CMSIS DSP Software Library: arm_cos_q31.c Source File Main Page Modules Data Structures Files Examples File List Globals arm_cos_q31.c Go to the documentation of this file.00001 /* ---------------------------------------------------------------------- 00002 * Copyright (C) 2010 ARM Limited. All rights reserved. 00003 * 00004 * $Date: 29. November 2010 00005 * $Revision: V1.0.3 00006 * 00007 * Project: CMSIS DSP Library 00008 * Title: arm_cos_q31.c 00009 * 00010 * Description: Fast cosine calculation for Q31 values. 00011 * 00012 * Target Processor: Cortex-M4/Cortex-M3 00013 * 00014 * Version 1.0.3 2010/11/29 00015 * Re-organized the CMSIS folders and updated documentation. 00016 * 00017 * Version 1.0.2 2010/11/11 00018 * Documentation updated. 00019 * 00020 * Version 1.0.1 2010/10/05 00021 * Production release and review comments incorporated. 00022 * 00023 * Version 1.0.0 2010/09/20 00024 * Production release and review comments incorporated. 00025 * -------------------------------------------------------------------- */ 00026 00027 #include "arm_math.h" 00028 00057 static const q31_t cosTableQ31[259] = { 00058 0x7ff62182, 0x7fffffff, 0x7ff62182, 0x7fd8878e, 0x7fa736b4, 0x7f62368f, 00059 0x7f0991c4, 0x7e9d55fc, 00060 0x7e1d93ea, 0x7d8a5f40, 0x7ce3ceb2, 0x7c29fbee, 0x7b5d039e, 0x7a7d055b, 00061 0x798a23b1, 0x78848414, 00062 0x776c4edb, 0x7641af3d, 0x7504d345, 0x73b5ebd1, 0x72552c85, 0x70e2cbc6, 00063 0x6f5f02b2, 0x6dca0d14, 00064 0x6c242960, 0x6a6d98a4, 0x68a69e81, 0x66cf8120, 0x64e88926, 0x62f201ac, 00065 0x60ec3830, 0x5ed77c8a, 00066 0x5cb420e0, 0x5a82799a, 0x5842dd54, 0x55f5a4d2, 0x539b2af0, 0x5133cc94, 00067 0x4ebfe8a5, 0x4c3fdff4, 00068 0x49b41533, 0x471cece7, 0x447acd50, 0x41ce1e65, 0x3f1749b8, 0x3c56ba70, 00069 0x398cdd32, 0x36ba2014, 00070 0x33def287, 0x30fbc54d, 0x2e110a62, 0x2b1f34eb, 0x2826b928, 0x25280c5e, 00071 0x2223a4c5, 0x1f19f97b, 00072 0x1c0b826a, 0x18f8b83c, 0x15e21445, 0x12c8106f, 0xfab272b, 0xc8bd35e, 00073 0x96a9049, 0x647d97c, 00074 0x3242abf, 0x0, 0xfcdbd541, 0xf9b82684, 0xf6956fb7, 0xf3742ca2, 0xf054d8d5, 00075 0xed37ef91, 00076 0xea1debbb, 0xe70747c4, 0xe3f47d96, 0xe0e60685, 0xdddc5b3b, 0xdad7f3a2, 00077 0xd7d946d8, 0xd4e0cb15, 00078 0xd1eef59e, 0xcf043ab3, 0xcc210d79, 0xc945dfec, 0xc67322ce, 0xc3a94590, 00079 0xc0e8b648, 0xbe31e19b, 00080 0xbb8532b0, 0xb8e31319, 0xb64beacd, 0xb3c0200c, 0xb140175b, 0xaecc336c, 00081 0xac64d510, 0xaa0a5b2e, 00082 0xa7bd22ac, 0xa57d8666, 0xa34bdf20, 0xa1288376, 0x9f13c7d0, 0x9d0dfe54, 00083 0x9b1776da, 0x99307ee0, 00084 0x9759617f, 0x9592675c, 0x93dbd6a0, 0x9235f2ec, 0x90a0fd4e, 0x8f1d343a, 00085 0x8daad37b, 0x8c4a142f, 00086 0x8afb2cbb, 0x89be50c3, 0x8893b125, 0x877b7bec, 0x8675dc4f, 0x8582faa5, 00087 0x84a2fc62, 0x83d60412, 00088 0x831c314e, 0x8275a0c0, 0x81e26c16, 0x8162aa04, 0x80f66e3c, 0x809dc971, 00089 0x8058c94c, 0x80277872, 00090 0x8009de7e, 0x80000000, 0x8009de7e, 0x80277872, 0x8058c94c, 0x809dc971, 00091 0x80f66e3c, 0x8162aa04, 00092 0x81e26c16, 0x8275a0c0, 0x831c314e, 0x83d60412, 0x84a2fc62, 0x8582faa5, 00093 0x8675dc4f, 0x877b7bec, 00094 0x8893b125, 0x89be50c3, 0x8afb2cbb, 0x8c4a142f, 0x8daad37b, 0x8f1d343a, 00095 0x90a0fd4e, 0x9235f2ec, 00096 0x93dbd6a0, 0x9592675c, 0x9759617f, 0x99307ee0, 0x9b1776da, 0x9d0dfe54, 00097 0x9f13c7d0, 0xa1288376, 00098 0xa34bdf20, 0xa57d8666, 0xa7bd22ac, 0xaa0a5b2e, 0xac64d510, 0xaecc336c, 00099 0xb140175b, 0xb3c0200c, 00100 0xb64beacd, 0xb8e31319, 0xbb8532b0, 0xbe31e19b, 0xc0e8b648, 0xc3a94590, 00101 0xc67322ce, 0xc945dfec, 00102 0xcc210d79, 0xcf043ab3, 0xd1eef59e, 0xd4e0cb15, 0xd7d946d8, 0xdad7f3a2, 00103 0xdddc5b3b, 0xe0e60685, 00104 0xe3f47d96, 0xe70747c4, 0xea1debbb, 0xed37ef91, 0xf054d8d5, 0xf3742ca2, 00105 0xf6956fb7, 0xf9b82684, 00106 0xfcdbd541, 0x0, 0x3242abf, 0x647d97c, 0x96a9049, 0xc8bd35e, 0xfab272b, 00107 0x12c8106f, 00108 0x15e21445, 0x18f8b83c, 0x1c0b826a, 0x1f19f97b, 0x2223a4c5, 0x25280c5e, 00109 0x2826b928, 0x2b1f34eb, 00110 0x2e110a62, 0x30fbc54d, 0x33def287, 0x36ba2014, 0x398cdd32, 0x3c56ba70, 00111 0x3f1749b8, 0x41ce1e65, 00112 0x447acd50, 0x471cece7, 0x49b41533, 0x4c3fdff4, 0x4ebfe8a5, 0x5133cc94, 00113 0x539b2af0, 0x55f5a4d2, 00114 0x5842dd54, 0x5a82799a, 0x5cb420e0, 0x5ed77c8a, 0x60ec3830, 0x62f201ac, 00115 0x64e88926, 0x66cf8120, 00116 0x68a69e81, 0x6a6d98a4, 0x6c242960, 0x6dca0d14, 0x6f5f02b2, 0x70e2cbc6, 00117 0x72552c85, 0x73b5ebd1, 00118 0x7504d345, 0x7641af3d, 0x776c4edb, 0x78848414, 0x798a23b1, 0x7a7d055b, 00119 0x7b5d039e, 0x7c29fbee, 00120 0x7ce3ceb2, 0x7d8a5f40, 0x7e1d93ea, 0x7e9d55fc, 0x7f0991c4, 0x7f62368f, 00121 0x7fa736b4, 0x7fd8878e, 00122 0x7ff62182, 0x7fffffff, 0x7ff62182 00123 }; 00124 00133 q31_t arm_cos_q31( 00134 q31_t x) 00135 { 00136 q31_t cosVal, fract, in, in2; /* Temporary variables for input, output */ 00137 q31_t wa, wb, wc, wd; /* Cubic interpolation coefficients */ 00138 q31_t a, b, c, d; /* Four nearest output values */ 00139 q31_t *tablePtr; /* Pointer to table */ 00140 q31_t fractCube, fractSquare; /* Temporary values for fractional value */ 00141 q31_t oneBy6 = 0x15555555; /* Fixed point value of 1/6 */ 00142 q31_t tableSpacing = TABLE_SPACING_Q31; /* Table spacing */ 00143 q31_t temp; /* Temporary variable for intermediate process */ 00144 uint32_t index; /* Index variable */ 00145 00146 in = x; 00147 00148 /* Calculate the nearest index */ 00149 index = in / tableSpacing; 00150 00151 /* Calculate the nearest value of input */ 00152 in2 = ((q31_t) index) * tableSpacing; 00153 00154 /* Calculation of fractional value */ 00155 fract = (in - in2) << 8; 00156 00157 /* fractSquare = fract * fract */ 00158 fractSquare = ((q31_t) (((q63_t) fract * fract) >> 32)); 00159 fractSquare = fractSquare << 1; 00160 00161 /* fractCube = fract * fract * fract */ 00162 fractCube = ((q31_t) (((q63_t) fractSquare * fract) >> 32)); 00163 fractCube = fractCube << 1; 00164 00165 /* Initialise table pointer */ 00166 tablePtr = (q31_t *) & cosTableQ31[index]; 00167 00168 /* Cubic interpolation process */ 00169 /* Calculation of wa */ 00170 /* wa = -(oneBy6)*fractCube + (fractSquare >> 1u) - (0x2AAAAAAA)*fract; */ 00171 wa = ((q31_t) (((q63_t) oneBy6 * fractCube) >> 32)); 00172 temp = 0x2AAAAAAA; 00173 wa = (q31_t) ((((q63_t) wa << 32) + ((q63_t) temp * fract)) >> 32); 00174 wa = -(wa << 1u); 00175 wa += (fractSquare >> 1u); 00176 00177 /* Read first nearest value of output from the cos table */ 00178 a = *tablePtr++; 00179 00180 /* cosVal = a*wa */ 00181 cosVal = ((q31_t) (((q63_t) a * wa) >> 32)); 00182 00183 /* q31(1.31) Fixed point value of 1 */ 00184 temp = 0x7FFFFFFF; 00185 00186 /* Calculation of wb */ 00187 wb = ((fractCube >> 1u) - (fractSquare + (fract >> 1u))) + temp; 00188 /* Read second nearest value of output from the cos table */ 00189 b = *tablePtr++; 00190 00191 /* cosVal += b*wb */ 00192 cosVal = (q31_t) ((((q63_t) cosVal << 32) + ((q63_t) b * (wb))) >> 32); 00193 00194 /* Calculation of wc */ 00195 wc = -fractCube + fractSquare; 00196 wc = (wc >> 1u) + fract; 00197 /* Read third nearest values of output value from the cos table */ 00198 c = *tablePtr++; 00199 00200 /* cosVal += c*wc */ 00201 cosVal = (q31_t) ((((q63_t) cosVal << 32) + ((q63_t) c * (wc))) >> 32); 00202 00203 /* Calculation of wd */ 00204 /* wd = (oneBy6)*fractCube - (oneBy6)*fract; */ 00205 fractCube = fractCube - fract; 00206 wd = ((q31_t) (((q63_t) oneBy6 * fractCube) >> 32)); 00207 wd = (wd << 1u); 00208 00209 /* Read fourth nearest value of output from the cos table */ 00210 d = *tablePtr++; 00211 00212 /* cosVal += d*wd; */ 00213 cosVal = (q31_t) ((((q63_t) cosVal << 32) + ((q63_t) d * (wd))) >> 32); 00214 00215 /* convert cosVal in 2.30 format to 1.31 format */ 00216 return (cosVal << 1u); 00217 00218 } 00219  All Data Structures Files Functions Variables Typedefs Enumerations Enumerator Defines Generated on Mon Nov 29 2010 17:19:56 for CMSIS DSP Software Library by  1.7.2