00001 /*This file is prepared for Doxygen automatic documentation generation.*/ 00015 /* Copyright (c) 2009 Atmel Corporation. All rights reserved. 00016 * 00017 * Redistribution and use in source and binary forms, with or without 00018 * modification, are permitted provided that the following conditions are met: 00019 * 00020 * 1. Redistributions of source code must retain the above copyright notice, this 00021 * list of conditions and the following disclaimer. 00022 * 00023 * 2. Redistributions in binary form must reproduce the above copyright notice, 00024 * this list of conditions and the following disclaimer in the documentation 00025 * and/or other materials provided with the distribution. 00026 * 00027 * 3. The name of Atmel may not be used to endorse or promote products derived 00028 * from this software without specific prior written permission. 00029 * 00030 * 4. This software may only be redistributed and used in connection with an Atmel 00031 * AVR product. 00032 * 00033 * THIS SOFTWARE IS PROVIDED BY ATMEL "AS IS" AND ANY EXPRESS OR IMPLIED 00034 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF 00035 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT ARE 00036 * EXPRESSLY AND SPECIFICALLY DISCLAIMED. IN NO EVENT SHALL ATMEL BE LIABLE FOR 00037 * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES 00038 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; 00039 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND 00040 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 00041 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS 00042 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE 00043 * 00044 */ 00045 00046 #include "dsp.h" 00047 00048 // Input angle from -pi/4 to pi/4 00049 dsp16_t dsp16_op_kernel_cosfix(dsp16_t angle) 00050 { 00051 // Coefficients of the 4th order Tchebychev polynom to calculate a cosine. 00052 const dsp16_t c0 = DSP16_Q(1.); 00053 const dsp16_t c2 = DSP16_Q(0.61651611328125); 00054 const dsp16_t c4 = DSP16_Q(0.1231689453125); 00055 S32 z, suma; 00056 00057 // Computation of the polynom 00058 z = (angle*angle) >> (DSP16_QB - 3); 00059 suma = c2 - ((z*c4) >> (DSP16_QB + 1)); 00060 00061 return (c0 - ((z*suma) >> DSP16_QB)); 00062 } 00063 00064 // Input angle from -pi/4 to pi/4 00065 dsp32_t dsp32_op_kernel_cosfix(dsp32_t angle) 00066 { 00067 // Coefficients of the 12th order Tchebychev polynom to calculate a cosine. 00068 const dsp32_t one = DSP32_Q(1.); 00069 const dsp32_t half = DSP32_Q(0.61685027507); //0.5*(pi^2/8); 00070 const dsp32_t C1 = DSP32_Q(0.50733903092); //(4.1666667908e-02*pi^2)*(pi^2/8); 00071 const dsp32_t C2 = DSP32_Q(-0.16690785015); //(-1.3888889225e-03*pi^4)*(pi^2/8); 00072 const dsp32_t C3 = DSP32_Q(0.02941632920); //(2.4801587642e-05*pi^6)*(pi^2/8); 00073 const dsp32_t C4 = DSP32_Q(-0.00322586085); //(-2.7557314297e-07*pi^8)*(pi^2/8); 00074 const dsp32_t C5 = DSP32_Q(0.00024118485); //(2.0875723372e-09*pi^10)*(pi^2/8); 00075 const dsp32_t C6 = DSP32_Q(-0.00001295308); //(-1.1359647598e-11*pi^12)*(pi^2/8); 00076 long long z, suma, produ; 00077 00078 // Computation of the polynom 00079 z = (long long) angle; 00080 z = (z*z) >> DSP32_QB; 00081 00082 produ = (z*C6) >> DSP32_QB; 00083 00084 suma = C5 + produ; 00085 produ = (z*suma) >> DSP32_QB; 00086 suma = C4 + produ; 00087 produ = (z*suma) >> DSP32_QB; 00088 suma = C3 + produ; 00089 produ = (z*suma) >> DSP32_QB; 00090 suma = C2 + produ; 00091 produ = (z*suma) >> DSP32_QB; 00092 suma = C1 + produ; 00093 produ = (z*suma) >> DSP32_QB; 00094 produ = z*produ; 00095 00096 return (one - (((half*z - produ)) >> (DSP32_QB - 3))); 00097 }