174 lines
4.8 KiB
C++
174 lines
4.8 KiB
C++
/* ------------------------------------------------------------------
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* Copyright (C) 1998-2009 PacketVideo
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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
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* express or implied.
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* See the License for the specific language governing permissions
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* and limitations under the License.
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* -------------------------------------------------------------------
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*/
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/*
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------------------------------------------------------------------------------
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PacketVideo Corp.
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MP3 Decoder Library
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Filename: pvmp3_normalize.cpp
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Date: 10/02/2007
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------------------------------------------------------------------------------
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REVISION HISTORY
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Description:
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------------------------------------------------------------------------------
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INPUT AND OUTPUT DEFINITIONS
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Input
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Int32 x 32-bit integer non-zero input
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Returns
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Int32 i number of leading zeros on x
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------------------------------------------------------------------------------
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FUNCTION DESCRIPTION
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Returns number of leading zeros on the non-zero input
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------------------------------------------------------------------------------
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REQUIREMENTS
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------------------------------------------------------------------------------
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REFERENCES
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------------------------------------------------------------------------------
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PSEUDO-CODE
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------------------------------------------------------------------------------
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*/
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/*----------------------------------------------------------------------------
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; INCLUDES
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----------------------------------------------------------------------------*/
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#include "pvmp3_audio_type_defs.h"
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#include "pvmp3_normalize.h"
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/*----------------------------------------------------------------------------
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; MACROS
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; Define module specific macros here
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----------------------------------------------------------------------------*/
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/*----------------------------------------------------------------------------
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; DEFINES
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; Include all pre-processor statements here. Include conditional
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; compile variables also.
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----------------------------------------------------------------------------*/
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/*----------------------------------------------------------------------------
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; LOCAL FUNCTION DEFINITIONS
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; Function Prototype declaration
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----------------------------------------------------------------------------*/
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/*----------------------------------------------------------------------------
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; LOCAL STORE/BUFFER/POINTER DEFINITIONS
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; Variable declaration - defined here and used outside this module
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----------------------------------------------------------------------------*/
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/*----------------------------------------------------------------------------
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; EXTERNAL FUNCTION REFERENCES
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; Declare functions defined elsewhere and referenced in this module
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----------------------------------------------------------------------------*/
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/*----------------------------------------------------------------------------
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; EXTERNAL GLOBAL STORE/BUFFER/POINTER REFERENCES
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; Declare variables used in this module but defined elsewhere
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----------------------------------------------------------------------------*/
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/*----------------------------------------------------------------------------
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; FUNCTION CODE
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----------------------------------------------------------------------------*/
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#if (defined(PV_ARM_V5)||defined(PV_ARM_V4))
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#elif (defined(PV_ARM_GCC_V5)||defined(PV_ARM_GCC_V4))
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/* function is inlined in header file */
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#else
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int32 pvmp3_normalize(int32 x)
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{
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/*----------------------------------------------------------------------------
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; Define all local variables
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----------------------------------------------------------------------------*/
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int32 i;
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if (x > 0x0FFFFFFF)
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{
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i = 0; /* most likely case */
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}
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else if (x > 0x00FFFFFF)
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{
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i = 3; /* second most likely case */
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}
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else if (x > 0x0000FFFF)
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{
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i = x > 0x000FFFFF ? 7 : 11;
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}
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else
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{
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if (x > 0x000000FF)
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{
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i = x > 0x00000FFF ? 15 : 19;
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}
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else
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{
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i = x > 0x0000000F ? 23 : 27;
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}
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}
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x <<= i;
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switch (x & 0x78000000)
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{
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case 0x08000000:
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i += 3;
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break;
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case 0x18000000:
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case 0x10000000:
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i += 2;
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break;
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case 0x28000000:
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case 0x20000000:
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case 0x38000000:
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case 0x30000000:
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i++;
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default:
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;
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}
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return i;
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}
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#endif
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