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