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87 lines
2.3 KiB
87 lines
2.3 KiB
/****************************************************************************** |
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* |
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* Copyright (C) 2014 The Android Open Source Project |
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* Copyright 2003 - 2004 Open Interface North America, Inc. All rights |
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* reserved. |
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* |
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* Licensed under the Apache License, Version 2.0 (the "License"); |
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* you may not use this file except in compliance with the License. |
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* You may obtain a copy of the License at: |
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* |
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* http://www.apache.org/licenses/LICENSE-2.0 |
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* |
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* Unless required by applicable law or agreed to in writing, software |
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* distributed under the License is distributed on an "AS IS" BASIS, |
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
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* See the License for the specific language governing permissions and |
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* limitations under the License. |
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* |
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******************************************************************************/ |
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/******************************************************************************* |
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$Revision: #1 $ |
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******************************************************************************/ |
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/** |
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@file |
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Functions for manipulating input bitstreams. |
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@ingroup codec_internal |
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*/ |
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/** |
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@addtogroup codec_internal |
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@{ |
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*/ |
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#include "oi_assert.h" |
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#include "oi_bitstream.h" |
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#include "oi_stddefs.h" |
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PRIVATE void OI_BITSTREAM_ReadInit(OI_BITSTREAM* bs, const OI_BYTE* buffer) { |
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bs->value = |
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((int32_t)buffer[0] << 16) | ((int32_t)buffer[1] << 8) | (buffer[2]); |
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bs->ptr.r = buffer + 3; |
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bs->bitPtr = 8; |
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} |
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PRIVATE uint32_t OI_BITSTREAM_ReadUINT(OI_BITSTREAM* bs, OI_UINT bits) { |
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uint32_t result; |
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OI_BITSTREAM_READUINT(result, bits, bs->ptr.r, bs->value, bs->bitPtr); |
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return result; |
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} |
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PRIVATE uint8_t OI_BITSTREAM_ReadUINT4Aligned(OI_BITSTREAM* bs) { |
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uint32_t result; |
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OI_ASSERT(bs->bitPtr < 16); |
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OI_ASSERT(bs->bitPtr % 4 == 0); |
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if (bs->bitPtr == 8) { |
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result = bs->value << 8; |
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bs->bitPtr = 12; |
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} else { |
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result = bs->value << 12; |
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bs->value = (bs->value << 8) | *bs->ptr.r++; |
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bs->bitPtr = 8; |
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} |
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result >>= 28; |
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OI_ASSERT(result < (1u << 4)); |
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return (uint8_t)result; |
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} |
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PRIVATE uint8_t OI_BITSTREAM_ReadUINT8Aligned(OI_BITSTREAM* bs) { |
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uint32_t result; |
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OI_ASSERT(bs->bitPtr == 8); |
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result = bs->value >> 16; |
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bs->value = (bs->value << 8) | *bs->ptr.r++; |
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return (uint8_t)result; |
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} |
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/** |
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@} |
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*/
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