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