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 Filename: /audio/gsm_amr/c/src/add.c 32 33 ------------------------------------------------------------------------------ 34 REVISION HISTORY 35 36 Description: Created separate file for add function. Sync'ed up with the 37 current template and fixed tabs. 38 39 Description: Changed all occurrences of L_sum with sum. 40 41 Description: Changed function protype to pass in pointer to Overflow flag 42 as a parameter. 43 44 Description: Removed code that updates MOPS counter 45 46 Who: Date: 47 Description: 48 49 ------------------------------------------------------------------------------ 50 MODULE DESCRIPTION 51 52 Summation function with overflow control 53 54 ------------------------------------------------------------------------------ 55 */ 56 57 58 /*---------------------------------------------------------------------------- 59 ; INCLUDES 60 ----------------------------------------------------------------------------*/ 61 #include "basic_op.h" 62 63 /*---------------------------------------------------------------------------- 64 ; MACROS 65 ; [Define module specific macros here] 66 ----------------------------------------------------------------------------*/ 67 68 /*---------------------------------------------------------------------------- 69 ; DEFINES 70 ; [Include all pre-processor statements here. Include conditional 71 ; compile variables also.] 72 ----------------------------------------------------------------------------*/ 73 74 /*---------------------------------------------------------------------------- 75 ; LOCAL FUNCTION DEFINITIONS 76 ; [List function prototypes here] 77 ----------------------------------------------------------------------------*/ 78 79 /*---------------------------------------------------------------------------- 80 ; LOCAL VARIABLE DEFINITIONS 81 ; [Variable declaration - defined here and used outside this module] 82 ----------------------------------------------------------------------------*/ 83 84 85 /* 86 ------------------------------------------------------------------------------ 87 FUNCTION NAME: add 88 ------------------------------------------------------------------------------ 89 INPUT AND OUTPUT DEFINITIONS 90 91 Inputs: 92 var1 = 16 bit short signed integer (Word16) whose value falls in 93 the range : 0xffff 8000 <= var1 <= 0x0000 7fff. 94 95 var2 = 16 bit short signed integer (Word16) whose value falls in 96 the range : 0xffff 8000 <= var2 <= 0x0000 7fff. 97 98 pOverflow = pointer to overflow (Flag) 99 100 Outputs: 101 pOverflow -> 1 if the add operation resulted in overflow 102 103 Returns: 104 sum = 16-bit limited sum of var1 and var2 (Word16) 105 106 Global Variables Used: 107 None 108 109 Local Variables Needed: 110 None 111 112 ------------------------------------------------------------------------------ 113 FUNCTION DESCRIPTION 114 115 This function performs the addition (var1+var2) with overflow control and 116 saturation; the 16 bit result is set at +32767 when overflow occurs or at 117 -32768 when underflow occurs. 118 119 ------------------------------------------------------------------------------ 120 REQUIREMENTS 121 122 None 123 124 ------------------------------------------------------------------------------ 125 REFERENCES 126 127 [1] add.c, UMTS GSM AMR speech codec, R99 - Version 3.2.0, March 2, 2001 128 129 ------------------------------------------------------------------------------ 130 PSEUDO-CODE 131 132 Word16 add (Word16 var1, Word16 var2) 133 { 134 Word16 var_out; 135 Word32 sum; 136 137 sum = (Word32) var1 + var2; 138 139 * The reference ETSI code uses a global flag for Overflow inside the function 140 * saturate(). In the actual implementation a pointer to Overflow flag is passed in 141 * as a parameter to the function 142 143 var_out = saturate (sum); 144 #if (WMOPS) 145 multiCounter[currCounter].add++; 146 #endif 147 return (var_out); 148 } 149 150 ------------------------------------------------------------------------------ 151 RESOURCES USED [optional] 152 153 When the code is written for a specific target processor the 154 the resources used should be documented below. 155 156 HEAP MEMORY USED: x bytes 157 158 STACK MEMORY USED: x bytes 159 160 CLOCK CYCLES: (cycle count equation for this function) + (variable 161 used to represent cycle count for each subroutine 162 called) 163 where: (cycle count variable) = cycle count for [subroutine 164 name] 165 166 ------------------------------------------------------------------------------ 167 CAUTION [optional] 168 [State any special notes, constraints or cautions for users of this function] 169 170 ------------------------------------------------------------------------------ 171 */ 172 173 /*---------------------------------------------------------------------------- 174 ; FUNCTION CODE 175 ----------------------------------------------------------------------------*/ 176 Word16 add(Word16 var1, Word16 var2, Flag *pOverflow) 177 { 178 /*---------------------------------------------------------------------------- 179 ; Define all local variables 180 ----------------------------------------------------------------------------*/ 181 Word32 sum; 182 sum = (Word32) var1 + var2; 183 184 /* Saturate result (if necessary). */ 185 /* Replaced function call with in-line code */ 186 /* to conserve MIPS, i.e., var_out = saturate (sum) */ 187 188 if (sum > 0X00007fffL) 189 { 190 *pOverflow = 1; 191 sum = MAX_16; 192 } 193 else if (sum < (Word32) 0xffff8000L) 194 { 195 *pOverflow = 1; 196 sum = MIN_16; 197 } 198 199 /* Return the sum as a 16 bit value by type casting Word32 to Word16 */ 200 201 return ((Word16) sum); 202 } 203 204
