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#include <stdlib.h>
#include <stdio.h>
#include "config.h"
#include "morecfg.h"
#include "jpeglib.h"
#include "jpegint.h"
#include "c_huffman.h"
/* 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;
/* Working state while writing an MCU.
* 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;
/* Outputting bytes to the file */
/* Emit a byte, taking 'action' if must suspend. */
#define emit_byte(state,val,action) \
{ *(state)->next_output_byte++ = (JOCTET) (val); \
if (--(state)->free_in_buffer == 0) \
if (! dump_buffer(state)) \
{ action; } }
/* Empty the output buffer; return TRUE if successful, FALSE if must suspend */
static boolean dump_buffer(working_state * state) {
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;
}
/* 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.
*/
/* Emit some bits; return TRUE if successful, FALSE if must suspend */
inline static boolean emit_bits(working_state * state, unsigned int code, int size) {
/* This routine is heavily used, so it's worth coding tightly. */
register INT32 put_buffer = (INT32) code;
register int put_bits = state->cur.put_bits;
/* if size is 0, caller used an invalid Huffman table entry */
if (size == 0) {
perror("Missing Huffman code table entry");
exit(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(state, c, return FALSE);
if (c == 0xFF) { /* need to stuff a zero byte? */
emit_byte(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;
}
int encode_one_block(working_state *state, JCOEFPTR block, int last_dc_val, c_derived_tbl *dctbl, c_derived_tbl *actbl) {
register int temp, temp2;
register int nbits;
register int k, r, i;
/* 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) {
perror("DCT coefficient out of range");
exit(0);
/* ERREXIT(state->cinfo, JERR_BAD_DCT_COEF); */
}
/* Emit the Huffman-coded symbol for the number of bits */
if (! emit_bits(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(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 < DCTSIZE2; k++) {
if ((temp = block[jpeg_natural_order[k]]) == 0) {
r++;
} else {
/* if run length > 15, must emit special run-length-16 codes (0xF0) */
while (r > 15) {
if (! emit_bits(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) {
perror("DCT coefficient out of range");
exit(0);
/* ERREXIT(state->cinfo, JERR_BAD_DCT_COEF); */
}
/* Emit Huffman symbol for run length / number of bits */
i = (r << 4) + nbits;
if (! emit_bits(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(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(state, actbl->ehufco[0], actbl->ehufsi[0])) {
return FALSE;
}
}
return TRUE;
}
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