1 /* ----------------------------------------------------------------------
2 * Copyright (C) 2010-2014 ARM Limited. All rights reserved.
3 *
4 * $Date: 12. March 2014
5 * $Revision: V1.4.4
6 *
7 * Project: CMSIS DSP Library
8 * Title: arm_sin_f32.c
9 *
10 * Description: Fast sine calculation for floating-point values.
11 *
12 * Target Processor: Cortex-M4/Cortex-M3/Cortex-M0
13 *
14 * Redistribution and use in source and binary forms, with or without
15 * modification, are permitted provided that the following conditions
16 * are met:
17 * - Redistributions of source code must retain the above copyright
18 * notice, this list of conditions and the following disclaimer.
19 * - Redistributions in binary form must reproduce the above copyright
20 * notice, this list of conditions and the following disclaimer in
21 * the documentation and/or other materials provided with the
22 * distribution.
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
25 * software without specific prior written permission.
26 *
27 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
28 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
29 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
30 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
31 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
32 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
33 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
34 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
35 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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
38 * POSSIBILITY OF SUCH DAMAGE.
39 * -------------------------------------------------------------------- */
40
41 #include "arm_math.h"
42 #include "arm_common_tables.h"
43
44 /**
45 * @ingroup groupFastMath
46 */
47
48 /**
49 * @defgroup sin Sine
50 *
51 * Computes the trigonometric sine function using a combination of table lookup
52 * and cubic interpolation. There are separate functions for
53 * Q15, Q31, and floating-point data types.
54 * The input to the floating-point version is in radians while the
55 * fixed-point Q15 and Q31 have a scaled input with the range
56 * [0 +0.9999] mapping to [0 2*pi). The fixed-point range is chosen so that a
57 * value of 2*pi wraps around to 0.
58 *
59 * The implementation is based on table lookup using 256 values together with cubic interpolation.
60 * The steps used are:
61 * -# Calculation of the nearest integer table index
62 * -# Fetch the four table values a, b, c, and d
63 * -# Compute the fractional portion (fract) of the table index.
64 * -# Calculation of wa, wb, wc, wd
65 * -# The final result equals <code>a*wa + b*wb + c*wc + d*wd</code>
66 *
67 * where
68 * <pre>
69 * a=Table[index-1];
70 * b=Table[index+0];
71 * c=Table[index+1];
72 * d=Table[index+2];
73 * </pre>
74 * and
75 * <pre>
76 * wa=-(1/6)*fract.^3 + (1/2)*fract.^2 - (1/3)*fract;
77 * wb=(1/2)*fract.^3 - fract.^2 - (1/2)*fract + 1;
78 * wc=-(1/2)*fract.^3+(1/2)*fract.^2+fract;
79 * wd=(1/6)*fract.^3 - (1/6)*fract;
80 * </pre>
81 */
82
83 /**
84 * @addtogroup sin
85 * @{
86 */
87
88 /**
89 * @brief Fast approximation to the trigonometric sine function for floating-point data.
90 * @param[in] x input value in radians.
91 * @return sin(x).
92 */
93
arm_sin_f32(float32_t x)94 float32_t arm_sin_f32(
95 float32_t x)
96 {
97 float32_t sinVal, fract, in; /* Temporary variables for input, output */
98 uint16_t index; /* Index variable */
99 float32_t a, b; /* Two nearest output values */
100 int32_t n;
101 float32_t findex;
102
103 /* input x is in radians */
104 /* Scale the input to [0 1] range from [0 2*PI] , divide input by 2*pi */
105 in = x * 0.159154943092f;
106
107 /* Calculation of floor value of input */
108 n = (int32_t) in;
109
110 /* Make negative values towards -infinity */
111 if(x < 0.0f)
112 {
113 n--;
114 }
115
116 /* Map input value to [0 1] */
117 in = in - (float32_t) n;
118
119 /* Calculation of index of the table */
120 findex = (float32_t) FAST_MATH_TABLE_SIZE * in;
121 index = ((uint16_t)findex) & 0x1ff;
122
123 /* fractional value calculation */
124 fract = findex - (float32_t) index;
125
126 /* Read two nearest values of input value from the sin table */
127 a = sinTable_f32[index];
128 b = sinTable_f32[index+1];
129
130 /* Linear interpolation process */
131 sinVal = (1.0f-fract)*a + fract*b;
132
133 /* Return the output value */
134 return (sinVal);
135 }
136
137 /**
138 * @} end of sin group
139 */
140