1 /* 2 ** Copyright 2003-2010, VisualOn, Inc. 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 express or implied. 13 ** See the License for the specific language governing permissions and 14 ** limitations under the License. 15 */ 16 17 /***************************************************************************** 18 * This file contains operations in double precision. * 19 * These operations are not standard double precision operations. * 20 * They are used where single precision is not enough but the full 32 bits * 21 * precision is not necessary. For example, the function Div_32() has a * 22 * 24 bits precision which is enough for our purposes. * 23 * * 24 * The double precision numbers use a special representation: * 25 * * 26 * L_32 = hi<<16 + lo<<1 * 27 * * 28 * L_32 is a 32 bit integer. * 29 * hi and lo are 16 bit signed integers. * 30 * As the low part also contains the sign, this allows fast multiplication. * 31 * * 32 * 0x8000 0000 <= L_32 <= 0x7fff fffe. * 33 * * 34 * We will use DPF (Double Precision Format )in this file to specify * 35 * this special format. * 36 ***************************************************************************** 37 */ 38 #include "typedef.h" 39 #include "basic_op.h" 40 #include "oper_32b.h" 41 42 /***************************************************************************** 43 * * 44 * Function L_Extract() * 45 * * 46 * Extract from a 32 bit integer two 16 bit DPF. * 47 * * 48 * Arguments: * 49 * * 50 * L_32 : 32 bit integer. * 51 * 0x8000 0000 <= L_32 <= 0x7fff ffff. * 52 * hi : b16 to b31 of L_32 * 53 * lo : (L_32 - hi<<16)>>1 * 54 ***************************************************************************** 55 */ 56 57 __inline void VO_L_Extract (Word32 L_32, Word16 *hi, Word16 *lo) 58 { 59 *hi = (Word16)(L_32 >> 16); 60 *lo = (Word16)((L_32 & 0xffff) >> 1); 61 return; 62 } 63 64 /***************************************************************************** 65 * * 66 * Function L_Comp() * 67 * * 68 * Compose from two 16 bit DPF a 32 bit integer. * 69 * * 70 * L_32 = hi<<16 + lo<<1 * 71 * * 72 * Arguments: * 73 * * 74 * hi msb * 75 * lo lsf (with sign) * 76 * * 77 * Return Value : * 78 * * 79 * 32 bit long signed integer (Word32) whose value falls in the * 80 * range : 0x8000 0000 <= L_32 <= 0x7fff fff0. * 81 * * 82 ***************************************************************************** 83 */ 84 85 Word32 L_Comp (Word16 hi, Word16 lo) 86 { 87 Word32 L_32; 88 89 L_32 = L_deposit_h (hi); 90 91 return (L_mac (L_32, lo, 1)); /* = hi<<16 + lo<<1 */ 92 } 93 94 /***************************************************************************** 95 * Function Mpy_32() * 96 * * 97 * Multiply two 32 bit integers (DPF). The result is divided by 2**31 * 98 * * 99 * L_32 = (hi1*hi2)<<1 + ( (hi1*lo2)>>15 + (lo1*hi2)>>15 )<<1 * 100 * * 101 * This operation can also be viewed as the multiplication of two Q31 * 102 * number and the result is also in Q31. * 103 * * 104 * Arguments: * 105 * * 106 * hi1 hi part of first number * 107 * lo1 lo part of first number * 108 * hi2 hi part of second number * 109 * lo2 lo part of second number * 110 * * 111 ***************************************************************************** 112 */ 113 114 __inline Word32 Mpy_32 (Word16 hi1, Word16 lo1, Word16 hi2, Word16 lo2) 115 { 116 Word32 L_32; 117 L_32 = (hi1 * hi2); 118 L_32 += (hi1 * lo2) >> 15; 119 L_32 += (lo1 * hi2) >> 15; 120 L_32 <<= 1; 121 122 return (L_32); 123 } 124 125 /***************************************************************************** 126 * Function Mpy_32_16() * 127 * * 128 * Multiply a 16 bit integer by a 32 bit (DPF). The result is divided * 129 * by 2**15 * 130 * * 131 * * 132 * L_32 = (hi1*lo2)<<1 + ((lo1*lo2)>>15)<<1 * 133 * * 134 * Arguments: * 135 * * 136 * hi hi part of 32 bit number. * 137 * lo lo part of 32 bit number. * 138 * n 16 bit number. * 139 * * 140 ***************************************************************************** 141 */ 142 143 __inline Word32 Mpy_32_16 (Word16 hi, Word16 lo, Word16 n) 144 { 145 Word32 L_32; 146 147 L_32 = (hi * n)<<1; 148 L_32 += (((lo * n)>>15)<<1); 149 150 return (L_32); 151 } 152 153 /***************************************************************************** 154 * * 155 * Function Name : Div_32 * 156 * * 157 * Purpose : * 158 * Fractional integer division of two 32 bit numbers. * 159 * L_num / L_denom. * 160 * L_num and L_denom must be positive and L_num < L_denom. * 161 * L_denom = denom_hi<<16 + denom_lo<<1 * 162 * denom_hi is a normalize number. * 163 * * 164 * Inputs : * 165 * * 166 * L_num * 167 * 32 bit long signed integer (Word32) whose value falls in the * 168 * range : 0x0000 0000 < L_num < L_denom * 169 * * 170 * L_denom = denom_hi<<16 + denom_lo<<1 (DPF) * 171 * * 172 * denom_hi * 173 * 16 bit positive normalized integer whose value falls in the * 174 * range : 0x4000 < hi < 0x7fff * 175 * denom_lo * 176 * 16 bit positive integer whose value falls in the * 177 * range : 0 < lo < 0x7fff * 178 * * 179 * Return Value : * 180 * * 181 * L_div * 182 * 32 bit long signed integer (Word32) whose value falls in the * 183 * range : 0x0000 0000 <= L_div <= 0x7fff ffff. * 184 * * 185 * Algorithm: * 186 * * 187 * - find = 1/L_denom. * 188 * First approximation: approx = 1 / denom_hi * 189 * 1/L_denom = approx * (2.0 - L_denom * approx ) * 190 * * 191 * - result = L_num * (1/L_denom) * 192 ***************************************************************************** 193 */ 194 195 Word32 Div_32 (Word32 L_num, Word16 denom_hi, Word16 denom_lo) 196 { 197 Word16 approx, hi, lo, n_hi, n_lo; 198 Word32 L_32; 199 200 /* First approximation: 1 / L_denom = 1/denom_hi */ 201 202 approx = div_s ((Word16) 0x3fff, denom_hi); 203 204 /* 1/L_denom = approx * (2.0 - L_denom * approx) */ 205 206 L_32 = Mpy_32_16 (denom_hi, denom_lo, approx); 207 208 L_32 = L_sub ((Word32) 0x7fffffffL, L_32); 209 hi = L_32 >> 16; 210 lo = (L_32 & 0xffff) >> 1; 211 212 L_32 = Mpy_32_16 (hi, lo, approx); 213 214 /* L_num * (1/L_denom) */ 215 hi = L_32 >> 16; 216 lo = (L_32 & 0xffff) >> 1; 217 VO_L_Extract (L_num, &n_hi, &n_lo); 218 L_32 = Mpy_32 (n_hi, n_lo, hi, lo); 219 L_32 = L_shl2(L_32, 2); 220 221 return (L_32); 222 } 223 224
