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Diffstat (limited to 'media/libstagefright/codecs/amrnb/common/src/lsfwt.cpp')
| -rw-r--r-- | media/libstagefright/codecs/amrnb/common/src/lsfwt.cpp | 242 |
1 files changed, 242 insertions, 0 deletions
diff --git a/media/libstagefright/codecs/amrnb/common/src/lsfwt.cpp b/media/libstagefright/codecs/amrnb/common/src/lsfwt.cpp new file mode 100644 index 0000000..6b511f7 --- /dev/null +++ b/media/libstagefright/codecs/amrnb/common/src/lsfwt.cpp @@ -0,0 +1,242 @@ +/* ------------------------------------------------------------------ + * 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. +****************************************************************************************/ +/* + Pathname: ./audio/gsm-amr/c/src/lsfwt.c + Functions: Lsf_wt + +------------------------------------------------------------------------------ + REVISION HISTORY + + Description: Updated to accept new parameter, Flag *pOverflow. Placed + file in the proper PV Software template. + + Description: + 1. Eliminated unused include files. + 2. Replaced array addressing by pointers + 3. Eliminated math operations that unnecessary checked for + saturation, by evaluating the operands + 4. Unrolled loops to speed up processing, use decrement loops + + Description: Replaced "int" and/or "char" with OSCL defined types. + + Who: Date: + Description: + + ------------------------------------------------------------------------------ + INPUT AND OUTPUT DEFINITIONS + + Inputs: + lsf -- Pointer to Word16 -- LSF vector + + Outputs: + wf -- Pointer to Word16 -- square of weighting factors + pOverflow -- Pointer to type Flag -- Flag set when overflow occurs + + Returns: + None + + Global Variables Used: + None + + Local Variables Needed: + None + +------------------------------------------------------------------------------ + FUNCTION DESCRIPTION + +Compute LSF weighting factors + + d[i] = lsf[i+1] - lsf[i-1] + + The weighting factors are approximated by two line segment + + First segment passes by the following 2 points: + + d[i] = 0Hz wf[i] = 3.347 + d[i] = 450Hz wf[i] = 1.8 + + Second segment passes by the following 2 points: + + d[i] = 450Hz wf[i] = 1.8 + d[i] = 1500Hz wf[i] = 1.0 + + if( d[i] < 450Hz ) + wf[i] = 3.347 - ( (3.347-1.8) / (450-0)) * d[i] + else + wf[i] = 1.8 - ( (1.8-1.0) / (1500-450)) * (d[i] - 450) + + + if( d[i] < 1843) + wf[i] = 3427 - (28160*d[i])>>15 + else + wf[i] = 1843 - (6242*(d[i]-1843))>>15 + +------------------------------------------------------------------------------ + REQUIREMENTS + + + +------------------------------------------------------------------------------ + REFERENCES + + lsfwt.c, UMTS GSM AMR speech codec, R99 - Version 3.2.0, March 2, 2001 + +------------------------------------------------------------------------------ + PSEUDO-CODE + + + +------------------------------------------------------------------------------ + RESOURCES USED + When the code is written for a specific target processor the + the resources used should be documented below. + + STACK USAGE: [stack count for this module] + [variable to represent + stack usage for each subroutine called] + + where: [stack usage variable] = stack usage for [subroutine + name] (see [filename].ext) + + DATA MEMORY USED: x words + + PROGRAM MEMORY USED: x words + + CLOCK CYCLES: [cycle count equation for this module] + [variable + used to represent cycle count for each subroutine + called] + + where: [cycle count variable] = cycle count for [subroutine + name] (see [filename].ext) + +------------------------------------------------------------------------------ +*/ + + +/*---------------------------------------------------------------------------- +; INCLUDES +----------------------------------------------------------------------------*/ +#include "lsfwt.h" +#include "cnst.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 +----------------------------------------------------------------------------*/ + +void Lsf_wt( + Word16 *lsf, /* input : LSF vector */ + Word16 *wf, /* output: square of weighting factors */ + Flag *pOverflow +) +{ + Word16 temp; + Word16 wgt_fct; + Word16 i; + Word16 *p_wf = wf; + Word16 *p_lsf = &lsf[0]; + Word16 *p_lsf_2 = &lsf[1]; + + OSCL_UNUSED_ARG(pOverflow); + + /* wf[0] = lsf[1] - 0 */ + *(p_wf++) = *(p_lsf_2++); + + for (i = 4; i != 0 ; i--) + { + *(p_wf++) = *(p_lsf_2++) - *(p_lsf++); + *(p_wf++) = *(p_lsf_2++) - *(p_lsf++); + } + /* + * wf[9] = 4000 - lsf[8] + */ + *(p_wf) = 16384 - *(p_lsf); + + p_wf = wf; + + for (i = 10; i != 0; i--) + { + /* + * (wf[i] - 450); + * 1843 == 450 Hz (Q15 considering 7FFF = 8000 Hz) + */ + wgt_fct = *p_wf; + temp = wgt_fct - 1843; + + if (temp > 0) + { + temp = (Word16)(((Word32)temp * 6242) >> 15); + wgt_fct = 1843 - temp; + } + else + { + temp = (Word16)(((Word32)wgt_fct * 28160) >> 15); + wgt_fct = 3427 - temp; + } + + *(p_wf++) = wgt_fct << 3; + + } /* for (i = 10; i != 0; i--) */ + + return; + +} /* Lsf_wt() */ |