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| 2 | mjames | 1 | /* ---------------------------------------------------------------------- |
| 2 | * Project: CMSIS DSP Library |
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| 3 | * Title: arm_scale_q7.c |
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| 4 | * Description: Multiplies a Q7 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 Q7 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 1.7 format. |
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| 52 | * These are multiplied to yield a 2.14 intermediate result and this is shifted with saturation to 1.7 format. |
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| 53 | */ |
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| 54 | |||
| 55 | void arm_scale_q7( |
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| 56 | q7_t * pSrc, |
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| 57 | q7_t scaleFract, |
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| 58 | int8_t shift, |
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| 59 | q7_t * pDst, |
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| 60 | uint32_t blockSize) |
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| 61 | { |
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| 62 | int8_t kShift = 7 - shift; /* shift to apply after scaling */ |
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| 63 | uint32_t blkCnt; /* loop counter */ |
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| 64 | |||
| 65 | #if defined (ARM_MATH_DSP) |
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| 66 | |||
| 67 | /* Run the below code for Cortex-M4 and Cortex-M3 */ |
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| 68 | q7_t in1, in2, in3, in4, out1, out2, out3, out4; /* Temporary variables to store input & output */ |
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| 69 | |||
| 70 | |||
| 71 | /*loop Unrolling */ |
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| 72 | blkCnt = blockSize >> 2U; |
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| 73 | |||
| 74 | |||
| 75 | /* First part of the processing with loop unrolling. Compute 4 outputs at a time. |
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| 76 | ** a second loop below computes the remaining 1 to 3 samples. */ |
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| 77 | while (blkCnt > 0U) |
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| 78 | { |
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| 79 | /* Reading 4 inputs from memory */ |
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| 80 | in1 = *pSrc++; |
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| 81 | in2 = *pSrc++; |
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| 82 | in3 = *pSrc++; |
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| 83 | in4 = *pSrc++; |
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| 84 | |||
| 85 | /* C = A * scale */ |
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| 86 | /* Scale the inputs and then store the results in the temporary variables. */ |
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| 87 | out1 = (q7_t) (__SSAT(((in1) * scaleFract) >> kShift, 8)); |
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| 88 | out2 = (q7_t) (__SSAT(((in2) * scaleFract) >> kShift, 8)); |
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| 89 | out3 = (q7_t) (__SSAT(((in3) * scaleFract) >> kShift, 8)); |
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| 90 | out4 = (q7_t) (__SSAT(((in4) * scaleFract) >> kShift, 8)); |
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| 91 | |||
| 92 | /* Packing the individual outputs into 32bit and storing in |
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| 93 | * destination buffer in single write */ |
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| 94 | *__SIMD32(pDst)++ = __PACKq7(out1, out2, out3, out4); |
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| 95 | |||
| 96 | /* Decrement the loop counter */ |
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| 97 | blkCnt--; |
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| 98 | } |
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| 99 | |||
| 100 | /* If the blockSize is not a multiple of 4, compute any remaining output samples here. |
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| 101 | ** No loop unrolling is used. */ |
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| 102 | blkCnt = blockSize % 0x4U; |
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| 103 | |||
| 104 | while (blkCnt > 0U) |
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| 105 | { |
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| 106 | /* C = A * scale */ |
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| 107 | /* Scale the input and then store the result in the destination buffer. */ |
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| 108 | *pDst++ = (q7_t) (__SSAT(((*pSrc++) * scaleFract) >> kShift, 8)); |
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| 109 | |||
| 110 | /* Decrement the loop counter */ |
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| 111 | blkCnt--; |
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| 112 | } |
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| 113 | |||
| 114 | #else |
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| 115 | |||
| 116 | /* Run the below code for Cortex-M0 */ |
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| 117 | |||
| 118 | /* Initialize blkCnt with number of samples */ |
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| 119 | blkCnt = blockSize; |
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| 120 | |||
| 121 | while (blkCnt > 0U) |
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| 122 | { |
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| 123 | /* C = A * scale */ |
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| 124 | /* Scale the input and then store the result in the destination buffer. */ |
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| 125 | *pDst++ = (q7_t) (__SSAT((((q15_t) * pSrc++ * scaleFract) >> kShift), 8)); |
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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 | #endif /* #if defined (ARM_MATH_DSP) */ |
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| 132 | |||
| 133 | } |
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| 134 | |||
| 135 | /** |
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| 136 | * @} end of scale group |
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| 137 | */ |