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| 2 | mjames | 1 | /* ---------------------------------------------------------------------- |
| 2 | * Copyright (C) 2010-2014 ARM Limited. All rights reserved. |
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| 3 | * |
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| 4 | * $Date: 19. March 2015 |
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| 5 | * $Revision: V.1.4.5 |
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| 6 | * |
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| 7 | * Project: CMSIS DSP Library |
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| 8 | * Title: arm_scale_f32.c |
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| 9 | * |
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| 10 | * Description: Multiplies a floating-point vector by a scalar. |
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| 11 | * |
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| 12 | * Target Processor: Cortex-M4/Cortex-M3/Cortex-M0 |
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| 13 | * |
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| 14 | * Redistribution and use in source and binary forms, with or without |
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| 15 | * modification, are permitted provided that the following conditions |
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| 16 | * are met: |
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| 17 | * - Redistributions of source code must retain the above copyright |
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| 18 | * notice, this list of conditions and the following disclaimer. |
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| 19 | * - Redistributions in binary form must reproduce the above copyright |
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| 20 | * notice, this list of conditions and the following disclaimer in |
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| 21 | * the documentation and/or other materials provided with the |
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| 22 | * distribution. |
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| 23 | * - Neither the name of ARM LIMITED nor the names of its contributors |
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| 24 | * may be used to endorse or promote products derived from this |
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| 25 | * software without specific prior written permission. |
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| 26 | * |
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| 27 | * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS |
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| 28 | * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT |
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| 29 | * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS |
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| 30 | * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE |
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| 31 | * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, |
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| 32 | * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, |
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| 33 | * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; |
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| 34 | * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER |
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| 35 | * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT |
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| 36 | * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN |
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| 37 | * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE |
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| 38 | * POSSIBILITY OF SUCH DAMAGE. |
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| 39 | * ---------------------------------------------------------------------------- */ |
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| 40 | |||
| 41 | #include "arm_math.h" |
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| 42 | |||
| 43 | /** |
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| 44 | * @ingroup groupMath |
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| 45 | */ |
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| 46 | |||
| 47 | /** |
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| 48 | * @defgroup scale Vector Scale |
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| 49 | * |
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| 50 | * Multiply a vector by a scalar value. For floating-point data, the algorithm used is: |
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| 51 | * |
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| 52 | * <pre> |
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| 53 | * pDst[n] = pSrc[n] * scale, 0 <= n < blockSize. |
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| 54 | * </pre> |
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| 55 | * |
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| 56 | * In the fixed-point Q7, Q15, and Q31 functions, <code>scale</code> is represented by |
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| 57 | * a fractional multiplication <code>scaleFract</code> and an arithmetic shift <code>shift</code>. |
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| 58 | * The shift allows the gain of the scaling operation to exceed 1.0. |
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| 59 | * The algorithm used with fixed-point data is: |
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| 60 | * |
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| 61 | * <pre> |
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| 62 | * pDst[n] = (pSrc[n] * scaleFract) << shift, 0 <= n < blockSize. |
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| 63 | * </pre> |
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| 64 | * |
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| 65 | * The overall scale factor applied to the fixed-point data is |
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| 66 | * <pre> |
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| 67 | * scale = scaleFract * 2^shift. |
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| 68 | * </pre> |
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| 69 | * |
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| 70 | * The functions support in-place computation allowing the source and destination |
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| 71 | * pointers to reference the same memory buffer. |
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| 72 | */ |
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| 73 | |||
| 74 | /** |
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| 75 | * @addtogroup scale |
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| 76 | * @{ |
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| 77 | */ |
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| 78 | |||
| 79 | /** |
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| 80 | * @brief Multiplies a floating-point vector by a scalar. |
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| 81 | * @param[in] *pSrc points to the input vector |
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| 82 | * @param[in] scale scale factor to be applied |
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| 83 | * @param[out] *pDst points to the output vector |
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| 84 | * @param[in] blockSize number of samples in the vector |
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| 85 | * @return none. |
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| 86 | */ |
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| 87 | |||
| 88 | |||
| 89 | void arm_scale_f32( |
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| 90 | float32_t * pSrc, |
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| 91 | float32_t scale, |
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| 92 | float32_t * pDst, |
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| 93 | uint32_t blockSize) |
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| 94 | { |
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| 95 | uint32_t blkCnt; /* loop counter */ |
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| 96 | #ifndef ARM_MATH_CM0_FAMILY |
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| 97 | |||
| 98 | /* Run the below code for Cortex-M4 and Cortex-M3 */ |
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| 99 | float32_t in1, in2, in3, in4; /* temporary variabels */ |
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| 100 | |||
| 101 | /*loop Unrolling */ |
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| 102 | blkCnt = blockSize >> 2u; |
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| 103 | |||
| 104 | /* First part of the processing with loop unrolling. Compute 4 outputs at a time. |
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| 105 | ** a second loop below computes the remaining 1 to 3 samples. */ |
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| 106 | while(blkCnt > 0u) |
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| 107 | { |
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| 108 | /* C = A * scale */ |
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| 109 | /* Scale the input and then store the results in the destination buffer. */ |
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| 110 | /* read input samples from source */ |
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| 111 | in1 = *pSrc; |
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| 112 | in2 = *(pSrc + 1); |
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| 113 | |||
| 114 | /* multiply with scaling factor */ |
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| 115 | in1 = in1 * scale; |
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| 116 | |||
| 117 | /* read input sample from source */ |
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| 118 | in3 = *(pSrc + 2); |
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| 119 | |||
| 120 | /* multiply with scaling factor */ |
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| 121 | in2 = in2 * scale; |
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| 122 | |||
| 123 | /* read input sample from source */ |
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| 124 | in4 = *(pSrc + 3); |
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| 125 | |||
| 126 | /* multiply with scaling factor */ |
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| 127 | in3 = in3 * scale; |
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| 128 | in4 = in4 * scale; |
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| 129 | /* store the result to destination */ |
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| 130 | *pDst = in1; |
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| 131 | *(pDst + 1) = in2; |
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| 132 | *(pDst + 2) = in3; |
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| 133 | *(pDst + 3) = in4; |
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| 134 | |||
| 135 | /* update pointers to process next samples */ |
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| 136 | pSrc += 4u; |
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| 137 | pDst += 4u; |
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| 138 | |||
| 139 | /* Decrement the loop counter */ |
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| 140 | blkCnt--; |
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| 141 | } |
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| 142 | |||
| 143 | /* If the blockSize is not a multiple of 4, compute any remaining output samples here. |
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| 144 | ** No loop unrolling is used. */ |
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| 145 | blkCnt = blockSize % 0x4u; |
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| 146 | |||
| 147 | #else |
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| 148 | |||
| 149 | /* Run the below code for Cortex-M0 */ |
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| 150 | |||
| 151 | /* Initialize blkCnt with number of samples */ |
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| 152 | blkCnt = blockSize; |
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| 153 | |||
| 154 | #endif /* #ifndef ARM_MATH_CM0_FAMILY */ |
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| 155 | |||
| 156 | while(blkCnt > 0u) |
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| 157 | { |
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| 158 | /* C = A * scale */ |
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| 159 | /* Scale the input and then store the result in the destination buffer. */ |
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| 160 | *pDst++ = (*pSrc++) * scale; |
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| 161 | |||
| 162 | /* Decrement the loop counter */ |
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| 163 | blkCnt--; |
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| 164 | } |
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| 165 | } |
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| 166 | |||
| 167 | /** |
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| 168 | * @} end of scale group |
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| 169 | */ |