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