Analog Devices / Mbed OS EVAL-CN0540-ARDZ

Dependencies:   platform_drivers LTC26X6 AD77681

CMSIS-DSP_Lib/Source/FastMathFunctions/arm_cos_f32.c@1:9dd7c64b4a64, 2021-12-06 (annotated)

Committer:
jngarlitos
Date:
Mon Dec 06 05:22:28 2021 +0000
Revision:
1:9dd7c64b4a64
EVAL-CN0540-ARDZ mbed example program Initial Commit

Who changed what in which revision?

UserRevisionLine numberNew contents of line
jngarlitos 1:9dd7c64b4a64 1 /* ----------------------------------------------------------------------
jngarlitos 1:9dd7c64b4a64 2 * Copyright (C) 2010-2014 ARM Limited. All rights reserved.
jngarlitos 1:9dd7c64b4a64 3 *
jngarlitos 1:9dd7c64b4a64 4 * $Date: 21. September 2015
jngarlitos 1:9dd7c64b4a64 5 * $Revision: V.1.4.5 a
jngarlitos 1:9dd7c64b4a64 6 *
jngarlitos 1:9dd7c64b4a64 7 * Project: CMSIS DSP Library
jngarlitos 1:9dd7c64b4a64 8 * Title: arm_cos_f32.c
jngarlitos 1:9dd7c64b4a64 9 *
jngarlitos 1:9dd7c64b4a64 10 * Description: Fast cosine calculation for floating-point values.
jngarlitos 1:9dd7c64b4a64 11 *
jngarlitos 1:9dd7c64b4a64 12 * Target Processor: Cortex-M4/Cortex-M3/Cortex-M0
jngarlitos 1:9dd7c64b4a64 13 *
jngarlitos 1:9dd7c64b4a64 14 * Redistribution and use in source and binary forms, with or without
jngarlitos 1:9dd7c64b4a64 15 * modification, are permitted provided that the following conditions
jngarlitos 1:9dd7c64b4a64 16 * are met:
jngarlitos 1:9dd7c64b4a64 17 * - Redistributions of source code must retain the above copyright
jngarlitos 1:9dd7c64b4a64 18 * notice, this list of conditions and the following disclaimer.
jngarlitos 1:9dd7c64b4a64 19 * - Redistributions in binary form must reproduce the above copyright
jngarlitos 1:9dd7c64b4a64 20 * notice, this list of conditions and the following disclaimer in
jngarlitos 1:9dd7c64b4a64 21 * the documentation and/or other materials provided with the
jngarlitos 1:9dd7c64b4a64 22 * distribution.
jngarlitos 1:9dd7c64b4a64 23 * - Neither the name of ARM LIMITED nor the names of its contributors
jngarlitos 1:9dd7c64b4a64 24 * may be used to endorse or promote products derived from this
jngarlitos 1:9dd7c64b4a64 25 * software without specific prior written permission.
jngarlitos 1:9dd7c64b4a64 26 *
jngarlitos 1:9dd7c64b4a64 27 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
jngarlitos 1:9dd7c64b4a64 28 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
jngarlitos 1:9dd7c64b4a64 29 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
jngarlitos 1:9dd7c64b4a64 30 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
jngarlitos 1:9dd7c64b4a64 31 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
jngarlitos 1:9dd7c64b4a64 32 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
jngarlitos 1:9dd7c64b4a64 33 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
jngarlitos 1:9dd7c64b4a64 34 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
jngarlitos 1:9dd7c64b4a64 35 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
jngarlitos 1:9dd7c64b4a64 36 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
jngarlitos 1:9dd7c64b4a64 37 * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
jngarlitos 1:9dd7c64b4a64 38 * POSSIBILITY OF SUCH DAMAGE.
jngarlitos 1:9dd7c64b4a64 39 * -------------------------------------------------------------------- */
jngarlitos 1:9dd7c64b4a64 40
jngarlitos 1:9dd7c64b4a64 41 #include "arm_math.h"
jngarlitos 1:9dd7c64b4a64 42 #include "arm_common_tables.h"
jngarlitos 1:9dd7c64b4a64 43 /**
jngarlitos 1:9dd7c64b4a64 44 * @ingroup groupFastMath
jngarlitos 1:9dd7c64b4a64 45 */
jngarlitos 1:9dd7c64b4a64 46
jngarlitos 1:9dd7c64b4a64 47 /**
jngarlitos 1:9dd7c64b4a64 48 * @defgroup cos Cosine
jngarlitos 1:9dd7c64b4a64 49 *
jngarlitos 1:9dd7c64b4a64 50 * Computes the trigonometric cosine function using a combination of table lookup
jngarlitos 1:9dd7c64b4a64 51 * and linear interpolation. There are separate functions for
jngarlitos 1:9dd7c64b4a64 52 * Q15, Q31, and floating-point data types.
jngarlitos 1:9dd7c64b4a64 53 * The input to the floating-point version is in radians while the
jngarlitos 1:9dd7c64b4a64 54 * fixed-point Q15 and Q31 have a scaled input with the range
jngarlitos 1:9dd7c64b4a64 55 * [0 +0.9999] mapping to [0 2*pi). The fixed-point range is chosen so that a
jngarlitos 1:9dd7c64b4a64 56 * value of 2*pi wraps around to 0.
jngarlitos 1:9dd7c64b4a64 57 *
jngarlitos 1:9dd7c64b4a64 58 * The implementation is based on table lookup using 256 values together with linear interpolation.
jngarlitos 1:9dd7c64b4a64 59 * The steps used are:
jngarlitos 1:9dd7c64b4a64 60 * -# Calculation of the nearest integer table index
jngarlitos 1:9dd7c64b4a64 61 * -# Compute the fractional portion (fract) of the table index.
jngarlitos 1:9dd7c64b4a64 62 * -# The final result equals <code>(1.0f-fract)*a + fract*b;</code>
jngarlitos 1:9dd7c64b4a64 63 *
jngarlitos 1:9dd7c64b4a64 64 * where
jngarlitos 1:9dd7c64b4a64 65 * <pre>
jngarlitos 1:9dd7c64b4a64 66 * b=Table[index+0];
jngarlitos 1:9dd7c64b4a64 67 * c=Table[index+1];
jngarlitos 1:9dd7c64b4a64 68 * </pre>
jngarlitos 1:9dd7c64b4a64 69 */
jngarlitos 1:9dd7c64b4a64 70
jngarlitos 1:9dd7c64b4a64 71 /**
jngarlitos 1:9dd7c64b4a64 72 * @addtogroup cos
jngarlitos 1:9dd7c64b4a64 73 * @{
jngarlitos 1:9dd7c64b4a64 74 */
jngarlitos 1:9dd7c64b4a64 75
jngarlitos 1:9dd7c64b4a64 76 /**
jngarlitos 1:9dd7c64b4a64 77 * @brief Fast approximation to the trigonometric cosine function for floating-point data.
jngarlitos 1:9dd7c64b4a64 78 * @param[in] x input value in radians.
jngarlitos 1:9dd7c64b4a64 79 * @return cos(x).
jngarlitos 1:9dd7c64b4a64 80 */
jngarlitos 1:9dd7c64b4a64 81
jngarlitos 1:9dd7c64b4a64 82 float32_t arm_cos_f32(
jngarlitos 1:9dd7c64b4a64 83 float32_t x)
jngarlitos 1:9dd7c64b4a64 84 {
jngarlitos 1:9dd7c64b4a64 85 float32_t cosVal, fract, in; /* Temporary variables for input, output */
jngarlitos 1:9dd7c64b4a64 86 uint16_t index; /* Index variable */
jngarlitos 1:9dd7c64b4a64 87 float32_t a, b; /* Two nearest output values */
jngarlitos 1:9dd7c64b4a64 88 int32_t n;
jngarlitos 1:9dd7c64b4a64 89 float32_t findex;
jngarlitos 1:9dd7c64b4a64 90
jngarlitos 1:9dd7c64b4a64 91 /* input x is in radians */
jngarlitos 1:9dd7c64b4a64 92 /* Scale the input to [0 1] range from [0 2*PI] , divide input by 2*pi, add 0.25 (pi/2) to read sine table */
jngarlitos 1:9dd7c64b4a64 93 in = x * 0.159154943092f + 0.25f;
jngarlitos 1:9dd7c64b4a64 94
jngarlitos 1:9dd7c64b4a64 95 /* Calculation of floor value of input */
jngarlitos 1:9dd7c64b4a64 96 n = (int32_t) in;
jngarlitos 1:9dd7c64b4a64 97
jngarlitos 1:9dd7c64b4a64 98 /* Make negative values towards -infinity */
jngarlitos 1:9dd7c64b4a64 99 if(in < 0.0f)
jngarlitos 1:9dd7c64b4a64 100 {
jngarlitos 1:9dd7c64b4a64 101 n--;
jngarlitos 1:9dd7c64b4a64 102 }
jngarlitos 1:9dd7c64b4a64 103
jngarlitos 1:9dd7c64b4a64 104 /* Map input value to [0 1] */
jngarlitos 1:9dd7c64b4a64 105 in = in - (float32_t) n;
jngarlitos 1:9dd7c64b4a64 106
jngarlitos 1:9dd7c64b4a64 107 /* Calculation of index of the table */
jngarlitos 1:9dd7c64b4a64 108 findex = (float32_t) FAST_MATH_TABLE_SIZE * in;
jngarlitos 1:9dd7c64b4a64 109 index = ((uint16_t)findex) & 0x1ff;
jngarlitos 1:9dd7c64b4a64 110
jngarlitos 1:9dd7c64b4a64 111 /* fractional value calculation */
jngarlitos 1:9dd7c64b4a64 112 fract = findex - (float32_t) index;
jngarlitos 1:9dd7c64b4a64 113
jngarlitos 1:9dd7c64b4a64 114 /* Read two nearest values of input value from the cos table */
jngarlitos 1:9dd7c64b4a64 115 a = sinTable_f32[index];
jngarlitos 1:9dd7c64b4a64 116 b = sinTable_f32[index+1];
jngarlitos 1:9dd7c64b4a64 117
jngarlitos 1:9dd7c64b4a64 118 /* Linear interpolation process */
jngarlitos 1:9dd7c64b4a64 119 cosVal = (1.0f-fract)*a + fract*b;
jngarlitos 1:9dd7c64b4a64 120
jngarlitos 1:9dd7c64b4a64 121 /* Return the output value */
jngarlitos 1:9dd7c64b4a64 122 return (cosVal);
jngarlitos 1:9dd7c64b4a64 123 }
jngarlitos 1:9dd7c64b4a64 124
jngarlitos 1:9dd7c64b4a64 125 /**
jngarlitos 1:9dd7c64b4a64 126 * @} end of cos group
jngarlitos 1:9dd7c64b4a64 127 */