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.
118 lines
3.5 KiB
118 lines
3.5 KiB
/*
|
|
* jchuff.h
|
|
*
|
|
* This file was part of the Independent JPEG Group's software:
|
|
* Copyright (C) 1991-1997, Thomas G. Lane.
|
|
* libjpeg-turbo Modifications:
|
|
* Copyright (C) 2009, 2018, D. R. Commander.
|
|
* Copyright (C) 2018, Matthias Räncker.
|
|
* Copyright (C) 2020-2021, Arm Limited.
|
|
* For conditions of distribution and use, see the accompanying README.ijg
|
|
* file.
|
|
*/
|
|
|
|
/* 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.
|
|
*/
|
|
|
|
#if defined(__aarch64__) || defined(_M_ARM64)
|
|
#define BIT_BUF_SIZE 64
|
|
#else
|
|
#define BIT_BUF_SIZE 32
|
|
#endif
|
|
|
|
typedef struct {
|
|
size_t put_buffer; /* current bit accumulation buffer */
|
|
int free_bits; /* # of bits available in it */
|
|
int last_dc_val[MAX_COMPS_IN_SCAN]; /* last DC coef for each component */
|
|
} savable_state;
|
|
|
|
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 */
|
|
int simd;
|
|
} working_state;
|
|
|
|
/* Outputting bits to the file */
|
|
|
|
/* Output byte b and, speculatively, an additional 0 byte. 0xFF must be encoded
|
|
* as 0xFF 0x00, so the output buffer pointer is advanced by 2 if the byte is
|
|
* 0xFF. Otherwise, the output buffer pointer is advanced by 1, and the
|
|
* speculative 0 byte will be overwritten by the next byte.
|
|
*/
|
|
#define EMIT_BYTE(b) { \
|
|
buffer[0] = (JOCTET)(b); \
|
|
buffer[1] = 0; \
|
|
buffer -= -2 + ((JOCTET)(b) < 0xFF); \
|
|
}
|
|
|
|
/* Output the entire bit buffer. If there are no 0xFF bytes in it, then write
|
|
* directly to the output buffer. Otherwise, use the EMIT_BYTE() macro to
|
|
* encode 0xFF as 0xFF 0x00.
|
|
*/
|
|
#if defined(__aarch64__) || defined(_M_ARM64)
|
|
|
|
#define FLUSH() { \
|
|
if (put_buffer & 0x8080808080808080 & ~(put_buffer + 0x0101010101010101)) { \
|
|
EMIT_BYTE(put_buffer >> 56) \
|
|
EMIT_BYTE(put_buffer >> 48) \
|
|
EMIT_BYTE(put_buffer >> 40) \
|
|
EMIT_BYTE(put_buffer >> 32) \
|
|
EMIT_BYTE(put_buffer >> 24) \
|
|
EMIT_BYTE(put_buffer >> 16) \
|
|
EMIT_BYTE(put_buffer >> 8) \
|
|
EMIT_BYTE(put_buffer ) \
|
|
} else { \
|
|
*((uint64_t *)buffer) = BUILTIN_BSWAP64(put_buffer); \
|
|
buffer += 8; \
|
|
} \
|
|
}
|
|
|
|
#else
|
|
|
|
#define FLUSH() { \
|
|
if (put_buffer & 0x80808080 & ~(put_buffer + 0x01010101)) { \
|
|
EMIT_BYTE(put_buffer >> 24) \
|
|
EMIT_BYTE(put_buffer >> 16) \
|
|
EMIT_BYTE(put_buffer >> 8) \
|
|
EMIT_BYTE(put_buffer ) \
|
|
} else { \
|
|
*((uint32_t *)buffer) = BUILTIN_BSWAP32(put_buffer); \
|
|
buffer += 4; \
|
|
} \
|
|
}
|
|
|
|
#endif
|
|
|
|
/* Fill the bit buffer to capacity with the leading bits from code, then output
|
|
* the bit buffer and put the remaining bits from code into the bit buffer.
|
|
*/
|
|
#define PUT_AND_FLUSH(code, size) { \
|
|
put_buffer = (put_buffer << (size + free_bits)) | (code >> -free_bits); \
|
|
FLUSH() \
|
|
free_bits += BIT_BUF_SIZE; \
|
|
put_buffer = code; \
|
|
}
|
|
|
|
/* Insert code into the bit buffer and output the bit buffer if needed.
|
|
* NOTE: We can't flush with free_bits == 0, since the left shift in
|
|
* PUT_AND_FLUSH() would have undefined behavior.
|
|
*/
|
|
#define PUT_BITS(code, size) { \
|
|
free_bits -= size; \
|
|
if (free_bits < 0) \
|
|
PUT_AND_FLUSH(code, size) \
|
|
else \
|
|
put_buffer = (put_buffer << size) | code; \
|
|
}
|
|
|
|
#define PUT_CODE(code, size, diff) { \
|
|
diff |= code << nbits; \
|
|
nbits += size; \
|
|
PUT_BITS(diff, nbits) \
|
|
}
|