1 /* ------------------------------------------------------------------ 2 * Copyright (C) 1998-2009 PacketVideo 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either 13 * express or implied. 14 * See the License for the specific language governing permissions 15 * and limitations under the License. 16 * ------------------------------------------------------------------- 17 */ 18 /**************************************************************************************** 19 Portions of this file are derived from the following 3GPP standard: 20 21 3GPP TS 26.073 22 ANSI-C code for the Adaptive Multi-Rate (AMR) speech codec 23 Available from http://www.3gpp.org 24 25 (C) 2004, 3GPP Organizational Partners (ARIB, ATIS, CCSA, ETSI, TTA, TTC) 26 Permission to distribute, modify and use this file under the standard license 27 terms listed above has been obtained from the copyright holder. 28 ****************************************************************************************/ 29 /* 30 Pathname: ./audio/gsm-amr/c/src/lsfwt.c 31 Functions: Lsf_wt 32 33 ------------------------------------------------------------------------------ 34 REVISION HISTORY 35 36 Description: Updated to accept new parameter, Flag *pOverflow. Placed 37 file in the proper PV Software template. 38 39 Description: 40 1. Eliminated unused include files. 41 2. Replaced array addressing by pointers 42 3. Eliminated math operations that unnecessary checked for 43 saturation, by evaluating the operands 44 4. Unrolled loops to speed up processing, use decrement loops 45 46 Description: Replaced "int" and/or "char" with OSCL defined types. 47 48 Who: Date: 49 Description: 50 51 ------------------------------------------------------------------------------ 52 INPUT AND OUTPUT DEFINITIONS 53 54 Inputs: 55 lsf -- Pointer to Word16 -- LSF vector 56 57 Outputs: 58 wf -- Pointer to Word16 -- square of weighting factors 59 pOverflow -- Pointer to type Flag -- Flag set when overflow occurs 60 61 Returns: 62 None 63 64 Global Variables Used: 65 None 66 67 Local Variables Needed: 68 None 69 70 ------------------------------------------------------------------------------ 71 FUNCTION DESCRIPTION 72 73 Compute LSF weighting factors 74 75 d[i] = lsf[i+1] - lsf[i-1] 76 77 The weighting factors are approximated by two line segment 78 79 First segment passes by the following 2 points: 80 81 d[i] = 0Hz wf[i] = 3.347 82 d[i] = 450Hz wf[i] = 1.8 83 84 Second segment passes by the following 2 points: 85 86 d[i] = 450Hz wf[i] = 1.8 87 d[i] = 1500Hz wf[i] = 1.0 88 89 if( d[i] < 450Hz ) 90 wf[i] = 3.347 - ( (3.347-1.8) / (450-0)) * d[i] 91 else 92 wf[i] = 1.8 - ( (1.8-1.0) / (1500-450)) * (d[i] - 450) 93 94 95 if( d[i] < 1843) 96 wf[i] = 3427 - (28160*d[i])>>15 97 else 98 wf[i] = 1843 - (6242*(d[i]-1843))>>15 99 100 ------------------------------------------------------------------------------ 101 REQUIREMENTS 102 103 104 105 ------------------------------------------------------------------------------ 106 REFERENCES 107 108 lsfwt.c, UMTS GSM AMR speech codec, R99 - Version 3.2.0, March 2, 2001 109 110 ------------------------------------------------------------------------------ 111 PSEUDO-CODE 112 113 114 115 ------------------------------------------------------------------------------ 116 RESOURCES USED 117 When the code is written for a specific target processor the 118 the resources used should be documented below. 119 120 STACK USAGE: [stack count for this module] + [variable to represent 121 stack usage for each subroutine called] 122 123 where: [stack usage variable] = stack usage for [subroutine 124 name] (see [filename].ext) 125 126 DATA MEMORY USED: x words 127 128 PROGRAM MEMORY USED: x words 129 130 CLOCK CYCLES: [cycle count equation for this module] + [variable 131 used to represent cycle count for each subroutine 132 called] 133 134 where: [cycle count variable] = cycle count for [subroutine 135 name] (see [filename].ext) 136 137 ------------------------------------------------------------------------------ 138 */ 139 140 141 /*---------------------------------------------------------------------------- 142 ; INCLUDES 143 ----------------------------------------------------------------------------*/ 144 #include "lsfwt.h" 145 #include "cnst.h" 146 147 /*---------------------------------------------------------------------------- 148 ; MACROS 149 ; Define module specific macros here 150 ----------------------------------------------------------------------------*/ 151 152 153 /*---------------------------------------------------------------------------- 154 ; DEFINES 155 ; Include all pre-processor statements here. Include conditional 156 ; compile variables also. 157 ----------------------------------------------------------------------------*/ 158 159 160 /*---------------------------------------------------------------------------- 161 ; LOCAL FUNCTION DEFINITIONS 162 ; Function Prototype declaration 163 ----------------------------------------------------------------------------*/ 164 165 166 /*---------------------------------------------------------------------------- 167 ; LOCAL STORE/BUFFER/POINTER DEFINITIONS 168 ; Variable declaration - defined here and used outside this module 169 ----------------------------------------------------------------------------*/ 170 171 /*---------------------------------------------------------------------------- 172 ; EXTERNAL FUNCTION REFERENCES 173 ; Declare functions defined elsewhere and referenced in this module 174 ----------------------------------------------------------------------------*/ 175 176 /*---------------------------------------------------------------------------- 177 ; EXTERNAL GLOBAL STORE/BUFFER/POINTER REFERENCES 178 ; Declare variables used in this module but defined elsewhere 179 ----------------------------------------------------------------------------*/ 180 181 182 /*---------------------------------------------------------------------------- 183 ; FUNCTION CODE 184 ----------------------------------------------------------------------------*/ 185 186 void Lsf_wt( 187 Word16 *lsf, /* input : LSF vector */ 188 Word16 *wf, /* output: square of weighting factors */ 189 Flag *pOverflow 190 ) 191 { 192 Word16 temp; 193 Word16 wgt_fct; 194 Word16 i; 195 Word16 *p_wf = wf; 196 Word16 *p_lsf = &lsf[0]; 197 Word16 *p_lsf_2 = &lsf[1]; 198 199 OSCL_UNUSED_ARG(pOverflow); 200 201 /* wf[0] = lsf[1] - 0 */ 202 *(p_wf++) = *(p_lsf_2++); 203 204 for (i = 4; i != 0 ; i--) 205 { 206 *(p_wf++) = *(p_lsf_2++) - *(p_lsf++); 207 *(p_wf++) = *(p_lsf_2++) - *(p_lsf++); 208 } 209 /* 210 * wf[9] = 4000 - lsf[8] 211 */ 212 *(p_wf) = 16384 - *(p_lsf); 213 214 p_wf = wf; 215 216 for (i = 10; i != 0; i--) 217 { 218 /* 219 * (wf[i] - 450); 220 * 1843 == 450 Hz (Q15 considering 7FFF = 8000 Hz) 221 */ 222 wgt_fct = *p_wf; 223 temp = wgt_fct - 1843; 224 225 if (temp > 0) 226 { 227 temp = (Word16)(((Word32)temp * 6242) >> 15); 228 wgt_fct = 1843 - temp; 229 } 230 else 231 { 232 temp = (Word16)(((Word32)wgt_fct * 28160) >> 15); 233 wgt_fct = 3427 - temp; 234 } 235 236 *(p_wf++) = wgt_fct << 3; 237 238 } /* for (i = 10; i != 0; i--) */ 239 240 return; 241 242 } /* Lsf_wt() */ 243
