byte_s(state, JPEG_RST0 + restart_num, return FALSE);
/* Re-initialize DC predictions to 0 */
for (ci = 0; ci < state->cinfo->comps_in_scan; ci++)
state->cur.last_dc_val[ci] = 0;
/* The restart counter is not updated until we successfully write the MCU. */
return TRUE;
}
LOCAL(void)
emit_restart_e (huff_entropy_ptr entropy, int restart_num)
{
int ci;
emit_eobrun(entropy);
if (! entropy->gather_statistics) {
flush_bits_e(entropy);
emit_byte_e(entropy, 0xFF);
emit_byte_e(entropy, JPEG_RST0 + restart_num);
}
if (entropy->cinfo->Ss == 0) {
/* Re-initialize DC predictions to 0 */
for (ci = 0; ci < entropy->cinfo->comps_in_scan; ci++)
entropy->saved.last_dc_val[ci] = 0;
} else {
/* Re-initialize all AC-related fields to 0 */
entropy->EOBRUN = 0;
entropy->BE = 0;
}
}
/*
* MCU encoding for DC initial scan (either spectral selection,
* or first pass of successive approximation).
*/
METHODDEF(boolean)
encode_mcu_DC_first (j_compress_ptr cinfo, JBLOCKROW *MCU_data)
{
huff_entropy_ptr entropy = (huff_entropy_ptr) cinfo->entropy;
int temp, temp2;
int nbits;
int blkn, ci;
int Al = cinfo->Al;
JBLOCKROW block;
jpeg_component_info * compptr;
ISHIFT_TEMPS
entropy->next_output_byte = cinfo->dest->next_output_byte;
entropy->free_in_buffer = cinfo->dest->free_in_buffer;
/* Emit restart marker if needed */
if (cinfo->restart_interval)
if (entropy->restarts_to_go == 0)
emit_restart_e(entropy, entropy->next_restart_num);
/* Encode the MCU data blocks */
for (blkn = 0; blkn < cinfo->blocks_in_MCU; blkn++) {
block = MCU_data[blkn];
ci = cinfo->MCU_membership[blkn];
compptr = cinfo->cur_comp_info[ci];
/* Compute the DC value after the required point transform by Al.
* This is simply an arithmetic right shift.
*/
temp2 = IRIGHT_SHIFT((int) ((*block)[0]), Al);
/* DC differences are figured on the point-transformed values. */
temp = temp2 - entropy->saved.last_dc_val[ci];
entropy->saved.last_dc_val[ci] = temp2;
/* Encode the DC coefficient difference per section G.1.2.1 */
temp2 = temp;
if (temp < 0) {
temp = -temp; /* temp is abs value of input */
/* For a negative input, want temp2 = bitwise complement of abs(input) */
/* This code assumes we are on a two's complement machine */
temp2--;
}
/* Find the number of bits needed for the magnitude of the coefficient */
nbits = 0;
while (temp) {
nbits++;
temp >>= 1;
}
/* Check for out-of-range coefficient values.
* Since we're encoding a difference, the range limit is twice as much.
*/
if (nbits > MAX_COEF_BITS+1)
ERREXIT(cinfo, JERR_BAD_DCT_COEF);
/* Count/emit the Huffman-coded symbol for the number of bits */
emit_dc_symbol(entropy, compptr->dc_tbl_no, nbits);
/* Emit that number of bits of the value, if positive, */
/* or the complement of its magnitude, if negative. */
if (nbits) /* emit_bits rejects calls with size 0 */
emit_bits_e(entropy, (unsigned int) temp2, nbits);
}
cinfo->dest->next_output_byte = entropy->next_output_byte;
cinfo->dest->free_in_buffer = entropy->free_in_buffer;
/* Update restart-interval state too */
if (cinfo->restart_interval) {
if (entropy->restarts_to_go == 0) {
entropy->restarts_to_go = cinfo->restart_interval;
entropy->next_restart_num++;
entropy->next_restart_num &= 7;
}
entropy->restarts_to_go--;
}
return TRUE;
}
/*
* MCU encoding for AC initial scan (either spectral selection,
* or first pass of successive approximation).
*/
METHODDEF(boolean)
encode_mcu_AC_first (j_compress_ptr cinfo, JBLOCKROW *MCU_data)
{
huff_entropy_ptr entropy = (huff_entropy_ptr) cinfo->entropy;
int temp, temp2;
int nbits;
int r, k;
int Se, Al;
const int * natural_order;
JBLOCKROW block;
entropy->next_output_byte = cinfo->dest->next_output_byte;
entropy->free_in_buffer = cinfo->dest->free_in_buffer;
/* Emit restart marker if needed */
if (cinfo->restart_interval)
if (entropy->restarts_to_go == 0)
emit_restart_e(entropy, entropy->next_restart_num);
Se = cinfo->Se;
Al = cinfo->Al;
natural_order = cinfo->natural_order;
/* Encode the MCU data block */
block = MCU_data[0];
/* Encode the AC coefficients per section G.1.2.2, fig. G.3 */
r = 0; /* r = run length of zeros */
for (k = cinfo->Ss; k <= Se; k++) {
if ((temp = (*block)[natural_order[k]]) == 0) {
r++;
continue;
}
/* We must apply the point transform by Al. For AC coefficients this
* is an integer division with rounding towards 0. To do this portably
* in C, we shift after obtaining the absolute value; so the code is
* interwoven with finding the abs value (temp) and output bits (temp2).
*/
if (temp < 0) {
temp = -temp; /* temp is abs value of input */
temp >>= Al; /* apply the point transform */
/* For a negative coef, want temp2 = bitwise complement of abs(coef) */
temp2 = ~temp;
} else {
temp >>= Al; /* apply the point transform */
temp2 = temp;
}
/* Watch out for case that nonzero coef is zero after point transform */
if (temp == 0) {
r++;
continue;
}
/* Emit any pending EOBRUN */
if (entropy->EOBRUN > 0)
emit_eobrun(entropy);
/* if run length > 15, must emit special run-length-16 codes (0xF0) */
while (r > 15) {
emit_ac_symbol(entropy, entropy->ac_tbl_no, 0xF0);
r -= 16;
}
/* Find the number of bits needed for the magnitude of the coefficient */
nbits = 1; /* there must be at least one 1 bit */
while ((temp >>= 1))
nbits++;
/* Check for out-of-range coefficient values */
if (nbits > MAX_COEF_BITS)
ERREXIT(cinfo, JERR_BAD_DCT_COEF);
/* Count/emit Huffman symbol for run length / number of bits */
emit_ac_symbol(entropy, entropy->ac_tbl_no, (r << 4) + nbits);
/* Emit that number of bits of the value, if positive, */
/* or the complement of its magnitude, if negative. */
emit_bits_e(entropy, (unsigned int) temp2, nbits);
r = 0; /* reset zero run length */
}
if (r > 0) { /* If there are trailing zeroes, */
entropy->EOBRUN++; /* count an EOB */
if (entropy->EOBRUN == 0x7FFF)
emit_eobrun(entropy); /* force it out to avoid overflow */
}
cinfo->dest->next_output_byte = entropy->next_output_byte;
cinfo->dest->free_in_buffer = entropy->free_in_buffer;
/* Update restart-interval state too */
if (cinfo->restart_interval) {
if (entropy->restarts_to_go == 0) {
entropy->restarts_to_go = cinfo->restart_interval;
entropy->next_restart_num++;
entropy->next_restart_num &= 7;
}
entropy->restarts_to_go--;
}
return TRUE;
}
/*
* MCU encoding for DC successive approximation refinement scan.
* Note: we assume such scans can be multi-component, although the spec
* is not very clear on the point.
*/
METHODDEF(boolean)
encode_mcu_DC_refine (j_compress_ptr cinfo, JBLOCKROW *MCU_data)
{
huff_entropy_ptr entropy = (huff_entropy_ptr) cinfo->entropy;
int temp;
int blkn;
int Al = cinfo->Al;
JBLOCKROW block;
entropy->next_output_byte = cinfo->dest->next_output_byte;
entropy->free_in_buffer = cinfo->dest->free_in_buffer;
/* Emit restart marker if needed */
if (cinfo->restart_interval)
if (entropy->restarts_to_go == 0)
emit_restart_e(entropy, entropy->next_restart_num);
/* Encode the MCU data blocks */
for (blkn = 0; blkn < cinfo->blocks_in_MCU; blkn++) {
block = MCU_data[blkn];
/* We simply emit the Al'th bit of the DC coefficient value. */
temp = (*block)[0];
emit_bits_e(entropy, (unsigned int) (temp >> Al), 1);
}
cinfo->dest->next_output_byte = entropy->next_output_byte;
cinfo->dest->free_in_buffer = entropy->free_in_buffer;
/* Update restart-interval state too */
if (cinfo->restart_interval) {
if (entropy->restarts_to_go == 0) {
entropy->restarts_to_go = cinfo->restart_interval;
entropy->next_restart_num++;
entropy->next_restart_num &= 7;
}
entropy->restarts_to_go--;
}
return TRUE;
}
/*
* MCU encoding for AC successive approximation refinement scan.
*/
METHODDEF(boolean)
encode_mcu_AC_refine (j_compress_ptr cinfo, JBLOCKROW *MCU_data)
{
huff_entropy_ptr entropy = (huff_entropy_ptr) cinfo->entropy;
int temp;
int r, k;
int EOB;
char *BR_buffer;
unsigned int BR;
int Se, Al;
const int * natural_order;
JBLOCKROW block;
int absvalues[DCTSIZE2];
entropy->next_output_byte = cinfo->dest->next_output_byte;
entropy->free_in_buffer = cinfo->dest->free_in_buffer;
/* Emit restart marker if needed */
if (cinfo->restart_interval)
if (entropy->restarts_to_go == 0)
emit_restart_e(entropy, entropy->next_restart_num);
Se = cinfo->Se;
Al = cinfo->Al;
natural_order = cinfo->natural_order;
/* Encode the MCU data block */
block = MCU_data[0];
/* It is convenient to make a pre-pass to determine the transformed
* coefficients' absolute values and the EOB position.
*/
EOB = 0;
for (k = cinfo->Ss; k <= Se; k++) {
temp = (*block)[natural_order[k]];
/* We must apply the point transform by Al. For AC coefficients this
* is an integer division with rounding towards 0. To do this portably
* in C, we shift after obtaining the absolute value.
*/
if (temp < 0)
temp = -temp; /* temp is abs value of input */
temp >>= Al; /* apply the point transform */
absvalues[k] = temp; /* save abs value for main pass */
if (temp == 1)
EOB = k; /* EOB = index of last newly-nonzero coef */
}
/* Encode the AC coefficients per section G.1.2.3, fig. G.7 */
r = 0; /* r = run length of zeros */
BR = 0; /* BR = count of buffered bits added now */
BR_buffer = entropy->bit_buffer + entropy->BE; /* Append bits to buffer */
for (k = cinfo->Ss; k <= Se; k++) {
if ((temp = absvalues[k]) == 0) {
r++;
continue;
}
/* Emit any required ZRLs, but not if they can be folded into EOB */
while (r > 15 && k <= EOB) {
/* emit any pending EOBRUN and the BE correction bits */
emit_eobrun(entropy);
/* Emit ZRL */
emit_ac_symbol(entropy, entropy->ac_tbl_no, 0xF0);
r -= 16;
/* Emit buffered correction bits that must be associated with ZRL */
emit_buffered_bits(entropy, BR_buffer, BR);
BR_buffer = entropy->bit_buffer; /* BE bits are gone now */
BR = 0;
}
/* If the coef was previously nonzero, it only needs a correction bit.
* NOTE: a straight translation of the spec's figure G.7 would suggest
* that we also need to test r > 15. But if r > 15, we can only get here
* if k > EOB, which implies that this coefficient is not 1.
*/
if (temp > 1) {
/* The correction bit is the next bit of the absolute value. */
BR_buffer[BR++] = (char) (temp & 1);
continue;
}
/* Emit any pending EOBRUN and the BE correction bits */
emit_eobrun(entropy);
/* Count/emit Huffman symbol for run length / number of bits */
emit_ac_symbol(entropy, entropy->ac_tbl_no, (r << 4) + 1);
/* Emit output bit for newly-nonzero coef */
temp = ((*block)[natural_order[k]] < 0) ? 0 : 1;
emit_bits_e(entropy, (unsigned int) temp, 1);
/* Emit buffered correction bits that must be associated with this code */
emit_buffered_bits(entropy, BR_buffer, BR);
BR_buffer = entropy->bit_buffer; /* BE bits are gone now */
BR = 0;
r = 0; /* reset zero run length */
}
if (r > 0 || BR > 0) { /* If there are trailing zeroes, */
entropy->EOBRUN++; /* count an EOB */
entropy->BE += BR; /* concat my correction bits to older ones */
/* We force out the EOB if we risk either:
* 1. overflow of the EOB counter;
* 2. overflow of the correction bit buffer during the next MCU.
*/
if (entropy->EOBRUN == 0x7FFF || entropy->BE > (MAX_CORR_BITS-DCTSIZE2+1))
emit_eobrun(entropy);
}
cinfo->dest->next_output_byte = entropy->next_output_byte;
cinfo->dest->free_in_buffer = entropy->free_in_buffer;
/* Update restart-interval state too */
if (cinfo->restart_interval) {
if (entropy->restarts_to_go == 0) {
entropy->restarts_to_go = cinfo->restart_interval;
entropy->next_restart_num++;
entropy->next_restart_num &= 7;
}
entropy->restarts_to_go--;
}
return TRUE;
}
/* Encode a single block's worth of coefficients */
LOCAL(boolean)
encode_one_block (working_state * state, JCOEFPTR block, int last_dc_val,
c_derived_tbl *dctbl, c_derived_tbl *actbl)
{
int temp, temp2;
int nbits;
int k, r, i;
int Se = state->cinfo->lim_Se;
const int * natural_order = state->cinfo->natural_order;
/* Encode the DC coefficient difference per section F.1.2.1 */
temp = temp2 = block[0] - last_dc_val;
if (temp < 0) {
temp = -temp; /* temp is abs value of input */
/* For a negative input, want temp2 = bitwise complement of abs(input) */
/* This code assumes we are on a two's complement machine */
temp2--;
}
/* Find the number of bits needed for the magnitude of the coefficient */
nbits = 0;
while (temp) {
nbits++;
temp >>= 1;
}
/* Check for out-of-range coefficient values.
* Since we're encoding a difference, the range limit is twice as much.
*/
if (nbits > MAX_COEF_BITS+1)
ERREXIT(state->cinfo, JERR_BAD_DCT_COEF);
/* Emit the Huffman-coded symbol for the number of bits */
if (! emit_bits_s(state, dctbl->ehufco[nbits], dctbl->ehufsi[nbits]))
return FALSE;
/* Emit that number of bits of the value, if positive, */
/* or the complement of its magnitude, if negative. */
if (nbits) /* emit_bits rejects calls with size 0 */
if (! emit_bits_s(state, (unsigned int) temp2, nbits))
return FALSE;
/* Encode the AC coefficients per section F.1.2.2 */
r = 0; /* r = run length of zeros */
for (k = 1; k <= Se; k++) {
if ((temp = block[natural_order[k]]) == 0) {
r++;
} else {
/* if run length > 15, must emit special run-length-16 codes (0xF0) */
while (r > 15) {
if (! emit_bits_s(state, actbl->ehufco[0xF0], actbl->ehufsi[0xF0]))
return FALSE;
r -= 16;
}
temp2 = temp;
if (temp < 0) {
temp = -temp; /* temp is abs value of input */
/* This code assumes we are on a two's complement machine */
temp2--;
}
/* Find the number of bits needed for the magnitude of the coefficient */
nbits = 1; /* there must be at least one 1 bit */
while ((temp >>= 1))
nbits++;
/* Check for out-of-range coefficient values */
if (nbits > MAX_COEF_BITS)
ERREXIT(state->cinfo, JERR_BAD_DCT_COEF);
/* Emit Huffman symbol for run length / number of bits */
i = (r << 4) + nbits;
if (! emit_bits_s(state, actbl->ehufco[i], actbl->ehufsi[i]))
return FALSE;
/* Emit that number of bits of the value, if positive, */
/* or the complement of its magnitude, if negative. */
if (! emit_bits_s(state, (unsigned int) temp2, nbits))
return FALSE;
r = 0;
}
}
/* If the last coef(s) were zero, emit an end-of-block code */
if (r > 0)
if (! emit_bits_s(state, actbl->ehufco[0], actbl->ehufsi[0]))
return FALSE;
return TRUE;
}
/*
* Encode and output one MCU's worth of Huffman-compressed coefficients.
*/
METHODDEF(boolean)
encode_mcu_huff (j_compress_ptr cinfo, JBLOCKROW *MCU_data)
{
huff_entropy_ptr entropy = (huff_entropy_ptr) cinfo->entropy;
working_state state;
int blkn, ci;
jpeg_component_info * compptr;
/* Load up working state */
state.next_output_byte = cinfo->dest->next_output_byte;
state.free_in_buffer = cinfo->dest->free_in_buffer;
ASSIGN_STATE(state.cur, entropy->saved);
state.cinfo = cinfo;
/* Emit restart marker if needed */
if (cinfo->restart_interval) {
if (entropy->restarts_to_go == 0)
if (! emit_restart_s(&state, entropy->next_restart_num))
return FALSE;
}
/* Encode the MCU data blocks */
for (blkn = 0; blkn < cinfo->blocks_in_MCU; blkn++) {
ci = cinfo->MCU_membership[blkn];
compptr = cinfo->cur_comp_info[ci];
if (! encode_one_block(&state,
MCU_data[blkn][0], state.cur.last_dc_val[ci],
entropy->dc_derived_tbls[compptr->dc_tbl_no],
entropy->ac_derived_tbls[compptr->ac_tbl_no]))
return FALSE;
/* Update last_dc_val */
state.cur.last_dc_val[ci] = MCU_data[blkn][0][0];
}
/* Completed MCU, so update state */
cinfo->dest->next_output_byte = state.next_output_byte;
cinfo->dest->free_in_buffer = state.free_in_buffer;
ASSIGN_STATE(entropy->saved, state.cur);
/* Update restart-interval state too */
if (cinfo->restart_interval) {
if (entropy->restarts_to_go == 0) {
entropy->restarts_to_go = cinfo->restart_interval;
entropy->next_restart_num++;
entropy->next_restart_num &= 7;
}
entropy->restarts_to_go--;
}
return TRUE;
}
/*
* Finish up at the end of a Huffman-compressed scan.
*/
METHODDEF(void)
finish_pass_huff (j_compress_ptr cinfo)
{
huff_entropy_ptr entropy = (huff_entropy_ptr) cinfo->entropy;
working_state state;
if (cinfo->progressive_mode) {
entropy->next_output_byte = cinfo->dest->next_output_byte;
entropy->free_in_buffer = cinfo->dest->free_in_buffer;
/* Flush out any buffered data */
emit_eobrun(entropy);
flush_bits_e(entropy);
cinfo->dest->next_output_byte = entropy->next_output_byte;
cinfo->dest->free_in_buffer = entropy->free_in_buffer;
} else {
/* Load up working state ... flush_bits needs it */
state.next_output_byte = cinfo->dest->next_output_byte;
state.free_in_buffer = cinfo->dest->free_in_buffer;
ASSIGN_STATE(state.cur, entropy->saved);
state.cinfo = cinfo;
/* Flush out the last data */
if (! flush_bits_s(&state))
ERREXIT(cinfo, JERR_CANT_SUSPEND);
/* Update state */
cinfo->dest->next_output_byte = state.next_output_byte;
cinfo->dest->free_in_buffer = state.free_in_buffer;
ASSIGN_STATE(entropy->saved, state.cur);
}
}
/*
* Huffman coding optimization.
*
* We first scan the supplied data and count the number of uses of each symbol
* that is to be Huffman-coded. (This process MUST agree with the code above.)
* Then we build a Huffman coding tree for the observed counts.
* Symbols which are not needed at all for the particular image are not
* assigned any code, which saves space in the DHT marker as well as in
* the compressed data.
*/
/* Process a single block's worth of coefficients */
LOCAL(void)
htest_one_block (j_compress_ptr cinfo, JCOEFPTR block, int last_dc_val,
long dc_counts[], long ac_counts[])
{
int temp;
int nbits;
int k, r;
int Se = cinfo->lim_Se;
const int * natural_order = cinfo->natural_order;
/* Encode the DC coefficient difference per section F.1.2.1 */
temp = block[0] - last_dc_val;
if (temp < 0)
temp = -temp;
/* Find the number of bits needed for the magnitude of the coefficient */
nbits = 0;
while (temp) {
nbits++;
temp >>= 1;
}
/* Check for out-of-range coefficient values.
* Since we're encoding a difference, the range limit is twice as much.
*/
if (nbits > MAX_COEF_BITS+1)
ERREXIT(cinfo, JERR_BAD_DCT_COEF);
/* Count the Huffman symbol for the number of bits */
dc_counts[nbits]++;
/* Encode the AC coefficients per section F.1.2.2 */
r = 0; /* r = run length of zeros */
for (k = 1; k <= Se; k++) {
if ((temp = block[natural_order[k]]) == 0) {
r++;
} else {
/* if run length > 15, must emit special run-length-16 codes (0xF0) */
while (r > 15) {
ac_counts[0xF0]++;
r -= 16;
}
/* Find the number of bits needed for the magnitude of the coefficient */
if (temp < 0)
temp = -temp;
/* Find the number of bits needed for the magnitude of the coefficient */
nbits = 1; /* there must be at least one 1 bit */
while ((temp >>= 1))
nbits++;
/* Check for out-of-range coefficient values */
if (nbits > MAX_COEF_BITS)
ERREXIT(cinfo, JERR_BAD_DCT_COEF);
/* Count Huffman symbol for run length / number of bits */
ac_counts[(r << 4) + nbits]++;
r = 0;
}
}
/* If the last coef(s) were zero, emit an end-of-block code */
if (r > 0)
ac_counts[0]++;
}
/*
* Trial-encode one MCU's worth of Huffman-compressed coefficients.
* No data is actually output, so no suspension return is possible.
*/
METHODDEF(boolean)
encode_mcu_gather (j_compress_ptr cinfo, JBLOCKROW *MCU_data)
{
huff_entropy_ptr entropy = (huff_entropy_ptr) cinfo->entropy;
int blkn, ci;
jpeg_component_info * compptr;
/* Take care of restart intervals if needed */
if (cinfo->restart_interval) {
if (entropy->restarts_to_go == 0) {
/* Re-initialize DC predictions to 0 */
for (ci = 0; ci < cinfo->comps_in_scan; ci++)
entropy->saved.last_dc_val[ci] = 0;
/* Update restart state */
entropy->restarts_to_go = cinfo->restart_interval;
}
entropy->restarts_to_go--;
}
for (blkn = 0; blkn < cinfo->blocks_in_MCU; blkn++) {
ci = cinfo->MCU_membership[blkn];
compptr = cinfo->cur_comp_info[ci];
htest_one_block(cinfo, MCU_data[blkn][0], entropy->saved.last_dc_val[ci],
entropy->dc_count_ptrs[compptr->dc_tbl_no],
entropy->ac_count_ptrs[compptr->ac_tbl_no]);
entropy->saved.last_dc_val[ci] = MCU_data[blkn][0][0];
}
return TRUE;
}
/*
* Generate the best Huffman code table for the given counts, fill htbl.
*
* The JPEG standard requires that no symbol be assigned a codeword of all
* one bits (so that padding bits added at the end of a compressed segment
* can't look like a valid code). Because of the canonical ordering of
* codewords, this just means that there must be an unused slot in the
* longest codeword length category. Section K.2 of the JPEG spec suggests
* reserving such a slot by pretending that symbol 256 is a valid symbol
* with count 1. In theory that's not optimal; giving it count zero but
* including it in the symbol set anyway should give a better Huffman code.
* But the theoretically better code actually seems to come out worse in
* practice, because it produces more all-ones bytes (which incur stuffed
* zero bytes in the final file). In any case the difference is tiny.
*
* The JPEG standard requires Huffman codes to be no more than 16 bits long.
* If some symbols have a very small but nonzero probability, the Huffman tree
* must be adjusted to meet the code length restriction. We currently use
* the adjustment method suggested in JPEG section K.2. This method is *not*
* optimal; it may not choose the best possible limited-length code. But
* typically only very-low-frequency symbols will be given less-than-optimal
* lengths, so the code is almost optimal. Experimental comparisons against
* an optimal limited-length-code algorithm indicate that the difference is
* microscopic --- usually less than a hundredth of a percent of total size.
* So the extra complexity of an optimal algorithm doesn't seem worthwhile.
*/
LOCAL(void)
jpeg_gen_optimal_table (j_compress_ptr cinfo, JHUFF_TBL * htbl, long freq[])
{
#define MAX_CLEN 32 /* assumed maximum initial code length */
UINT8 bits[MAX_CLEN+1]; /* bits[k] = # of symbols with code length k */
int codesize[257]; /* codesize[k] = code length of symbol k */
int others[257]; /* next symbol in current branch of tree */
int c1, c2;
int p, i, j;
long v;
/* This algorithm is explained in section K.2 of the JPEG standard */
MEMZERO(bits, SIZEOF(bits));
MEMZERO(codesize, SIZEOF(codesize));
for (i = 0; i < 257; i++)
others[i] = -1; /* init links to empty */
freq[256] = 1; /* make sure 256 has a nonzero count */
/* Including the pseudo-symbol 256 in the Huffman procedure guarantees
* that no real symbol is given code-value of all ones, because 256
* will be placed last in the largest codeword category.
*/
/* Huffman's basic algorithm to assign optimal code lengths to symbols */
for (;;) {
/* Find the smallest nonzero frequency, set c1 = its symbol */
/* In case of ties, take the larger symbol number */
c1 = -1;
v = 1000000000L;
for (i = 0; i <= 256; i++) {
if (freq[i] && freq[i] <= v) {
v = freq[i];
c1 = i;
}
}
/* Find the next smallest nonzero frequency, set c2 = its symbol */
/* In case of ties, take the larger symbol number */
c2 = -1;
v = 1000000000L;
for (i = 0; i <= 256; i++) {
if (freq[i] && freq[i] <= v && i != c1) {
v = freq[i];
c2 = i;
}
}
/* Done if we've merged everything into one frequency */
if (c2 < 0)
break;
/* Else merge the two counts/trees */
freq[c1] += freq[c2];
freq[c2] = 0;
/* Increment the codesize of everything in c1's tree branch */
codesize[c1]++;
while (others[c1] >= 0) {
c1 = others[c1];
codesize[c1]++;
}
others[c1] = c2; /* chain c2 onto c1's tree branch */
/* Increment the codesize of everything in c2's tree branch */
codesize[c2]++;
while (others[c2] >= 0) {
c2 = others[c2];
codesize[c2]++;
}
}
/* Now count the number of symbols of each code length */
for (i = 0; i <= 256; i++) {
if (codesize[i]) {
/* The JPEG standard seems to think that this can't happen, */
/* but I'm paranoid... */
if (codesize[i] > MAX_CLEN)
ERREXIT(cinfo, JERR_HUFF_CLEN_OVERFLOW);
bits[codesize[i]]++;
}
}
/* JPEG doesn't allow symbols with code lengths over 16 bits, so if the pure
* Huffman procedure assigned any such lengths, we must adjust the coding.
* Here is what the JPEG spec says about how this next bit works:
* Since symbols are paired for the longest Huffman code, the symbols are
* removed from this length category two at a time. The prefix for the pair
* (which is one bit shorter) is allocated to one of the pair; then,
* skipping the BITS entry for that prefix length, a code word from the next
* shortest nonzero BITS entry is converted into a prefix for two code words
* one bit longer.
*/
for (i = MAX_CLEN; i > 16; i--) {
while (bits[i] > 0) {
j = i - 2; /* find length of new prefix to be used */
while (bits[j] == 0)
j--;
bits[i] -= 2; /* remove two symbols */
bits[i-1]++; /* one goes in this length */
bits[j+1] += 2; /* two new symbols in this length */
bits[j]--; /* symbol of this length is now a prefix */
}
}
/* Remove the count for the pseudo-symbol 256 from the largest codelength */
while (bits[i] == 0) /* find largest codelength still in use */
i--;
bits[i]--;
/* Return final symbol counts (only for lengths 0..16) */
MEMCOPY(htbl->bits, bits, SIZEOF(htbl->bits));
/* Return a list of the symbols sorted by code length */
/* It's not real clear to me why we don't need to consider the codelength
* changes made above, but the JPEG spec seems to think this works.
*/
p = 0;
for (i = 1; i <= MAX_CLEN; i++) {
for (j = 0; j <= 255; j++) {
if (codesize[j] == i) {
htbl->huffval[p] = (UINT8) j;
p++;
}
}
}
/* Set sent_table FALSE so updated table will be written to JPEG file. */
htbl->sent_table = FALSE;
}
/*
* Finish up a statistics-gathering pass and create the new Huffman tables.
*/
METHODDEF(void)
finish_pass_gather (j_compress_ptr cinfo)
{
huff_entropy_ptr entropy = (huff_entropy_ptr) cinfo->entropy;
int ci, tbl;
jpeg_component_info * compptr;
JHUFF_TBL **htblptr;
boolean did_dc[NUM_HUFF_TBLS];
boolean did_ac[NUM_HUFF_TBLS];
/* It's important not to apply jpeg_gen_optimal_table more than once
* per table, because it clobbers the input frequency counts!
*/
if (cinfo->progressive_mode)
/* Flush out buffered data (all we care about is counting the EOB symbol) */
emit_eobrun(entropy);
MEMZERO(did_dc, SIZEOF(did_dc));
MEMZERO(did_ac, SIZEOF(did_ac));
for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
compptr = cinfo->cur_comp_info[ci];
/* DC needs no table for refinement scan */
if (cinfo->Ss == 0 && cinfo->Ah == 0) {
tbl = compptr->dc_tbl_no;
if (! did_dc[tbl]) {
htblptr = & cinfo->dc_huff_tbl_ptrs[tbl];
if (*htblptr == NULL)
*htblptr = jpeg_alloc_huff_table((j_common_ptr) cinfo);
jpeg_gen_optimal_table(cinfo, *htblptr, entropy->dc_count_ptrs[tbl]);
did_dc[tbl] = TRUE;
}
}
/* AC needs no table when not present */
if (cinfo->Se) {
tbl = compptr->ac_tbl_no;
if (! did_ac[tbl]) {
htblptr = & cinfo->ac_huff_tbl_ptrs[tbl];
if (*htblptr == NULL)
*htblptr = jpeg_alloc_huff_table((j_common_ptr) cinfo);
jpeg_gen_optimal_table(cinfo, *htblptr, entropy->ac_count_ptrs[tbl]);
did_ac[tbl] = TRUE;
}
}
}
}
/*
* Initialize for a Huffman-compressed scan.
* If gather_statistics is TRUE, we do not output anything during the scan,
* just count the Huffman symbols used and generate Huffman code tables.
*/
METHODDEF(void)
start_pass_huff (j_compress_ptr cinfo, boolean gather_statistics)
{
huff_entropy_ptr entropy = (huff_entropy_ptr) cinfo->entropy;
int ci, tbl;
jpeg_component_info * compptr;
if (gather_statistics)
entropy->pub.finish_pass = finish_pass_gather;
else
entropy->pub.finish_pass = finish_pass_huff;
if (cinfo->progressive_mode) {
entropy->cinfo = cinfo;
entropy->gather_statistics = gather_statistics;
/* We assume jcmaster.c already validated the scan parameters. */
/* Select execution routine */
if (cinfo->Ah == 0) {
if (cinfo->Ss == 0)
entropy->pub.encode_mcu = encode_mcu_DC_first;
else
entropy->pub.encode_mcu = encode_mcu_AC_first;
} else {
if (cinfo->Ss == 0)
entropy->pub.encode_mcu = encode_mcu_DC_refine;
else {
entropy->pub.encode_mcu = encode_mcu_AC_refine;
/* AC refinement needs a correction bit buffer */
if (entropy->bit_buffer == NULL)
entropy->bit_buffer = (char *)
(*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
MAX_CORR_BITS * SIZEOF(char));
}
}
/* Initialize AC stuff */
entropy->ac_tbl_no = cinfo->cur_comp_info[0]->ac_tbl_no;
entropy->EOBRUN = 0;
entropy->BE = 0;
} else {
if (gather_statistics)
entropy->pub.encode_mcu = encode_mcu_gather;
else
entropy->pub.encode_mcu = encode_mcu_huff;
}
for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
compptr = cinfo->cur_comp_info[ci];
/* DC needs no table for refinement scan */
if (cinfo->Ss == 0 && cinfo->Ah == 0) {
tbl = compptr->dc_tbl_no;
if (gather_statistics) {
/* Check for invalid table index */
/* (make_c_derived_tbl does this in the other path) */
if (tbl < 0 || tbl >= NUM_HUFF_TBLS)
ERREXIT1(cinfo, JERR_NO_HUFF_TABLE, tbl);
/* Allocate and zero the statistics tables */
/* Note that jpeg_gen_optimal_table expects 257 entries in each table! */
if (entropy->dc_count_ptrs[tbl] == NULL)
entropy->dc_count_ptrs[tbl] = (long *)
(*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
257 * SIZEOF(long));
MEMZERO(entropy->dc_count_ptrs[tbl], 257 * SIZEOF(long));
} else {
/* Compute derived values for Huffman tables */
/* We may do this more than once for a table, but it's not expensive */
jpeg_make_c_derived_tbl(cinfo, TRUE, tbl,
& entropy->dc_derived_tbls[tbl]);
}
/* Initialize DC predictions to 0 */
entropy->saved.last_dc_val[ci] = 0;
}
/* AC needs no table when not present */
if (cinfo->Se) {
tbl = compptr->ac_tbl_no;
if (gather_statistics) {
if (tbl < 0 || tbl >= NUM_HUFF_TBLS)
ERREXIT1(cinfo, JERR_NO_HUFF_TABLE, tbl);
if (entropy->ac_count_ptrs[tbl] == NULL)
entropy->ac_count_ptrs[tbl] = (long *)
(*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
257 * SIZEOF(long));
MEMZERO(entropy->ac_count_ptrs[tbl], 257 * SIZEOF(long));
} else {
jpeg_make_c_derived_tbl(cinfo, FALSE, tbl,
& entropy->ac_derived_tbls[tbl]);
}
}
}
/* Initialize bit buffer to empty */
entropy->saved.put_buffer = 0;
entropy->saved.put_bits = 0;
/* Initialize restart stuff */
entropy->restarts_to_go = cinfo->restart_interval;
entropy->next_restart_num = 0;
}
/*
* Module initialization routine for Huffman entropy encoding.
*/
GLOBAL(void)
jinit_huff_encoder (j_compress_ptr cinfo)
{
huff_entropy_ptr entropy;
int i;
entropy = (huff_entropy_ptr)
(*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
SIZEOF(huff_entropy_encoder));
cinfo->entropy = (struct jpeg_entropy_encoder *) entropy;
entropy->pub.start_pass = start_pass_huff;
/* Mark tables unallocated */
for (i = 0; i < NUM_HUFF_TBLS; i++) {
entropy->dc_derived_tbls[i] = entropy->ac_derived_tbls[i] = NULL;
entropy->dc_count_ptrs[i] = entropy->ac_count_ptrs[i] = NULL;
}
if (cinfo->progressive_mode)
entropy->bit_buffer = NULL; /* needed only in AC refinement scan */
}