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| 56 | mjames | 1 | /* ---------------------------------------------------------------------- |
| 2 | * Project: CMSIS DSP Library |
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| 3 | * Title: arm_scale_q15.c |
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| 4 | * Description: Multiplies a Q15 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 | * @addtogroup scale |
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| 37 | * @{ |
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| 38 | */ |
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| 39 | |||
| 40 | /** |
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| 41 | * @brief Multiplies a Q15 vector by a scalar. |
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| 42 | * @param[in] *pSrc points to the input vector |
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| 43 | * @param[in] scaleFract fractional portion of the scale value |
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| 44 | * @param[in] shift number of bits to shift the result by |
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| 45 | * @param[out] *pDst points to the output vector |
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| 46 | * @param[in] blockSize number of samples in the vector |
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| 47 | * @return none. |
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| 48 | * |
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| 49 | * <b>Scaling and Overflow Behavior:</b> |
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| 50 | * \par |
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| 51 | * The input data <code>*pSrc</code> and <code>scaleFract</code> are in 1.15 format. |
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| 52 | * These are multiplied to yield a 2.30 intermediate result and this is shifted with saturation to 1.15 format. |
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| 53 | */ |
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| 54 | |||
| 55 | |||
| 56 | void arm_scale_q15( |
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| 57 | q15_t * pSrc, |
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| 58 | q15_t scaleFract, |
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| 59 | int8_t shift, |
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| 60 | q15_t * pDst, |
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| 61 | uint32_t blockSize) |
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| 62 | { |
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| 63 | int8_t kShift = 15 - shift; /* shift to apply after scaling */ |
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| 64 | uint32_t blkCnt; /* loop counter */ |
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| 65 | |||
| 66 | #if defined (ARM_MATH_DSP) |
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| 67 | |||
| 68 | /* Run the below code for Cortex-M4 and Cortex-M3 */ |
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| 69 | q15_t in1, in2, in3, in4; |
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| 70 | q31_t inA1, inA2; /* Temporary variables */ |
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| 71 | q31_t out1, out2, out3, out4; |
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| 72 | |||
| 73 | |||
| 74 | /*loop Unrolling */ |
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| 75 | blkCnt = blockSize >> 2U; |
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| 76 | |||
| 77 | /* First part of the processing with loop unrolling. Compute 4 outputs at a time. |
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| 78 | ** a second loop below computes the remaining 1 to 3 samples. */ |
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| 79 | while (blkCnt > 0U) |
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| 80 | { |
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| 81 | /* Reading 2 inputs from memory */ |
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| 82 | inA1 = *__SIMD32(pSrc)++; |
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| 83 | inA2 = *__SIMD32(pSrc)++; |
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| 84 | |||
| 85 | /* C = A * scale */ |
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| 86 | /* Scale the inputs and then store the 2 results in the destination buffer |
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| 87 | * in single cycle by packing the outputs */ |
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| 88 | out1 = (q31_t) ((q15_t) (inA1 >> 16) * scaleFract); |
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| 89 | out2 = (q31_t) ((q15_t) inA1 * scaleFract); |
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| 90 | out3 = (q31_t) ((q15_t) (inA2 >> 16) * scaleFract); |
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| 91 | out4 = (q31_t) ((q15_t) inA2 * scaleFract); |
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| 92 | |||
| 93 | /* apply shifting */ |
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| 94 | out1 = out1 >> kShift; |
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| 95 | out2 = out2 >> kShift; |
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| 96 | out3 = out3 >> kShift; |
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| 97 | out4 = out4 >> kShift; |
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| 98 | |||
| 99 | /* saturate the output */ |
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| 100 | in1 = (q15_t) (__SSAT(out1, 16)); |
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| 101 | in2 = (q15_t) (__SSAT(out2, 16)); |
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| 102 | in3 = (q15_t) (__SSAT(out3, 16)); |
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| 103 | in4 = (q15_t) (__SSAT(out4, 16)); |
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| 104 | |||
| 105 | /* store the result to destination */ |
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| 106 | *__SIMD32(pDst)++ = __PKHBT(in2, in1, 16); |
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| 107 | *__SIMD32(pDst)++ = __PKHBT(in4, in3, 16); |
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| 108 | |||
| 109 | /* Decrement the loop counter */ |
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| 110 | blkCnt--; |
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| 111 | } |
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| 112 | |||
| 113 | /* If the blockSize is not a multiple of 4, compute any remaining output samples here. |
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| 114 | ** No loop unrolling is used. */ |
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| 115 | blkCnt = blockSize % 0x4U; |
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| 116 | |||
| 117 | while (blkCnt > 0U) |
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| 118 | { |
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| 119 | /* C = A * scale */ |
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| 120 | /* Scale the input and then store the result in the destination buffer. */ |
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| 121 | *pDst++ = (q15_t) (__SSAT(((*pSrc++) * scaleFract) >> kShift, 16)); |
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| 122 | |||
| 123 | /* Decrement the loop counter */ |
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| 124 | blkCnt--; |
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| 125 | } |
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| 126 | |||
| 127 | #else |
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| 128 | |||
| 129 | /* Run the below code for Cortex-M0 */ |
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| 130 | |||
| 131 | /* Initialize blkCnt with number of samples */ |
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| 132 | blkCnt = blockSize; |
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| 133 | |||
| 134 | while (blkCnt > 0U) |
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| 135 | { |
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| 136 | /* C = A * scale */ |
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| 137 | /* Scale the input and then store the result in the destination buffer. */ |
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| 138 | *pDst++ = (q15_t) (__SSAT(((q31_t) * pSrc++ * scaleFract) >> kShift, 16)); |
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| 139 | |||
| 140 | /* Decrement the loop counter */ |
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| 141 | blkCnt--; |
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| 142 | } |
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| 143 | |||
| 144 | #endif /* #if defined (ARM_MATH_DSP) */ |
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| 145 | |||
| 146 | } |
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| 147 | |||
| 148 | /** |
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| 149 | * @} end of scale group |
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| 150 | */ |