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author | Matt A. Tobin <mattatobin@localhost.localdomain> | 2018-02-02 04:16:08 -0500 |
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committer | Matt A. Tobin <mattatobin@localhost.localdomain> | 2018-02-02 04:16:08 -0500 |
commit | 5f8de423f190bbb79a62f804151bc24824fa32d8 (patch) | |
tree | 10027f336435511475e392454359edea8e25895d /media/libvpx/vp8/decoder/dboolhuff.h | |
parent | 49ee0794b5d912db1f95dce6eb52d781dc210db5 (diff) | |
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Add m-esr52 at 52.6.0
Diffstat (limited to 'media/libvpx/vp8/decoder/dboolhuff.h')
-rw-r--r-- | media/libvpx/vp8/decoder/dboolhuff.h | 141 |
1 files changed, 141 insertions, 0 deletions
diff --git a/media/libvpx/vp8/decoder/dboolhuff.h b/media/libvpx/vp8/decoder/dboolhuff.h new file mode 100644 index 000000000..51c5adc28 --- /dev/null +++ b/media/libvpx/vp8/decoder/dboolhuff.h @@ -0,0 +1,141 @@ +/* + * Copyright (c) 2010 The WebM project authors. All Rights Reserved. + * + * Use of this source code is governed by a BSD-style license + * that can be found in the LICENSE file in the root of the source + * tree. An additional intellectual property rights grant can be found + * in the file PATENTS. All contributing project authors may + * be found in the AUTHORS file in the root of the source tree. + */ + + +#ifndef VP8_DECODER_DBOOLHUFF_H_ +#define VP8_DECODER_DBOOLHUFF_H_ + +#include <stddef.h> +#include <limits.h> + +#include "vpx_config.h" +#include "vpx_ports/mem.h" +#include "vpx/vp8dx.h" +#include "vpx/vpx_integer.h" + +#ifdef __cplusplus +extern "C" { +#endif + +typedef size_t VP8_BD_VALUE; + +#define VP8_BD_VALUE_SIZE ((int)sizeof(VP8_BD_VALUE)*CHAR_BIT) + +/*This is meant to be a large, positive constant that can still be efficiently + loaded as an immediate (on platforms like ARM, for example). + Even relatively modest values like 100 would work fine.*/ +#define VP8_LOTS_OF_BITS (0x40000000) + +typedef struct +{ + const unsigned char *user_buffer_end; + const unsigned char *user_buffer; + VP8_BD_VALUE value; + int count; + unsigned int range; + vpx_decrypt_cb decrypt_cb; + void *decrypt_state; +} BOOL_DECODER; + +DECLARE_ALIGNED(16, extern const unsigned char, vp8_norm[256]); + +int vp8dx_start_decode(BOOL_DECODER *br, + const unsigned char *source, + unsigned int source_sz, + vpx_decrypt_cb decrypt_cb, + void *decrypt_state); + +void vp8dx_bool_decoder_fill(BOOL_DECODER *br); + + +static int vp8dx_decode_bool(BOOL_DECODER *br, int probability) { + unsigned int bit = 0; + VP8_BD_VALUE value; + unsigned int split; + VP8_BD_VALUE bigsplit; + int count; + unsigned int range; + + split = 1 + (((br->range - 1) * probability) >> 8); + + if(br->count < 0) + vp8dx_bool_decoder_fill(br); + + value = br->value; + count = br->count; + + bigsplit = (VP8_BD_VALUE)split << (VP8_BD_VALUE_SIZE - 8); + + range = split; + + if (value >= bigsplit) + { + range = br->range - split; + value = value - bigsplit; + bit = 1; + } + + { + register unsigned int shift = vp8_norm[range]; + range <<= shift; + value <<= shift; + count -= shift; + } + br->value = value; + br->count = count; + br->range = range; + + return bit; +} + +static int vp8_decode_value(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; +} + +static int vp8dx_bool_error(BOOL_DECODER *br) +{ + /* Check if we have reached the end of the buffer. + * + * Variable 'count' stores the number of bits in the 'value' buffer, minus + * 8. The top byte is part of the algorithm, and the remainder is buffered + * to be shifted into it. So if count == 8, the top 16 bits of 'value' are + * occupied, 8 for the algorithm and 8 in the buffer. + * + * When reading a byte from the user's buffer, count is filled with 8 and + * one byte is filled into the value buffer. When we reach the end of the + * data, count is additionally filled with VP8_LOTS_OF_BITS. So when + * count == VP8_LOTS_OF_BITS - 1, the user's data has been exhausted. + */ + if ((br->count > VP8_BD_VALUE_SIZE) && (br->count < VP8_LOTS_OF_BITS)) + { + /* We have tried to decode bits after the end of + * stream was encountered. + */ + return 1; + } + + /* No error. */ + return 0; +} + +#ifdef __cplusplus +} // extern "C" +#endif + +#endif // VP8_DECODER_DBOOLHUFF_H_ |