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| <h1>arm_cos_q15.c</h1> </div> |
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| <a href="arm__cos__q15_8c.html">Go to the documentation of this file.</a><div class="fragment"><pre class="fragment"><a name="l00001"></a>00001 <span class="comment">/* ---------------------------------------------------------------------- </span> |
| <a name="l00002"></a>00002 <span class="comment">* Copyright (C) 2010 ARM Limited. All rights reserved. </span> |
| <a name="l00003"></a>00003 <span class="comment">* </span> |
| <a name="l00004"></a>00004 <span class="comment">* $Date: 15. July 2011 </span> |
| <a name="l00005"></a>00005 <span class="comment">* $Revision: V1.0.10 </span> |
| <a name="l00006"></a>00006 <span class="comment">* </span> |
| <a name="l00007"></a>00007 <span class="comment">* Project: CMSIS DSP Library </span> |
| <a name="l00008"></a>00008 <span class="comment">* Title: arm_cos_q15.c </span> |
| <a name="l00009"></a>00009 <span class="comment">* </span> |
| <a name="l00010"></a>00010 <span class="comment">* Description: Fast cosine calculation for Q15 values. </span> |
| <a name="l00011"></a>00011 <span class="comment">* </span> |
| <a name="l00012"></a>00012 <span class="comment">* Target Processor: Cortex-M4/Cortex-M3/Cortex-M0</span> |
| <a name="l00013"></a>00013 <span class="comment">* </span> |
| <a name="l00014"></a>00014 <span class="comment">* Version 1.0.10 2011/7/15 </span> |
| <a name="l00015"></a>00015 <span class="comment">* Big Endian support added and Merged M0 and M3/M4 Source code. </span> |
| <a name="l00016"></a>00016 <span class="comment">* </span> |
| <a name="l00017"></a>00017 <span class="comment">* Version 1.0.3 2010/11/29 </span> |
| <a name="l00018"></a>00018 <span class="comment">* Re-organized the CMSIS folders and updated documentation. </span> |
| <a name="l00019"></a>00019 <span class="comment">* </span> |
| <a name="l00020"></a>00020 <span class="comment">* Version 1.0.2 2010/11/11 </span> |
| <a name="l00021"></a>00021 <span class="comment">* Documentation updated. </span> |
| <a name="l00022"></a>00022 <span class="comment">* </span> |
| <a name="l00023"></a>00023 <span class="comment">* Version 1.0.1 2010/10/05 </span> |
| <a name="l00024"></a>00024 <span class="comment">* Production release and review comments incorporated. </span> |
| <a name="l00025"></a>00025 <span class="comment">* </span> |
| <a name="l00026"></a>00026 <span class="comment">* Version 1.0.0 2010/09/20 </span> |
| <a name="l00027"></a>00027 <span class="comment">* Production release and review comments incorporated. </span> |
| <a name="l00028"></a>00028 <span class="comment">* -------------------------------------------------------------------- */</span> |
| <a name="l00029"></a>00029 |
| <a name="l00030"></a>00030 <span class="preprocessor">#include "<a class="code" href="arm__math_8h.html">arm_math.h</a>"</span> |
| <a name="l00031"></a>00031 |
| <a name="l00060"></a><a class="code" href="group__cos.html#ga012ad965e3493ffcc6dd7f9a12569e58">00060</a> <span class="keyword">static</span> <span class="keyword">const</span> <a class="code" href="arm__math_8h.html#ab5a8fb21a5b3b983d5f54f31614052ea" title="16-bit fractional data type in 1.15 format.">q15_t</a> <a class="code" href="group__cos.html#ga012ad965e3493ffcc6dd7f9a12569e58">cosTableQ15</a>[259] = { |
| <a name="l00061"></a>00061 0x7ff6, 0x7fff, 0x7ff6, 0x7fd9, 0x7fa7, 0x7f62, 0x7f0a, 0x7e9d, |
| <a name="l00062"></a>00062 0x7e1e, 0x7d8a, 0x7ce4, 0x7c2a, 0x7b5d, 0x7a7d, 0x798a, 0x7885, |
| <a name="l00063"></a>00063 0x776c, 0x7642, 0x7505, 0x73b6, 0x7255, 0x70e3, 0x6f5f, 0x6dca, |
| <a name="l00064"></a>00064 0x6c24, 0x6a6e, 0x68a7, 0x66d0, 0x64e9, 0x62f2, 0x60ec, 0x5ed7, |
| <a name="l00065"></a>00065 0x5cb4, 0x5a82, 0x5843, 0x55f6, 0x539b, 0x5134, 0x4ec0, 0x4c40, |
| <a name="l00066"></a>00066 0x49b4, 0x471d, 0x447b, 0x41ce, 0x3f17, 0x3c57, 0x398d, 0x36ba, |
| <a name="l00067"></a>00067 0x33df, 0x30fc, 0x2e11, 0x2b1f, 0x2827, 0x2528, 0x2224, 0x1f1a, |
| <a name="l00068"></a>00068 0x1c0c, 0x18f9, 0x15e2, 0x12c8, 0xfab, 0xc8c, 0x96b, 0x648, |
| <a name="l00069"></a>00069 0x324, 0x0, 0xfcdc, 0xf9b8, 0xf695, 0xf374, 0xf055, 0xed38, |
| <a name="l00070"></a>00070 0xea1e, 0xe707, 0xe3f4, 0xe0e6, 0xdddc, 0xdad8, 0xd7d9, 0xd4e1, |
| <a name="l00071"></a>00071 0xd1ef, 0xcf04, 0xcc21, 0xc946, 0xc673, 0xc3a9, 0xc0e9, 0xbe32, |
| <a name="l00072"></a>00072 0xbb85, 0xb8e3, 0xb64c, 0xb3c0, 0xb140, 0xaecc, 0xac65, 0xaa0a, |
| <a name="l00073"></a>00073 0xa7bd, 0xa57e, 0xa34c, 0xa129, 0x9f14, 0x9d0e, 0x9b17, 0x9930, |
| <a name="l00074"></a>00074 0x9759, 0x9592, 0x93dc, 0x9236, 0x90a1, 0x8f1d, 0x8dab, 0x8c4a, |
| <a name="l00075"></a>00075 0x8afb, 0x89be, 0x8894, 0x877b, 0x8676, 0x8583, 0x84a3, 0x83d6, |
| <a name="l00076"></a>00076 0x831c, 0x8276, 0x81e2, 0x8163, 0x80f6, 0x809e, 0x8059, 0x8027, |
| <a name="l00077"></a>00077 0x800a, 0x8000, 0x800a, 0x8027, 0x8059, 0x809e, 0x80f6, 0x8163, |
| <a name="l00078"></a>00078 0x81e2, 0x8276, 0x831c, 0x83d6, 0x84a3, 0x8583, 0x8676, 0x877b, |
| <a name="l00079"></a>00079 0x8894, 0x89be, 0x8afb, 0x8c4a, 0x8dab, 0x8f1d, 0x90a1, 0x9236, |
| <a name="l00080"></a>00080 0x93dc, 0x9592, 0x9759, 0x9930, 0x9b17, 0x9d0e, 0x9f14, 0xa129, |
| <a name="l00081"></a>00081 0xa34c, 0xa57e, 0xa7bd, 0xaa0a, 0xac65, 0xaecc, 0xb140, 0xb3c0, |
| <a name="l00082"></a>00082 0xb64c, 0xb8e3, 0xbb85, 0xbe32, 0xc0e9, 0xc3a9, 0xc673, 0xc946, |
| <a name="l00083"></a>00083 0xcc21, 0xcf04, 0xd1ef, 0xd4e1, 0xd7d9, 0xdad8, 0xdddc, 0xe0e6, |
| <a name="l00084"></a>00084 0xe3f4, 0xe707, 0xea1e, 0xed38, 0xf055, 0xf374, 0xf695, 0xf9b8, |
| <a name="l00085"></a>00085 0xfcdc, 0x0, 0x324, 0x648, 0x96b, 0xc8c, 0xfab, 0x12c8, |
| <a name="l00086"></a>00086 0x15e2, 0x18f9, 0x1c0c, 0x1f1a, 0x2224, 0x2528, 0x2827, 0x2b1f, |
| <a name="l00087"></a>00087 0x2e11, 0x30fc, 0x33df, 0x36ba, 0x398d, 0x3c57, 0x3f17, 0x41ce, |
| <a name="l00088"></a>00088 0x447b, 0x471d, 0x49b4, 0x4c40, 0x4ec0, 0x5134, 0x539b, 0x55f6, |
| <a name="l00089"></a>00089 0x5843, 0x5a82, 0x5cb4, 0x5ed7, 0x60ec, 0x62f2, 0x64e9, 0x66d0, |
| <a name="l00090"></a>00090 0x68a7, 0x6a6e, 0x6c24, 0x6dca, 0x6f5f, 0x70e3, 0x7255, 0x73b6, |
| <a name="l00091"></a>00091 0x7505, 0x7642, 0x776c, 0x7885, 0x798a, 0x7a7d, 0x7b5d, 0x7c2a, |
| <a name="l00092"></a>00092 0x7ce4, 0x7d8a, 0x7e1e, 0x7e9d, 0x7f0a, 0x7f62, 0x7fa7, 0x7fd9, |
| <a name="l00093"></a>00093 0x7ff6, 0x7fff, 0x7ff6 |
| <a name="l00094"></a>00094 }; |
| <a name="l00095"></a>00095 |
| <a name="l00096"></a>00096 |
| <a name="l00105"></a><a class="code" href="group__cos.html#gadfd60c24def501638c0d5db20f4c869b">00105</a> <a class="code" href="arm__math_8h.html#ab5a8fb21a5b3b983d5f54f31614052ea" title="16-bit fractional data type in 1.15 format.">q15_t</a> <a class="code" href="group__cos.html#gadfd60c24def501638c0d5db20f4c869b" title="Fast approximation to the trigonometric cosine function for Q15 data.">arm_cos_q15</a>( |
| <a name="l00106"></a>00106 <a class="code" href="arm__math_8h.html#ab5a8fb21a5b3b983d5f54f31614052ea" title="16-bit fractional data type in 1.15 format.">q15_t</a> x) |
| <a name="l00107"></a>00107 { |
| <a name="l00108"></a>00108 <a class="code" href="arm__math_8h.html#adc89a3547f5324b7b3b95adec3806bc0" title="32-bit fractional data type in 1.31 format.">q31_t</a> cosVal; <span class="comment">/* Temporary variable for output */</span> |
| <a name="l00109"></a>00109 <a class="code" href="arm__math_8h.html#ab5a8fb21a5b3b983d5f54f31614052ea" title="16-bit fractional data type in 1.15 format.">q15_t</a> *tablePtr; <span class="comment">/* Pointer to table */</span> |
| <a name="l00110"></a>00110 <a class="code" href="arm__math_8h.html#ab5a8fb21a5b3b983d5f54f31614052ea" title="16-bit fractional data type in 1.15 format.">q15_t</a> in, in2; <span class="comment">/* Temporary variables for input */</span> |
| <a name="l00111"></a>00111 <a class="code" href="arm__math_8h.html#adc89a3547f5324b7b3b95adec3806bc0" title="32-bit fractional data type in 1.31 format.">q31_t</a> wa, wb, wc, wd; <span class="comment">/* Cubic interpolation coefficients */</span> |
| <a name="l00112"></a>00112 <a class="code" href="arm__math_8h.html#ab5a8fb21a5b3b983d5f54f31614052ea" title="16-bit fractional data type in 1.15 format.">q15_t</a> a, b, c, d; <span class="comment">/* Four nearest output values */</span> |
| <a name="l00113"></a>00113 <a class="code" href="arm__math_8h.html#ab5a8fb21a5b3b983d5f54f31614052ea" title="16-bit fractional data type in 1.15 format.">q15_t</a> fract, fractCube, fractSquare; <span class="comment">/* Variables for fractional value */</span> |
| <a name="l00114"></a>00114 <a class="code" href="arm__math_8h.html#ab5a8fb21a5b3b983d5f54f31614052ea" title="16-bit fractional data type in 1.15 format.">q15_t</a> oneBy6 = 0x1555; <span class="comment">/* Fixed point value of 1/6 */</span> |
| <a name="l00115"></a>00115 <a class="code" href="arm__math_8h.html#ab5a8fb21a5b3b983d5f54f31614052ea" title="16-bit fractional data type in 1.15 format.">q15_t</a> tableSpacing = <a class="code" href="arm__math_8h.html#a60b0142af7be007902142add27919b82">TABLE_SPACING_Q15</a>; <span class="comment">/* Table spacing */</span> |
| <a name="l00116"></a>00116 int32_t index; <span class="comment">/* Index variable */</span> |
| <a name="l00117"></a>00117 |
| <a name="l00118"></a>00118 in = x; |
| <a name="l00119"></a>00119 |
| <a name="l00120"></a>00120 <span class="comment">/* Calculate the nearest index */</span> |
| <a name="l00121"></a>00121 index = (int32_t) in / tableSpacing; |
| <a name="l00122"></a>00122 |
| <a name="l00123"></a>00123 <span class="comment">/* Calculate the nearest value of input */</span> |
| <a name="l00124"></a>00124 in2 = (<a class="code" href="arm__math_8h.html#ab5a8fb21a5b3b983d5f54f31614052ea" title="16-bit fractional data type in 1.15 format.">q15_t</a>) index *tableSpacing; |
| <a name="l00125"></a>00125 |
| <a name="l00126"></a>00126 <span class="comment">/* Calculation of fractional value */</span> |
| <a name="l00127"></a>00127 fract = (in - in2) << 8; |
| <a name="l00128"></a>00128 |
| <a name="l00129"></a>00129 <span class="comment">/* fractSquare = fract * fract */</span> |
| <a name="l00130"></a>00130 fractSquare = (<a class="code" href="arm__math_8h.html#ab5a8fb21a5b3b983d5f54f31614052ea" title="16-bit fractional data type in 1.15 format.">q15_t</a>) ((fract * fract) >> 15); |
| <a name="l00131"></a>00131 |
| <a name="l00132"></a>00132 <span class="comment">/* fractCube = fract * fract * fract */</span> |
| <a name="l00133"></a>00133 fractCube = (<a class="code" href="arm__math_8h.html#ab5a8fb21a5b3b983d5f54f31614052ea" title="16-bit fractional data type in 1.15 format.">q15_t</a>) ((fractSquare * fract) >> 15); |
| <a name="l00134"></a>00134 |
| <a name="l00135"></a>00135 <span class="comment">/* Initialise table pointer */</span> |
| <a name="l00136"></a>00136 tablePtr = (<a class="code" href="arm__math_8h.html#ab5a8fb21a5b3b983d5f54f31614052ea" title="16-bit fractional data type in 1.15 format.">q15_t</a> *) & <a class="code" href="group__cos.html#ga012ad965e3493ffcc6dd7f9a12569e58">cosTableQ15</a>[index]; |
| <a name="l00137"></a>00137 |
| <a name="l00138"></a>00138 <span class="comment">/* Cubic interpolation process */</span> |
| <a name="l00139"></a>00139 <span class="comment">/* Calculation of wa */</span> |
| <a name="l00140"></a>00140 <span class="comment">/* wa = -(oneBy6)*fractCube + (fractSquare >> 1u) - (0x2AAA)*fract; */</span> |
| <a name="l00141"></a>00141 wa = (<a class="code" href="arm__math_8h.html#adc89a3547f5324b7b3b95adec3806bc0" title="32-bit fractional data type in 1.31 format.">q31_t</a>) oneBy6 *fractCube; |
| <a name="l00142"></a>00142 wa += (<a class="code" href="arm__math_8h.html#adc89a3547f5324b7b3b95adec3806bc0" title="32-bit fractional data type in 1.31 format.">q31_t</a>) 0x2AAA *fract; |
| <a name="l00143"></a>00143 wa = -(wa >> 15); |
| <a name="l00144"></a>00144 wa += (fractSquare >> 1u); |
| <a name="l00145"></a>00145 |
| <a name="l00146"></a>00146 <span class="comment">/* Read first nearest value of output from the cos table */</span> |
| <a name="l00147"></a>00147 a = *tablePtr++; |
| <a name="l00148"></a>00148 |
| <a name="l00149"></a>00149 <span class="comment">/* cosVal = a * wa */</span> |
| <a name="l00150"></a>00150 cosVal = a * wa; |
| <a name="l00151"></a>00151 |
| <a name="l00152"></a>00152 <span class="comment">/* Calculation of wb */</span> |
| <a name="l00153"></a>00153 wb = (((fractCube >> 1u) - fractSquare) - (fract >> 1u)) + 0x7FFF; |
| <a name="l00154"></a>00154 |
| <a name="l00155"></a>00155 <span class="comment">/* Read second nearest value of output from the cos table */</span> |
| <a name="l00156"></a>00156 b = *tablePtr++; |
| <a name="l00157"></a>00157 |
| <a name="l00158"></a>00158 <span class="comment">/* cosVal += b*wb */</span> |
| <a name="l00159"></a>00159 cosVal += b * wb; |
| <a name="l00160"></a>00160 |
| <a name="l00161"></a>00161 <span class="comment">/* Calculation of wc */</span> |
| <a name="l00162"></a>00162 wc = -(<a class="code" href="arm__math_8h.html#adc89a3547f5324b7b3b95adec3806bc0" title="32-bit fractional data type in 1.31 format.">q31_t</a>) fractCube + fractSquare; |
| <a name="l00163"></a>00163 wc = (wc >> 1u) + fract; |
| <a name="l00164"></a>00164 |
| <a name="l00165"></a>00165 <span class="comment">/* Read third nearest value of output from the cos table */</span> |
| <a name="l00166"></a>00166 c = *tablePtr++; |
| <a name="l00167"></a>00167 |
| <a name="l00168"></a>00168 <span class="comment">/* cosVal += c*wc */</span> |
| <a name="l00169"></a>00169 cosVal += c * wc; |
| <a name="l00170"></a>00170 |
| <a name="l00171"></a>00171 <span class="comment">/* Calculation of wd */</span> |
| <a name="l00172"></a>00172 <span class="comment">/* wd = (oneBy6)*fractCube - (oneBy6)*fract; */</span> |
| <a name="l00173"></a>00173 fractCube = fractCube - fract; |
| <a name="l00174"></a>00174 wd = ((<a class="code" href="arm__math_8h.html#ab5a8fb21a5b3b983d5f54f31614052ea" title="16-bit fractional data type in 1.15 format.">q15_t</a>) (((<a class="code" href="arm__math_8h.html#adc89a3547f5324b7b3b95adec3806bc0" title="32-bit fractional data type in 1.31 format.">q31_t</a>) oneBy6 * fractCube) >> 15)); |
| <a name="l00175"></a>00175 |
| <a name="l00176"></a>00176 <span class="comment">/* Read fourth nearest value of output from the cos table */</span> |
| <a name="l00177"></a>00177 d = *tablePtr++; |
| <a name="l00178"></a>00178 |
| <a name="l00179"></a>00179 <span class="comment">/* cosVal += d*wd; */</span> |
| <a name="l00180"></a>00180 cosVal += d * wd; |
| <a name="l00181"></a>00181 |
| <a name="l00182"></a>00182 <span class="comment">/* Return the output value in 1.15(q15) format */</span> |
| <a name="l00183"></a>00183 <span class="keywordflow">return</span> ((<a class="code" href="arm__math_8h.html#ab5a8fb21a5b3b983d5f54f31614052ea" title="16-bit fractional data type in 1.15 format.">q15_t</a>) (cosVal >> 15u)); |
| <a name="l00184"></a>00184 |
| <a name="l00185"></a>00185 } |
| <a name="l00186"></a>00186 |
| </pre></div></div> |
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