| /* ------------------------------------------------------------------ |
| * Copyright (C) 1998-2009 PacketVideo |
| * |
| * Licensed under the Apache License, Version 2.0 (the "License"); |
| * you may not use this file except in compliance with the License. |
| * You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either |
| * express or implied. |
| * See the License for the specific language governing permissions |
| * and limitations under the License. |
| * ------------------------------------------------------------------- |
| */ |
| #include "mp4dec_lib.h" |
| #include "vlc_decode.h" |
| #include "bitstream.h" |
| #include "zigzag.h" |
| |
| PV_STATUS PV_DecodePredictedIntraDC( |
| int compnum, |
| BitstreamDecVideo *stream, |
| int16 *INTRADC_delta) |
| { |
| |
| /*---------------------------------------------------------------------------- |
| ; Define all local variables |
| ----------------------------------------------------------------------------*/ |
| PV_STATUS status = PV_SUCCESS; |
| uint DC_size; |
| uint code; |
| int first_bit; |
| |
| /*---------------------------------------------------------------------------- |
| ; Function body here |
| ----------------------------------------------------------------------------*/ |
| /* read DC size 2 - 8 bits */ |
| status = PV_VlcDecIntraDCPredSize(stream, compnum, &DC_size); |
| |
| if (status == PV_SUCCESS) |
| { |
| if (DC_size == 0) |
| { |
| *INTRADC_delta = 0; |
| } |
| else |
| { |
| /* read delta DC 0 - 8 bits */ |
| code = (int) BitstreamReadBits16_INLINE(stream, DC_size); |
| |
| first_bit = code >> (DC_size - 1); |
| |
| if (first_bit == 0) |
| { |
| /* negative delta INTRA DC */ |
| *INTRADC_delta = code ^((1 << DC_size) - 1); |
| *INTRADC_delta = -(*INTRADC_delta); |
| } |
| else |
| { /* positive delta INTRA DC */ |
| *INTRADC_delta = code; |
| } |
| if (DC_size > 8) BitstreamRead1Bits_INLINE(stream); |
| } |
| } |
| |
| /*---------------------------------------------------------------------------- |
| ; Return nothing or data or data pointer |
| ----------------------------------------------------------------------------*/ |
| return status; |
| } |
| |