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 31 Pathname: ./gsm-amr/c/src/norm_s.c 32 33 ------------------------------------------------------------------------------ 34 REVISION HISTORY 35 36 Description: Created separate file for the norm_s function. Sync'ed up 37 with the current template and fixed tabs. 38 39 Description: Updated input/output definition and module description to 40 be the same as the equivalent assembly file (norm_s.asm). 41 42 Description: Updated definition of var1 to be the same as that in the 43 assembly file (norm_s.asm). 44 45 Description: Removed conditional code that updates WMOPS counter 46 47 Who: Date: 48 Description: 49 50 ------------------------------------------------------------------------------ 51 INPUT AND OUTPUT DEFINITIONS 52 53 Inputs: 54 var1 = 16 bit signed integer of type Word16, whose value falls 55 in the range: 0x8000 <= var1 <= 0x7fff 56 57 Local Stores/Buffers/Pointers Needed: 58 None 59 60 Global Stores/Buffers/Pointers Needed: 61 None 62 63 Outputs: 64 var_out = number of left shifts need to normalize var1 (Word16) 65 66 Pointers and Buffers Modified: 67 None 68 69 Local Stores Modified: 70 None 71 72 Global Stores Modified: 73 None 74 75 ------------------------------------------------------------------------------ 76 FUNCTION DESCRIPTION 77 78 This function produces the number of left shifts needed to normalize the 16 79 bit variable var1 for positive values on the interval with minimum of 0x4000 80 and maximum of 0x7fff, and for negative values on the interval with minimum 81 of 0x8000 and maximum of 0xc000. Note that when var1 is zero, the resulting 82 output var_out is set to zero. 83 84 ------------------------------------------------------------------------------ 85 REQUIREMENTS 86 87 None 88 89 ------------------------------------------------------------------------------ 90 REFERENCES 91 92 [1] basicop2.c, ETS Version 2.0.0, February 8, 1999 93 94 ------------------------------------------------------------------------------ 95 PSEUDO-CODE 96 97 Word16 norm_s (Word16 var1) 98 { 99 Word16 var_out; 100 101 if (var1 == 0) 102 { 103 var_out = 0; 104 } 105 else 106 { 107 if (var1 == (Word16) 0xffff) 108 { 109 var_out = 15; 110 } 111 else 112 { 113 if (var1 < 0) 114 { 115 var1 = ~var1; 116 } 117 for (var_out = 0; var1 < 0x4000; var_out++) 118 { 119 var1 <<= 1; 120 } 121 } 122 } 123 124 #if (WMOPS) 125 multiCounter[currCounter].norm_s++; 126 #endif 127 return (var_out); 128 } 129 130 ------------------------------------------------------------------------------ 131 RESOURCES USED 132 When the code is written for a specific target processor the 133 the resources used should be documented below. 134 135 STACK USAGE: [stack count for this module] + [variable to represent 136 stack usage for each subroutine called] 137 138 where: [stack usage variable] = stack usage for [subroutine 139 name] (see [filename].ext) 140 141 DATA MEMORY USED: x words 142 143 PROGRAM MEMORY USED: x words 144 145 CLOCK CYCLES: [cycle count equation for this module] + [variable 146 used to represent cycle count for each subroutine 147 called] 148 149 where: [cycle count variable] = cycle count for [subroutine 150 name] (see [filename].ext) 151 152 ------------------------------------------------------------------------------ 153 */ 154 155 156 /*---------------------------------------------------------------------------- 157 ; INCLUDES 158 ----------------------------------------------------------------------------*/ 159 #include "basic_op.h" 160 161 /*---------------------------------------------------------------------------- 162 ; MACROS 163 ; Define module specific macros here 164 ----------------------------------------------------------------------------*/ 165 166 /*---------------------------------------------------------------------------- 167 ; DEFINES 168 ; Include all pre-processor statements here. Include conditional 169 ; compile variables also. 170 ----------------------------------------------------------------------------*/ 171 172 /*---------------------------------------------------------------------------- 173 ; LOCAL FUNCTION DEFINITIONS 174 ; Function Prototype declaration 175 ----------------------------------------------------------------------------*/ 176 177 /*---------------------------------------------------------------------------- 178 ; LOCAL STORE/BUFFER/POINTER DEFINITIONS 179 ; Variable declaration - defined here and used outside this module 180 ----------------------------------------------------------------------------*/ 181 182 /*---------------------------------------------------------------------------- 183 ; EXTERNAL FUNCTION REFERENCES 184 ; Declare functions defined elsewhere and referenced in this module 185 ----------------------------------------------------------------------------*/ 186 187 /*---------------------------------------------------------------------------- 188 ; EXTERNAL GLOBAL STORE/BUFFER/POINTER REFERENCES 189 ; Declare variables used in this module but defined elsewhere 190 ----------------------------------------------------------------------------*/ 191 192 /*---------------------------------------------------------------------------- 193 ; FUNCTION CODE 194 ----------------------------------------------------------------------------*/ 195 #if !( defined(PV_ARM_V5) || defined(PV_ARM_GCC_V5) ) 196 197 Word16 norm_s(Word16 var1) 198 { 199 /*---------------------------------------------------------------------------- 200 ; Define all local variables 201 ----------------------------------------------------------------------------*/ 202 203 Word16 var_out = 0; 204 205 /*---------------------------------------------------------------------------- 206 ; Function body here 207 ----------------------------------------------------------------------------*/ 208 209 if (var1) 210 { 211 Word16 y = var1 - (var1 < 0); 212 var1 = y ^(y >> 15); 213 214 while (!(0x4000 & var1)) 215 { 216 var_out++; 217 if ((0x2000 & var1)) 218 { 219 break; 220 } 221 var_out++; 222 if ((0x1000 & var1)) 223 { 224 break; 225 } 226 var_out++; 227 if ((0x0800 & var1)) 228 { 229 break; 230 } 231 var_out++; 232 var1 <<= 4; 233 } 234 } 235 236 /*---------------------------------------------------------------------------- 237 ; Return nothing or data or data pointer 238 ----------------------------------------------------------------------------*/ 239 return (var_out); 240 } 241 242 #endif 243
