diff options
Diffstat (limited to 'vp8/decoder/dboolhuff.c')
| -rw-r--r-- | vp8/decoder/dboolhuff.c | 174 |
1 files changed, 174 insertions, 0 deletions
diff --git a/vp8/decoder/dboolhuff.c b/vp8/decoder/dboolhuff.c new file mode 100644 index 000000000..442054ed3 --- /dev/null +++ b/vp8/decoder/dboolhuff.c @@ -0,0 +1,174 @@ +/* + * Copyright (c) 2010 The VP8 project authors. All Rights Reserved. + * + * Use of this source code is governed by a BSD-style license and patent + * grant that can be found in the LICENSE file in the root of the source + * tree. All contributing project authors may be found in the AUTHORS + * file in the root of the source tree. + */ + + +#include "dboolhuff.h" +#include "vpx_ports/mem.h" +#include "vpx_mem/vpx_mem.h" + +DECLARE_ALIGNED(16, const unsigned int, vp8dx_bitreader_norm[256]) = +{ + 0, 7, 6, 6, 5, 5, 5, 5, 4, 4, 4, 4, 4, 4, 4, 4, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, + 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, + 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, + 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, + 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, + 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, + 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, + 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 +}; + + +static void copy_in(BOOL_DECODER *br, unsigned int to_write) +{ + if (to_write > br->user_buffer_sz) + to_write = br->user_buffer_sz; + + memcpy(br->write_ptr, br->user_buffer, to_write); + br->user_buffer += to_write; + br->user_buffer_sz -= to_write; + br->write_ptr = br_ptr_advance(br->write_ptr, to_write); +} + +int vp8dx_start_decode_c(BOOL_DECODER *br, const unsigned char *source, + unsigned int source_sz) +{ + br->lowvalue = 0; + br->range = 255; + br->count = 0; + br->user_buffer = source; + br->user_buffer_sz = source_sz; + + if (source_sz && !source) + return 1; + + /* Allocate the ring buffer backing store with alignment equal to the + * buffer size*2 so that a single pointer can be used for wrapping rather + * than a pointer+offset. + */ + br->decode_buffer = vpx_memalign(VP8_BOOL_DECODER_SZ * 2, + VP8_BOOL_DECODER_SZ); + + if (!br->decode_buffer) + return 1; + + /* Populate the buffer */ + br->read_ptr = br->decode_buffer; + br->write_ptr = br->decode_buffer; + copy_in(br, VP8_BOOL_DECODER_SZ); + + /* Read the first byte */ + br->value = (*br->read_ptr++) << 8; + return 0; +} + + +void vp8dx_bool_decoder_fill_c(BOOL_DECODER *br) +{ + int left, right; + + /* Find available room in the buffer */ + left = 0; + right = br->read_ptr - br->write_ptr; + + if (right < 0) + { + /* Read pointer is behind the write pointer. We can write from the + * write pointer to the end of the buffer. + */ + right = VP8_BOOL_DECODER_SZ - (br->write_ptr - br->decode_buffer); + left = br->read_ptr - br->decode_buffer; + } + + if (right + left < 128) + return; + + if (right) + copy_in(br, right); + + if (left) + { + br->write_ptr = br->decode_buffer; + copy_in(br, left); + } + +} + + +void vp8dx_stop_decode_c(BOOL_DECODER *bc) +{ + vpx_free(bc->decode_buffer); + bc->decode_buffer = 0; +} + +#if 0 +/* + * Until optimized versions of these functions are available, we + * keep the implementation in the header to allow inlining. + * + * The RTCD-style invocations are still in place so this can + * be switched by just uncommenting these functions here and + * the DBOOLHUFF_INVOKE calls in the header. + */ +int vp8dx_decode_bool_c(BOOL_DECODER *br, int probability) +{ + unsigned int bit=0; + unsigned int split; + unsigned int bigsplit; + register unsigned int range = br->range; + register unsigned int value = br->value; + + split = 1 + (((range-1) * probability) >> 8); + bigsplit = (split<<8); + + range = split; + if(value >= bigsplit) + { + range = br->range-split; + value = value-bigsplit; + bit = 1; + } + + /*if(range>=0x80) + { + br->value = value; + br->range = range; + return bit; + }*/ + + { + int count = br->count; + register unsigned int shift = vp8dx_bitreader_norm[range]; + range <<= shift; + value <<= shift; + count -= shift; + if(count <= 0) + { + value |= (*br->read_ptr) << (-count); + br->read_ptr = br_ptr_advance(br->read_ptr, 1); + count += 8 ; + } + br->count = count; + } + br->value = value; + br->range = range; + return bit; +} + +int vp8dx_decode_value_c(BOOL_DECODER *br, int bits) +{ + int z = 0; + int bit; + for ( bit=bits-1; bit>=0; bit-- ) + { + z |= (vp8dx_decode_bool(br, 0x80)<<bit); + } + return z; +} +#endif |