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Diffstat (limited to 'media/libstagefright/codecs/amrnb/common/src/log2.cpp')
| -rw-r--r-- | media/libstagefright/codecs/amrnb/common/src/log2.cpp | 179 |
1 files changed, 179 insertions, 0 deletions
diff --git a/media/libstagefright/codecs/amrnb/common/src/log2.cpp b/media/libstagefright/codecs/amrnb/common/src/log2.cpp new file mode 100644 index 0000000..0ada423 --- /dev/null +++ b/media/libstagefright/codecs/amrnb/common/src/log2.cpp @@ -0,0 +1,179 @@ +/* ------------------------------------------------------------------ + * 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. + * ------------------------------------------------------------------- + */ +/**************************************************************************************** +Portions of this file are derived from the following 3GPP standard: + + 3GPP TS 26.073 + ANSI-C code for the Adaptive Multi-Rate (AMR) speech codec + Available from http://www.3gpp.org + +(C) 2004, 3GPP Organizational Partners (ARIB, ATIS, CCSA, ETSI, TTA, TTC) +Permission to distribute, modify and use this file under the standard license +terms listed above has been obtained from the copyright holder. +****************************************************************************************/ +/* + Filename: /audio/gsm_amr/c/src/log2.c + +------------------------------------------------------------------------------ + REVISION HISTORY + + Description: Updated template used to PV coding template. Moved Log2_norm + function to its own file. + + Description: Changed l_shl.c to l_shl.h in Include section. + + Description: Updated template. Changed function interface to pass in a + pointer to overflow flag into the function instead of using a + global flag. Changed input pointer names for clarity. + + Description: + 1. Eliminated l_shl function knowing that after normalization + the left shift factor will not saturate. + 2. Eliminated unused include files typedef.h and l_shl.h. + + + Who: Date: + Description: + +------------------------------------------------------------------------------ +*/ + +/*---------------------------------------------------------------------------- +; INCLUDES +----------------------------------------------------------------------------*/ +#include "log2.h" +#include "basic_op.h" +#include "log2_norm.h" + +/*---------------------------------------------------------------------------- +; MACROS +; [Define module specific macros here] +----------------------------------------------------------------------------*/ + +/*---------------------------------------------------------------------------- +; DEFINES +; [Include all pre-processor statements here. Include conditional +; compile variables also.] +----------------------------------------------------------------------------*/ + +/*---------------------------------------------------------------------------- +; LOCAL FUNCTION DEFINITIONS +; [List function prototypes here] +----------------------------------------------------------------------------*/ + +/*---------------------------------------------------------------------------- +; LOCAL VARIABLE DEFINITIONS +; [Variable declaration - defined here and used outside this module] +----------------------------------------------------------------------------*/ + + +/* +------------------------------------------------------------------------------ + FUNCTION NAME: log2() +------------------------------------------------------------------------------ + INPUT AND OUTPUT DEFINITIONS + + Inputs: + L_x = input value of type Word32 + pExponent = pointer to the integer part of Log2 of type Word16 whose + valid range is: 0 <= value <= 30 + pFraction = pointer to the fractional part of Log2 of type Word16 + whose valid range is: 0 <= value < 1 + pOverflow = pointer to overflow flag + + + Outputs: + pExponent -> integer part of the newly calculated Log2 + pFraction -> fractional part of the newly calculated Log2 + pOverflow -> 1 if the log2() operation resulted in saturation + + Returns: + None + + Global Variables Used: + None + + Local Variables Needed: + None + +------------------------------------------------------------------------------ + FUNCTION DESCRIPTION + + This function computes logarithm (base2) of the input L_x, where L_x is + positive. If L_x is negative or zero, the result is 0. + + This function first normalizes the input L_x and calls the function Log2_norm + to calculate the logarithm. + +------------------------------------------------------------------------------ + REQUIREMENTS + + None + +------------------------------------------------------------------------------ + REFERENCES + + [1] log2.c, UMTS GSM AMR speech codec, R99 - Version 3.2.0, March 2, 2001 + +------------------------------------------------------------------------------ + PSEUDO-CODE + + +------------------------------------------------------------------------------ + RESOURCES USED [optional] + + When the code is written for a specific target processor the + the resources used should be documented below. + + HEAP MEMORY USED: x bytes + + STACK MEMORY USED: x bytes + + CLOCK CYCLES: (cycle count equation for this function) + (variable + used to represent cycle count for each subroutine + called) + where: (cycle count variable) = cycle count for [subroutine + name] + +------------------------------------------------------------------------------ + CAUTION [optional] + [State any special notes, constraints or cautions for users of this function] + +------------------------------------------------------------------------------ +*/ + +/*---------------------------------------------------------------------------- +; FUNCTION CODE +----------------------------------------------------------------------------*/ +void Log2( + Word32 L_x, /* (i) : input value */ + Word16 *pExponent, /* (o) : Integer part of Log2. (range: 0<=val<=30)*/ + Word16 *pFraction, /* (o) : Fractional part of Log2. (range: 0<=val<1) */ + Flag *pOverflow /* (i/o) : overflow flag */ +) +{ + Word16 exp; + Word32 result; + OSCL_UNUSED_ARG(pOverflow); + + exp = norm_l(L_x); + result = L_x << exp; + Log2_norm(result, exp, pExponent, pFraction); + + return; +} |