CMSIS DSP library
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cmsis_dsp/FastMathFunctions/arm_cos_q31.c@5:3762170b6d4d, 2015-11-20 (annotated)
- Committer:
- mbed_official
- Date:
- Fri Nov 20 08:45:18 2015 +0000
- Revision:
- 5:3762170b6d4d
- Parent:
- 3:7a284390b0ce
Synchronized with git revision 2eb940b9a73af188d3004a2575fdfbb05febe62b
Full URL: https://github.com/mbedmicro/mbed/commit/2eb940b9a73af188d3004a2575fdfbb05febe62b/
Added option to build rpc library. closes #1426
Who changed what in which revision?
User | Revision | Line number | New contents of line |
---|---|---|---|
mbed_official | 5:3762170b6d4d | 1 | /* ---------------------------------------------------------------------- |
mbed_official | 5:3762170b6d4d | 2 | * Copyright (C) 2010-2014 ARM Limited. All rights reserved. |
mbed_official | 5:3762170b6d4d | 3 | * |
mbed_official | 5:3762170b6d4d | 4 | * $Date: 07. September 2015 |
mbed_official | 5:3762170b6d4d | 5 | * $Revision: V.1.4.5 a |
mbed_official | 5:3762170b6d4d | 6 | * |
mbed_official | 5:3762170b6d4d | 7 | * Project: CMSIS DSP Library |
mbed_official | 5:3762170b6d4d | 8 | * Title: arm_cos_q31.c |
mbed_official | 5:3762170b6d4d | 9 | * |
mbed_official | 5:3762170b6d4d | 10 | * Description: Fast cosine calculation for Q31 values. |
mbed_official | 5:3762170b6d4d | 11 | * |
emilmont | 1:fdd22bb7aa52 | 12 | * Target Processor: Cortex-M4/Cortex-M3/Cortex-M0 |
mbed_official | 5:3762170b6d4d | 13 | * |
mbed_official | 5:3762170b6d4d | 14 | * Redistribution and use in source and binary forms, with or without |
mbed_official | 3:7a284390b0ce | 15 | * modification, are permitted provided that the following conditions |
mbed_official | 3:7a284390b0ce | 16 | * are met: |
mbed_official | 3:7a284390b0ce | 17 | * - Redistributions of source code must retain the above copyright |
mbed_official | 3:7a284390b0ce | 18 | * notice, this list of conditions and the following disclaimer. |
mbed_official | 3:7a284390b0ce | 19 | * - Redistributions in binary form must reproduce the above copyright |
mbed_official | 3:7a284390b0ce | 20 | * notice, this list of conditions and the following disclaimer in |
mbed_official | 5:3762170b6d4d | 21 | * the documentation and/or other materials provided with the |
mbed_official | 3:7a284390b0ce | 22 | * distribution. |
mbed_official | 3:7a284390b0ce | 23 | * - Neither the name of ARM LIMITED nor the names of its contributors |
mbed_official | 3:7a284390b0ce | 24 | * may be used to endorse or promote products derived from this |
mbed_official | 3:7a284390b0ce | 25 | * software without specific prior written permission. |
mbed_official | 3:7a284390b0ce | 26 | * |
mbed_official | 3:7a284390b0ce | 27 | * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS |
mbed_official | 3:7a284390b0ce | 28 | * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT |
mbed_official | 3:7a284390b0ce | 29 | * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS |
mbed_official | 5:3762170b6d4d | 30 | * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE |
mbed_official | 3:7a284390b0ce | 31 | * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, |
mbed_official | 3:7a284390b0ce | 32 | * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, |
mbed_official | 3:7a284390b0ce | 33 | * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; |
mbed_official | 3:7a284390b0ce | 34 | * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER |
mbed_official | 3:7a284390b0ce | 35 | * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT |
mbed_official | 3:7a284390b0ce | 36 | * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN |
mbed_official | 3:7a284390b0ce | 37 | * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE |
mbed_official | 5:3762170b6d4d | 38 | * POSSIBILITY OF SUCH DAMAGE. |
emilmont | 1:fdd22bb7aa52 | 39 | * -------------------------------------------------------------------- */ |
emilmont | 1:fdd22bb7aa52 | 40 | |
emilmont | 1:fdd22bb7aa52 | 41 | #include "arm_math.h" |
mbed_official | 5:3762170b6d4d | 42 | #include "arm_common_tables.h" |
emilmont | 1:fdd22bb7aa52 | 43 | |
mbed_official | 5:3762170b6d4d | 44 | /** |
mbed_official | 5:3762170b6d4d | 45 | * @ingroup groupFastMath |
emilmont | 1:fdd22bb7aa52 | 46 | */ |
emilmont | 1:fdd22bb7aa52 | 47 | |
mbed_official | 5:3762170b6d4d | 48 | /** |
mbed_official | 5:3762170b6d4d | 49 | * @addtogroup cos |
mbed_official | 5:3762170b6d4d | 50 | * @{ |
mbed_official | 5:3762170b6d4d | 51 | */ |
emilmont | 1:fdd22bb7aa52 | 52 | |
mbed_official | 5:3762170b6d4d | 53 | /** |
mbed_official | 5:3762170b6d4d | 54 | * @brief Fast approximation to the trigonometric cosine function for Q31 data. |
mbed_official | 5:3762170b6d4d | 55 | * @param[in] x Scaled input value in radians. |
mbed_official | 5:3762170b6d4d | 56 | * @return cos(x). |
mbed_official | 5:3762170b6d4d | 57 | * |
mbed_official | 3:7a284390b0ce | 58 | * The Q31 input value is in the range [0 +0.9999] and is mapped to a radian |
mbed_official | 3:7a284390b0ce | 59 | * value in the range [0 2*pi). |
emilmont | 1:fdd22bb7aa52 | 60 | */ |
emilmont | 1:fdd22bb7aa52 | 61 | |
emilmont | 1:fdd22bb7aa52 | 62 | q31_t arm_cos_q31( |
emilmont | 1:fdd22bb7aa52 | 63 | q31_t x) |
emilmont | 1:fdd22bb7aa52 | 64 | { |
mbed_official | 5:3762170b6d4d | 65 | q31_t cosVal; /* Temporary variables for input, output */ |
mbed_official | 5:3762170b6d4d | 66 | int32_t index; /* Index variables */ |
mbed_official | 5:3762170b6d4d | 67 | q31_t a, b; /* Four nearest output values */ |
mbed_official | 5:3762170b6d4d | 68 | q31_t fract; /* Temporary values for fractional values */ |
emilmont | 1:fdd22bb7aa52 | 69 | |
mbed_official | 5:3762170b6d4d | 70 | /* add 0.25 (pi/2) to read sine table */ |
mbed_official | 5:3762170b6d4d | 71 | x = (uint32_t)x + 0x20000000; |
mbed_official | 5:3762170b6d4d | 72 | if(x < 0) |
mbed_official | 5:3762170b6d4d | 73 | { /* convert negative numbers to corresponding positive ones */ |
mbed_official | 5:3762170b6d4d | 74 | x = (uint32_t)x + 0x80000000; |
emilmont | 1:fdd22bb7aa52 | 75 | } |
emilmont | 1:fdd22bb7aa52 | 76 | |
mbed_official | 5:3762170b6d4d | 77 | /* Calculate the nearest index */ |
mbed_official | 5:3762170b6d4d | 78 | index = (uint32_t)x >> FAST_MATH_Q31_SHIFT; |
emilmont | 1:fdd22bb7aa52 | 79 | |
mbed_official | 5:3762170b6d4d | 80 | /* Calculation of fractional value */ |
mbed_official | 5:3762170b6d4d | 81 | fract = (x - (index << FAST_MATH_Q31_SHIFT)) << 9; |
emilmont | 1:fdd22bb7aa52 | 82 | |
mbed_official | 5:3762170b6d4d | 83 | /* Read two nearest values of input value from the sin table */ |
mbed_official | 5:3762170b6d4d | 84 | a = sinTable_q31[index]; |
mbed_official | 5:3762170b6d4d | 85 | b = sinTable_q31[index+1]; |
emilmont | 1:fdd22bb7aa52 | 86 | |
mbed_official | 5:3762170b6d4d | 87 | /* Linear interpolation process */ |
mbed_official | 5:3762170b6d4d | 88 | cosVal = (q63_t)(0x80000000-fract)*a >> 32; |
mbed_official | 5:3762170b6d4d | 89 | cosVal = (q31_t)((((q63_t)cosVal << 32) + ((q63_t)fract*b)) >> 32); |
emilmont | 1:fdd22bb7aa52 | 90 | |
mbed_official | 5:3762170b6d4d | 91 | return cosVal << 1; |
emilmont | 1:fdd22bb7aa52 | 92 | } |
emilmont | 1:fdd22bb7aa52 | 93 | |
mbed_official | 5:3762170b6d4d | 94 | /** |
mbed_official | 5:3762170b6d4d | 95 | * @} end of cos group |
emilmont | 1:fdd22bb7aa52 | 96 | */ |