1/******************************************************************************
2 *
3 *  Copyright (C) 2014 The Android Open Source Project
4 *  Copyright 2003 - 2004 Open Interface North America, Inc. All rights reserved.
5 *
6 *  Licensed under the Apache License, Version 2.0 (the "License");
7 *  you may not use this file except in compliance with the License.
8 *  You may obtain a copy of the License at:
9 *
10 *  http://www.apache.org/licenses/LICENSE-2.0
11 *
12 *  Unless required by applicable law or agreed to in writing, software
13 *  distributed under the License is distributed on an "AS IS" BASIS,
14 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
15 *  See the License for the specific language governing permissions and
16 *  limitations under the License.
17 *
18 ******************************************************************************/
19
20/**********************************************************************************
21  $Revision: #1 $
22***********************************************************************************/
23
24/**
25@file
26Functions for manipulating input bitstreams.
27
28@ingroup codec_internal
29*/
30
31/**
32@addtogroup codec_internal
33@{
34*/
35
36#include "oi_stddefs.h"
37#include "oi_bitstream.h"
38#include "oi_assert.h"
39
40PRIVATE void OI_BITSTREAM_ReadInit(OI_BITSTREAM *bs,
41                                   const OI_BYTE *buffer)
42{
43    bs->value = ((OI_INT32)buffer[0] << 16) | ((OI_INT32)buffer[1] << 8) | (buffer[2]);
44    bs->ptr.r = buffer + 3;
45    bs->bitPtr = 8;
46}
47
48PRIVATE OI_UINT32 OI_BITSTREAM_ReadUINT(OI_BITSTREAM *bs, OI_UINT bits)
49{
50    OI_UINT32 result;
51
52    OI_BITSTREAM_READUINT(result, bits, bs->ptr.r, bs->value, bs->bitPtr);
53
54    return result;
55}
56
57PRIVATE OI_UINT8 OI_BITSTREAM_ReadUINT4Aligned(OI_BITSTREAM *bs)
58{
59    OI_UINT32 result;
60
61    OI_ASSERT(bs->bitPtr < 16);
62    OI_ASSERT(bs->bitPtr % 4 == 0);
63
64    if (bs->bitPtr == 8) {
65        result = bs->value << 8;
66        bs->bitPtr = 12;
67    } else {
68        result = bs->value << 12;
69        bs->value = (bs->value << 8) | *bs->ptr.r++;
70        bs->bitPtr = 8;
71    }
72    result >>= 28;
73    OI_ASSERT(result < (1u << 4));
74    return (OI_UINT8)result;
75}
76
77PRIVATE OI_UINT8 OI_BITSTREAM_ReadUINT8Aligned(OI_BITSTREAM *bs)
78{
79    OI_UINT32 result;
80    OI_ASSERT(bs->bitPtr == 8);
81
82    result = bs->value >> 16;
83    bs->value = (bs->value << 8) | *bs->ptr.r++;
84
85    return (OI_UINT8)result;
86}
87
88/**
89@}
90*/
91
92
93