| /* ------------------------------------------------------------------ |
| * 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() */ |