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/round.c 32 33 ------------------------------------------------------------------------------ 34 REVISION HISTORY 35 36 Description: Created separate file for the round function. Sync'ed up 37 with the current template and fixed tabs. 38 39 Description: Made changes based on review meeting: 40 1. Removed long in Inputs Definitions. 41 2. Changed L_var1 to var_out and description in 42 Output Definitions. 43 44 Description: Added a parameter to the function interface, pOverflow which is 45 a pointer to the overflow flag. This flag is required by the 46 L_add() function invoked by round(). 47 Removed code that updates the MOPS counter. 48 Created a new return variable result. 49 50 Description: Removed embedded tabs. Included comment in the Pseudo code 51 Section about using pointer to overflow flag in the actual 52 implementation instead of using a global flag. 53 54 Description: Changed function name to pv_round to avoid conflict with 55 round function in C standard library. 56 57 Who: Date: 58 Description: 59 60 ------------------------------------------------------------------------------ 61 MODULE DESCRIPTION 62 63 Rounding function with saturation. 64 65 ------------------------------------------------------------------------------ 66 */ 67 68 /*---------------------------------------------------------------------------- 69 ; INCLUDES 70 ----------------------------------------------------------------------------*/ 71 #include "basic_op.h" 72 73 /*---------------------------------------------------------------------------- 74 ; MACROS 75 ; [Define module specific macros here] 76 ----------------------------------------------------------------------------*/ 77 78 /*---------------------------------------------------------------------------- 79 ; DEFINES 80 ; [Include all pre-processor statements here. Include conditional 81 ; compile variables also.] 82 ----------------------------------------------------------------------------*/ 83 84 /*---------------------------------------------------------------------------- 85 ; LOCAL FUNCTION DEFINITIONS 86 ; [List function prototypes here] 87 ----------------------------------------------------------------------------*/ 88 89 /*---------------------------------------------------------------------------- 90 ; LOCAL VARIABLE DEFINITIONS 91 ; [Variable declaration - defined here and used outside this module] 92 ----------------------------------------------------------------------------*/ 93 94 /* 95 ------------------------------------------------------------------------------ 96 FUNCTION NAME: pv_round 97 ------------------------------------------------------------------------------ 98 INPUT AND OUTPUT DEFINITIONS 99 100 Inputs: 101 L_var1 = 32 bit signed integer (Word32) whose value falls 102 in the range : 0x8000 0000 <= L_var1 <= 0x7fff ffff. 103 104 pOverflow = pointer to overflow (Flag) 105 106 Outputs: 107 None 108 109 Returns: 110 result = MS 16 bits of rounded input L_var1. 111 112 Global Variables Used: 113 None 114 115 Local Variables Needed: 116 None 117 118 ------------------------------------------------------------------------------ 119 FUNCTION DESCRIPTION 120 121 This function rounds the lower 16 bits of the 32 bit input number into the 122 MS 16 bits with saturation. Shift the resulting bits right by 16 and return 123 the 16 bit number: 124 pv_round(L_var1) = extract_h(L_add(L_var1,32768)) 125 126 ------------------------------------------------------------------------------ 127 REQUIREMENTS 128 129 None 130 131 ------------------------------------------------------------------------------ 132 REFERENCES 133 134 [1] round() function in basic_op2.c, UMTS GSM AMR speech codec, R99 - 135 Version 3.2.0, March 2, 2001 136 137 ------------------------------------------------------------------------------ 138 PSEUDO-CODE 139 140 Word16 pv_round (Word32 L_var1) 141 { 142 Word16 var_out; 143 Word32 L_rounded; 144 145 * The reference ETSI code uses a global flag for Overflow in the L_add() function. 146 * In the actual implementation a pointer to Overflow flag is passed in as a 147 * parameter to the function. 148 149 L_rounded = L_add (L_var1, (Word32) 0x00008000L); 150 #if (WMOPS) 151 multiCounter[currCounter].L_add--; 152 #endif 153 var_out = extract_h (L_rounded); 154 #if (WMOPS) 155 multiCounter[currCounter].extract_h--; 156 multiCounter[currCounter].round++; 157 #endif 158 return (var_out); 159 } 160 161 ------------------------------------------------------------------------------ 162 RESOURCES USED [optional] 163 164 When the code is written for a specific target processor the 165 the resources used should be documented below. 166 167 HEAP MEMORY USED: x bytes 168 169 STACK MEMORY USED: x bytes 170 171 CLOCK CYCLES: (cycle count equation for this function) + (variable 172 used to represent cycle count for each subroutine 173 called) 174 where: (cycle count variable) = cycle count for [subroutine 175 name] 176 177 ------------------------------------------------------------------------------ 178 CAUTION [optional] 179 [State any special notes, constraints or cautions for users of this function] 180 181 ------------------------------------------------------------------------------ 182 */ 183 184 /*---------------------------------------------------------------------------- 185 ; FUNCTION CODE 186 ----------------------------------------------------------------------------*/ 187 Word16 pv_round(register Word32 L_var1, Flag *pOverflow) 188 { 189 Word16 result; 190 191 L_var1 = L_add(L_var1, (Word32) 0x00008000L, pOverflow); 192 result = (Word16)(L_var1 >> 16); 193 194 return (result); 195 } 196
