Eli Hughes / CMSIS_DSP_401

V4.0.1 of the ARM CMSIS DSP libraries. Note that arm_bitreversal2.s, arm_cfft_f32.c and arm_rfft_fast_f32.c had to be removed. arm_bitreversal2.s will not assemble with the online tools. So, the fast f32 FFT functions are not yet available. All the other FFT functions are available.

Dependents:   MPU9150_Example fir_f32 fir_f32 MPU9150_nucleo_noni2cdev ... more

FastMathFunctions/arm_sqrt_q15.c@0:3d9c67d97d6f, 2014-07-28 (annotated)

Committer:
emh203
Date:
Mon Jul 28 15:03:15 2014 +0000
Revision:
0:3d9c67d97d6f
1st working commit.   Had to remove arm_bitreversal2.s     arm_cfft_f32.c and arm_rfft_fast_f32.c.    The .s will not assemble.      For now I removed these functions so we could at least have a library for the other functions.

Who changed what in which revision?

UserRevisionLine numberNew contents of line
emh203 0:3d9c67d97d6f 1 /* ----------------------------------------------------------------------
emh203 0:3d9c67d97d6f 2 * Copyright (C) 2010-2014 ARM Limited. All rights reserved.
emh203 0:3d9c67d97d6f 3 *
emh203 0:3d9c67d97d6f 4 * $Date: 12. March 2014
emh203 0:3d9c67d97d6f 5 * $Revision: V1.4.3
emh203 0:3d9c67d97d6f 6 *
emh203 0:3d9c67d97d6f 7 * Project: CMSIS DSP Library
emh203 0:3d9c67d97d6f 8 * Title: arm_sqrt_q15.c
emh203 0:3d9c67d97d6f 9 *
emh203 0:3d9c67d97d6f 10 * Description: Q15 square root function.
emh203 0:3d9c67d97d6f 11 *
emh203 0:3d9c67d97d6f 12 * Target Processor: Cortex-M4/Cortex-M3/Cortex-M0
emh203 0:3d9c67d97d6f 13 *
emh203 0:3d9c67d97d6f 14 * Redistribution and use in source and binary forms, with or without
emh203 0:3d9c67d97d6f 15 * modification, are permitted provided that the following conditions
emh203 0:3d9c67d97d6f 16 * are met:
emh203 0:3d9c67d97d6f 17 * - Redistributions of source code must retain the above copyright
emh203 0:3d9c67d97d6f 18 * notice, this list of conditions and the following disclaimer.
emh203 0:3d9c67d97d6f 19 * - Redistributions in binary form must reproduce the above copyright
emh203 0:3d9c67d97d6f 20 * notice, this list of conditions and the following disclaimer in
emh203 0:3d9c67d97d6f 21 * the documentation and/or other materials provided with the
emh203 0:3d9c67d97d6f 22 * distribution.
emh203 0:3d9c67d97d6f 23 * - Neither the name of ARM LIMITED nor the names of its contributors
emh203 0:3d9c67d97d6f 24 * may be used to endorse or promote products derived from this
emh203 0:3d9c67d97d6f 25 * software without specific prior written permission.
emh203 0:3d9c67d97d6f 26 *
emh203 0:3d9c67d97d6f 27 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
emh203 0:3d9c67d97d6f 28 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
emh203 0:3d9c67d97d6f 29 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
emh203 0:3d9c67d97d6f 30 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
emh203 0:3d9c67d97d6f 31 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
emh203 0:3d9c67d97d6f 32 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
emh203 0:3d9c67d97d6f 33 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
emh203 0:3d9c67d97d6f 34 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
emh203 0:3d9c67d97d6f 35 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
emh203 0:3d9c67d97d6f 36 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
emh203 0:3d9c67d97d6f 37 * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
emh203 0:3d9c67d97d6f 38 * POSSIBILITY OF SUCH DAMAGE.
emh203 0:3d9c67d97d6f 39 * -------------------------------------------------------------------- */
emh203 0:3d9c67d97d6f 40 #include "arm_math.h"
emh203 0:3d9c67d97d6f 41 #include "arm_common_tables.h"
emh203 0:3d9c67d97d6f 42
emh203 0:3d9c67d97d6f 43
emh203 0:3d9c67d97d6f 44 /**
emh203 0:3d9c67d97d6f 45 * @ingroup groupFastMath
emh203 0:3d9c67d97d6f 46 */
emh203 0:3d9c67d97d6f 47
emh203 0:3d9c67d97d6f 48 /**
emh203 0:3d9c67d97d6f 49 * @addtogroup SQRT
emh203 0:3d9c67d97d6f 50 * @{
emh203 0:3d9c67d97d6f 51 */
emh203 0:3d9c67d97d6f 52
emh203 0:3d9c67d97d6f 53 /**
emh203 0:3d9c67d97d6f 54 * @brief Q15 square root function.
emh203 0:3d9c67d97d6f 55 * @param[in] in input value. The range of the input value is [0 +1) or 0x0000 to 0x7FFF.
emh203 0:3d9c67d97d6f 56 * @param[out] *pOut square root of input value.
emh203 0:3d9c67d97d6f 57 * @return The function returns ARM_MATH_SUCCESS if the input value is positive
emh203 0:3d9c67d97d6f 58 * and ARM_MATH_ARGUMENT_ERROR if the input is negative. For
emh203 0:3d9c67d97d6f 59 * negative inputs, the function returns *pOut = 0.
emh203 0:3d9c67d97d6f 60 */
emh203 0:3d9c67d97d6f 61
emh203 0:3d9c67d97d6f 62 arm_status arm_sqrt_q15(
emh203 0:3d9c67d97d6f 63 q15_t in,
emh203 0:3d9c67d97d6f 64 q15_t * pOut)
emh203 0:3d9c67d97d6f 65 {
emh203 0:3d9c67d97d6f 66 q15_t number, temp1, var1, signBits1, half;
emh203 0:3d9c67d97d6f 67 q31_t bits_val1;
emh203 0:3d9c67d97d6f 68 float32_t temp_float1;
emh203 0:3d9c67d97d6f 69 union
emh203 0:3d9c67d97d6f 70 {
emh203 0:3d9c67d97d6f 71 q31_t fracval;
emh203 0:3d9c67d97d6f 72 float32_t floatval;
emh203 0:3d9c67d97d6f 73 } tempconv;
emh203 0:3d9c67d97d6f 74
emh203 0:3d9c67d97d6f 75 number = in;
emh203 0:3d9c67d97d6f 76
emh203 0:3d9c67d97d6f 77 /* If the input is a positive number then compute the signBits. */
emh203 0:3d9c67d97d6f 78 if(number > 0)
emh203 0:3d9c67d97d6f 79 {
emh203 0:3d9c67d97d6f 80 signBits1 = __CLZ(number) - 17;
emh203 0:3d9c67d97d6f 81
emh203 0:3d9c67d97d6f 82 /* Shift by the number of signBits1 */
emh203 0:3d9c67d97d6f 83 if((signBits1 % 2) == 0)
emh203 0:3d9c67d97d6f 84 {
emh203 0:3d9c67d97d6f 85 number = number << signBits1;
emh203 0:3d9c67d97d6f 86 }
emh203 0:3d9c67d97d6f 87 else
emh203 0:3d9c67d97d6f 88 {
emh203 0:3d9c67d97d6f 89 number = number << (signBits1 - 1);
emh203 0:3d9c67d97d6f 90 }
emh203 0:3d9c67d97d6f 91
emh203 0:3d9c67d97d6f 92 /* Calculate half value of the number */
emh203 0:3d9c67d97d6f 93 half = number >> 1;
emh203 0:3d9c67d97d6f 94 /* Store the number for later use */
emh203 0:3d9c67d97d6f 95 temp1 = number;
emh203 0:3d9c67d97d6f 96
emh203 0:3d9c67d97d6f 97 /*Convert to float */
emh203 0:3d9c67d97d6f 98 temp_float1 = number * 3.051757812500000e-005f;
emh203 0:3d9c67d97d6f 99 /*Store as integer */
emh203 0:3d9c67d97d6f 100 tempconv.floatval = temp_float1;
emh203 0:3d9c67d97d6f 101 bits_val1 = tempconv.fracval;
emh203 0:3d9c67d97d6f 102 /* Subtract the shifted value from the magic number to give intial guess */
emh203 0:3d9c67d97d6f 103 bits_val1 = 0x5f3759df - (bits_val1 >> 1); // gives initial guess
emh203 0:3d9c67d97d6f 104 /* Store as float */
emh203 0:3d9c67d97d6f 105 tempconv.fracval = bits_val1;
emh203 0:3d9c67d97d6f 106 temp_float1 = tempconv.floatval;
emh203 0:3d9c67d97d6f 107 /* Convert to integer format */
emh203 0:3d9c67d97d6f 108 var1 = (q31_t) (temp_float1 * 16384);
emh203 0:3d9c67d97d6f 109
emh203 0:3d9c67d97d6f 110 /* 1st iteration */
emh203 0:3d9c67d97d6f 111 var1 = ((q15_t) ((q31_t) var1 * (0x3000 -
emh203 0:3d9c67d97d6f 112 ((q15_t)
emh203 0:3d9c67d97d6f 113 ((((q15_t)
emh203 0:3d9c67d97d6f 114 (((q31_t) var1 * var1) >> 15)) *
emh203 0:3d9c67d97d6f 115 (q31_t) half) >> 15))) >> 15)) << 2;
emh203 0:3d9c67d97d6f 116 /* 2nd iteration */
emh203 0:3d9c67d97d6f 117 var1 = ((q15_t) ((q31_t) var1 * (0x3000 -
emh203 0:3d9c67d97d6f 118 ((q15_t)
emh203 0:3d9c67d97d6f 119 ((((q15_t)
emh203 0:3d9c67d97d6f 120 (((q31_t) var1 * var1) >> 15)) *
emh203 0:3d9c67d97d6f 121 (q31_t) half) >> 15))) >> 15)) << 2;
emh203 0:3d9c67d97d6f 122 /* 3rd iteration */
emh203 0:3d9c67d97d6f 123 var1 = ((q15_t) ((q31_t) var1 * (0x3000 -
emh203 0:3d9c67d97d6f 124 ((q15_t)
emh203 0:3d9c67d97d6f 125 ((((q15_t)
emh203 0:3d9c67d97d6f 126 (((q31_t) var1 * var1) >> 15)) *
emh203 0:3d9c67d97d6f 127 (q31_t) half) >> 15))) >> 15)) << 2;
emh203 0:3d9c67d97d6f 128
emh203 0:3d9c67d97d6f 129 /* Multiply the inverse square root with the original value */
emh203 0:3d9c67d97d6f 130 var1 = ((q15_t) (((q31_t) temp1 * var1) >> 15)) << 1;
emh203 0:3d9c67d97d6f 131
emh203 0:3d9c67d97d6f 132 /* Shift the output down accordingly */
emh203 0:3d9c67d97d6f 133 if((signBits1 % 2) == 0)
emh203 0:3d9c67d97d6f 134 {
emh203 0:3d9c67d97d6f 135 var1 = var1 >> (signBits1 / 2);
emh203 0:3d9c67d97d6f 136 }
emh203 0:3d9c67d97d6f 137 else
emh203 0:3d9c67d97d6f 138 {
emh203 0:3d9c67d97d6f 139 var1 = var1 >> ((signBits1 - 1) / 2);
emh203 0:3d9c67d97d6f 140 }
emh203 0:3d9c67d97d6f 141 *pOut = var1;
emh203 0:3d9c67d97d6f 142
emh203 0:3d9c67d97d6f 143 return (ARM_MATH_SUCCESS);
emh203 0:3d9c67d97d6f 144 }
emh203 0:3d9c67d97d6f 145 /* If the number is a negative number then store zero as its square root value */
emh203 0:3d9c67d97d6f 146 else
emh203 0:3d9c67d97d6f 147 {
emh203 0:3d9c67d97d6f 148 *pOut = 0;
emh203 0:3d9c67d97d6f 149 return (ARM_MATH_ARGUMENT_ERROR);
emh203 0:3d9c67d97d6f 150 }
emh203 0:3d9c67d97d6f 151 }
emh203 0:3d9c67d97d6f 152
emh203 0:3d9c67d97d6f 153 /**
emh203 0:3d9c67d97d6f 154 * @} end of SQRT group
emh203 0:3d9c67d97d6f 155 */