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