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The CMSIS DSP 5 library

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functions/BasicMathFunctions/arm_scale_f32.c@3:4098b9d3d571, 2018-06-21 (annotated)

Committer:
xorjoep
Date:
Thu Jun 21 11:56:27 2018 +0000
Revision:
3:4098b9d3d571
Parent:
1:24714b45cd1b 
headers is a folder not a library

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xorjoep 1:24714b45cd1b 1 /* ----------------------------------------------------------------------
xorjoep 1:24714b45cd1b 2 * Project: CMSIS DSP Library
xorjoep 1:24714b45cd1b 3 * Title: arm_scale_f32.c
xorjoep 1:24714b45cd1b 4 * Description: Multiplies a floating-point vector by a scalar
xorjoep 1:24714b45cd1b 5 *
xorjoep 1:24714b45cd1b 6 * $Date: 27. January 2017
xorjoep 1:24714b45cd1b 7 * $Revision: V.1.5.1
xorjoep 1:24714b45cd1b 8 *
xorjoep 1:24714b45cd1b 9 * Target Processor: Cortex-M cores
xorjoep 1:24714b45cd1b 10 * -------------------------------------------------------------------- */
xorjoep 1:24714b45cd1b 11 /*
xorjoep 1:24714b45cd1b 12 * Copyright (C) 2010-2017 ARM Limited or its affiliates. All rights reserved.
xorjoep 1:24714b45cd1b 13 *
xorjoep 1:24714b45cd1b 14 * SPDX-License-Identifier: Apache-2.0
xorjoep 1:24714b45cd1b 15 *
xorjoep 1:24714b45cd1b 16 * Licensed under the Apache License, Version 2.0 (the License); you may
xorjoep 1:24714b45cd1b 17 * not use this file except in compliance with the License.
xorjoep 1:24714b45cd1b 18 * You may obtain a copy of the License at
xorjoep 1:24714b45cd1b 19 *
xorjoep 1:24714b45cd1b 20 * www.apache.org/licenses/LICENSE-2.0
xorjoep 1:24714b45cd1b 21 *
xorjoep 1:24714b45cd1b 22 * Unless required by applicable law or agreed to in writing, software
xorjoep 1:24714b45cd1b 23 * distributed under the License is distributed on an AS IS BASIS, WITHOUT
xorjoep 1:24714b45cd1b 24 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
xorjoep 1:24714b45cd1b 25 * See the License for the specific language governing permissions and
xorjoep 1:24714b45cd1b 26 * limitations under the License.
xorjoep 1:24714b45cd1b 27 */
xorjoep 1:24714b45cd1b 28
xorjoep 1:24714b45cd1b 29 #include "arm_math.h"
xorjoep 1:24714b45cd1b 30
xorjoep 1:24714b45cd1b 31 /**
xorjoep 1:24714b45cd1b 32 * @ingroup groupMath
xorjoep 1:24714b45cd1b 33 */
xorjoep 1:24714b45cd1b 34
xorjoep 1:24714b45cd1b 35 /**
xorjoep 1:24714b45cd1b 36 * @defgroup scale Vector Scale
xorjoep 1:24714b45cd1b 37 *
xorjoep 1:24714b45cd1b 38 * Multiply a vector by a scalar value. For floating-point data, the algorithm used is:
xorjoep 1:24714b45cd1b 39 *
xorjoep 1:24714b45cd1b 40 * <pre>
xorjoep 1:24714b45cd1b 41 * pDst[n] = pSrc[n] * scale, 0 <= n < blockSize.
xorjoep 1:24714b45cd1b 42 * </pre>
xorjoep 1:24714b45cd1b 43 *
xorjoep 1:24714b45cd1b 44 * In the fixed-point Q7, Q15, and Q31 functions, <code>scale</code> is represented by
xorjoep 1:24714b45cd1b 45 * a fractional multiplication <code>scaleFract</code> and an arithmetic shift <code>shift</code>.
xorjoep 1:24714b45cd1b 46 * The shift allows the gain of the scaling operation to exceed 1.0.
xorjoep 1:24714b45cd1b 47 * The algorithm used with fixed-point data is:
xorjoep 1:24714b45cd1b 48 *
xorjoep 1:24714b45cd1b 49 * <pre>
xorjoep 1:24714b45cd1b 50 * pDst[n] = (pSrc[n] * scaleFract) << shift, 0 <= n < blockSize.
xorjoep 1:24714b45cd1b 51 * </pre>
xorjoep 1:24714b45cd1b 52 *
xorjoep 1:24714b45cd1b 53 * The overall scale factor applied to the fixed-point data is
xorjoep 1:24714b45cd1b 54 * <pre>
xorjoep 1:24714b45cd1b 55 * scale = scaleFract * 2^shift.
xorjoep 1:24714b45cd1b 56 * </pre>
xorjoep 1:24714b45cd1b 57 *
xorjoep 1:24714b45cd1b 58 * The functions support in-place computation allowing the source and destination
xorjoep 1:24714b45cd1b 59 * pointers to reference the same memory buffer.
xorjoep 1:24714b45cd1b 60 */
xorjoep 1:24714b45cd1b 61
xorjoep 1:24714b45cd1b 62 /**
xorjoep 1:24714b45cd1b 63 * @addtogroup scale
xorjoep 1:24714b45cd1b 64 * @{
xorjoep 1:24714b45cd1b 65 */
xorjoep 1:24714b45cd1b 66
xorjoep 1:24714b45cd1b 67 /**
xorjoep 1:24714b45cd1b 68 * @brief Multiplies a floating-point vector by a scalar.
xorjoep 1:24714b45cd1b 69 * @param[in] *pSrc points to the input vector
xorjoep 1:24714b45cd1b 70 * @param[in] scale scale factor to be applied
xorjoep 1:24714b45cd1b 71 * @param[out] *pDst points to the output vector
xorjoep 1:24714b45cd1b 72 * @param[in] blockSize number of samples in the vector
xorjoep 1:24714b45cd1b 73 * @return none.
xorjoep 1:24714b45cd1b 74 */
xorjoep 1:24714b45cd1b 75
xorjoep 1:24714b45cd1b 76
xorjoep 1:24714b45cd1b 77 void arm_scale_f32(
xorjoep 1:24714b45cd1b 78 float32_t * pSrc,
xorjoep 1:24714b45cd1b 79 float32_t scale,
xorjoep 1:24714b45cd1b 80 float32_t * pDst,
xorjoep 1:24714b45cd1b 81 uint32_t blockSize)
xorjoep 1:24714b45cd1b 82 {
xorjoep 1:24714b45cd1b 83 uint32_t blkCnt; /* loop counter */
xorjoep 1:24714b45cd1b 84 #if defined (ARM_MATH_DSP)
xorjoep 1:24714b45cd1b 85
xorjoep 1:24714b45cd1b 86 /* Run the below code for Cortex-M4 and Cortex-M3 */
xorjoep 1:24714b45cd1b 87 float32_t in1, in2, in3, in4; /* temporary variabels */
xorjoep 1:24714b45cd1b 88
xorjoep 1:24714b45cd1b 89 /*loop Unrolling */
xorjoep 1:24714b45cd1b 90 blkCnt = blockSize >> 2U;
xorjoep 1:24714b45cd1b 91
xorjoep 1:24714b45cd1b 92 /* First part of the processing with loop unrolling. Compute 4 outputs at a time.
xorjoep 1:24714b45cd1b 93 ** a second loop below computes the remaining 1 to 3 samples. */
xorjoep 1:24714b45cd1b 94 while (blkCnt > 0U)
xorjoep 1:24714b45cd1b 95 {
xorjoep 1:24714b45cd1b 96 /* C = A * scale */
xorjoep 1:24714b45cd1b 97 /* Scale the input and then store the results in the destination buffer. */
xorjoep 1:24714b45cd1b 98 /* read input samples from source */
xorjoep 1:24714b45cd1b 99 in1 = *pSrc;
xorjoep 1:24714b45cd1b 100 in2 = *(pSrc + 1);
xorjoep 1:24714b45cd1b 101
xorjoep 1:24714b45cd1b 102 /* multiply with scaling factor */
xorjoep 1:24714b45cd1b 103 in1 = in1 * scale;
xorjoep 1:24714b45cd1b 104
xorjoep 1:24714b45cd1b 105 /* read input sample from source */
xorjoep 1:24714b45cd1b 106 in3 = *(pSrc + 2);
xorjoep 1:24714b45cd1b 107
xorjoep 1:24714b45cd1b 108 /* multiply with scaling factor */
xorjoep 1:24714b45cd1b 109 in2 = in2 * scale;
xorjoep 1:24714b45cd1b 110
xorjoep 1:24714b45cd1b 111 /* read input sample from source */
xorjoep 1:24714b45cd1b 112 in4 = *(pSrc + 3);
xorjoep 1:24714b45cd1b 113
xorjoep 1:24714b45cd1b 114 /* multiply with scaling factor */
xorjoep 1:24714b45cd1b 115 in3 = in3 * scale;
xorjoep 1:24714b45cd1b 116 in4 = in4 * scale;
xorjoep 1:24714b45cd1b 117 /* store the result to destination */
xorjoep 1:24714b45cd1b 118 *pDst = in1;
xorjoep 1:24714b45cd1b 119 *(pDst + 1) = in2;
xorjoep 1:24714b45cd1b 120 *(pDst + 2) = in3;
xorjoep 1:24714b45cd1b 121 *(pDst + 3) = in4;
xorjoep 1:24714b45cd1b 122
xorjoep 1:24714b45cd1b 123 /* update pointers to process next samples */
xorjoep 1:24714b45cd1b 124 pSrc += 4U;
xorjoep 1:24714b45cd1b 125 pDst += 4U;
xorjoep 1:24714b45cd1b 126
xorjoep 1:24714b45cd1b 127 /* Decrement the loop counter */
xorjoep 1:24714b45cd1b 128 blkCnt--;
xorjoep 1:24714b45cd1b 129 }
xorjoep 1:24714b45cd1b 130
xorjoep 1:24714b45cd1b 131 /* If the blockSize is not a multiple of 4, compute any remaining output samples here.
xorjoep 1:24714b45cd1b 132 ** No loop unrolling is used. */
xorjoep 1:24714b45cd1b 133 blkCnt = blockSize % 0x4U;
xorjoep 1:24714b45cd1b 134
xorjoep 1:24714b45cd1b 135 #else
xorjoep 1:24714b45cd1b 136
xorjoep 1:24714b45cd1b 137 /* Run the below code for Cortex-M0 */
xorjoep 1:24714b45cd1b 138
xorjoep 1:24714b45cd1b 139 /* Initialize blkCnt with number of samples */
xorjoep 1:24714b45cd1b 140 blkCnt = blockSize;
xorjoep 1:24714b45cd1b 141
xorjoep 1:24714b45cd1b 142 #endif /* #if defined (ARM_MATH_DSP) */
xorjoep 1:24714b45cd1b 143
xorjoep 1:24714b45cd1b 144 while (blkCnt > 0U)
xorjoep 1:24714b45cd1b 145 {
xorjoep 1:24714b45cd1b 146 /* C = A * scale */
xorjoep 1:24714b45cd1b 147 /* Scale the input and then store the result in the destination buffer. */
xorjoep 1:24714b45cd1b 148 *pDst++ = (*pSrc++) * scale;
xorjoep 1:24714b45cd1b 149
xorjoep 1:24714b45cd1b 150 /* Decrement the loop counter */
xorjoep 1:24714b45cd1b 151 blkCnt--;
xorjoep 1:24714b45cd1b 152 }
xorjoep 1:24714b45cd1b 153 }
xorjoep 1:24714b45cd1b 154
xorjoep 1:24714b45cd1b 155 /**
xorjoep 1:24714b45cd1b 156 * @} end of scale group
xorjoep 1:24714b45cd1b 157 */