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 20 Filename: pv_sqrt.c 21 22 ------------------------------------------------------------------------------ 23 REVISION HISTORY 24 25 26 Who: Date: MM/DD/YYYY 27 Description: 28 29 ------------------------------------------------------------------------------ 30 INPUT AND OUTPUT DEFINITIONS 31 32 Int32 x 32-bit integer 33 34 Int32 y 32-bit integer 35 36 37 ------------------------------------------------------------------------------ 38 FUNCTION DESCRIPTION 39 40 Implement root squared of a number 41 42 ------------------------------------------------------------------------------ 43 REQUIREMENTS 44 45 46 ------------------------------------------------------------------------------ 47 REFERENCES 48 49 ------------------------------------------------------------------------------ 50 PSEUDO-CODE 51 52 ------------------------------------------------------------------------------ 53 */ 54 55 56 /*---------------------------------------------------------------------------- 57 ; INCLUDES 58 ----------------------------------------------------------------------------*/ 59 60 #ifdef AAC_PLUS 61 62 63 #include "pv_audio_type_defs.h" 64 65 #include "fxp_mul32.h" 66 #include "pv_sqrt.h" 67 68 69 /*---------------------------------------------------------------------------- 70 ; MACROS 71 ; Define module specific macros here 72 ----------------------------------------------------------------------------*/ 73 74 75 /*---------------------------------------------------------------------------- 76 ; DEFINES 77 ; Include all pre-processor statements here. Include conditional 78 ; compile variables also. 79 ----------------------------------------------------------------------------*/ 80 81 /*---------------------------------------------------------------------------- 82 ; LOCAL FUNCTION DEFINITIONS 83 ; Function Prototype declaration 84 ----------------------------------------------------------------------------*/ 85 #define R_SHIFT 28 86 #define Q_fmt(x) (Int32)(x*((Int32)1<<R_SHIFT) + (x>=0?0.5F:-0.5F)) 87 88 89 const Int32 sqrt_table[9] = 90 { 91 Q_fmt(-0.13829740941110F), Q_fmt(0.95383399963991F), 92 Q_fmt(-2.92784603873353F), Q_fmt(5.27429191920042F), 93 Q_fmt(-6.20272445821478F), Q_fmt(5.04717433019620F), 94 Q_fmt(-3.03362807640415F), Q_fmt(1.86178814410910F), 95 Q_fmt(0.16540758699193F) 96 }; 97 98 /*---------------------------------------------------------------------------- 99 ; LOCAL STORE/BUFFER/POINTER DEFINITIONS 100 ; Variable declaration - defined here and used outside this module 101 ----------------------------------------------------------------------------*/ 102 103 /*---------------------------------------------------------------------------- 104 ; EXTERNAL FUNCTION REFERENCES 105 ; Declare functions defined elsewhere and referenced in this module 106 ----------------------------------------------------------------------------*/ 107 108 /*---------------------------------------------------------------------------- 109 ; EXTERNAL GLOBAL STORE/BUFFER/POINTER REFERENCES 110 ; Declare variables used in this module but defined elsewhere 111 ----------------------------------------------------------------------------*/ 112 113 /*---------------------------------------------------------------------------- 114 ; FUNCTION CODE 115 ----------------------------------------------------------------------------*/ 116 117 118 void pv_sqrt(Int32 man, Int32 exp, Root_sq *result, Int32 *sqrt_cache) 119 { 120 121 Int32 y; 122 Int32 xx; 123 Int32 nn; 124 Int32 i; 125 const Int32 *pt_table = sqrt_table; 126 127 128 if (sqrt_cache[0] == man && sqrt_cache[1] == exp) 129 { 130 result->root = sqrt_cache[2]; 131 result->shift_factor = (Int16)sqrt_cache[3]; 132 } 133 else 134 { 135 136 sqrt_cache[0] = man; 137 sqrt_cache[1] = exp; 138 139 140 if (man > 0) 141 { 142 xx = man; 143 if (man >= Q_fmt(1.0f)) 144 { 145 nn = exp + 1; 146 while ((xx >>= 1) > Q_fmt(1.0f)) 147 { 148 nn++; 149 } 150 } 151 else if (man < Q_fmt(0.5f)) 152 { 153 nn = exp - 1; 154 while ((xx <<= 1) < Q_fmt(0.5f)) 155 { 156 nn--; 157 } 158 } 159 else 160 { 161 nn = exp; 162 } 163 164 165 y = fxp_mul32_Q28(*(pt_table++), xx); 166 167 for (i = 3; i != 0; i--) 168 { 169 y += *(pt_table++); 170 y = fxp_mul32_Q28(y, xx); 171 y += *(pt_table++); 172 y = fxp_mul32_Q28(y, xx); 173 } 174 y += *(pt_table++); 175 y = fxp_mul32_Q28(y, xx) + *(pt_table++); 176 177 if (nn >= 0) 178 { 179 if (nn&1) 180 { 181 y = fxp_mul32_Q29(y, Q_fmt(1.41421356237310F)); 182 result->shift_factor = (nn >> 1) - 28; 183 } 184 else 185 { 186 result->shift_factor = (nn >> 1) - 29; 187 } 188 } 189 else 190 { 191 if (nn&1) 192 { 193 y = fxp_mul32_Q28(y, Q_fmt(0.70710678118655F)); 194 } 195 196 result->shift_factor = -((-nn) >> 1) - 29; 197 } 198 199 result->root = y; 200 201 } 202 else 203 { 204 result->root = 0; 205 result->shift_factor = 0; 206 } 207 208 } 209 210 sqrt_cache[2] = result->root; 211 sqrt_cache[3] = result->shift_factor; 212 213 } 214 215 216 #endif 217 218 219
