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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_q15.c |
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| 9 | * |
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| 10 | * Description: Multiplies a Q15 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 | * @addtogroup scale |
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| 49 | * @{ |
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| 50 | */ |
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| 51 | |||
| 52 | /** |
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| 53 | * @brief Multiplies a Q15 vector by a scalar. |
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| 54 | * @param[in] *pSrc points to the input vector |
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| 55 | * @param[in] scaleFract fractional portion of the scale value |
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| 56 | * @param[in] shift number of bits to shift the result by |
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| 57 | * @param[out] *pDst points to the output vector |
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| 58 | * @param[in] blockSize number of samples in the vector |
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| 59 | * @return none. |
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| 60 | * |
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| 61 | * <b>Scaling and Overflow Behavior:</b> |
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| 62 | * \par |
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| 63 | * The input data <code>*pSrc</code> and <code>scaleFract</code> are in 1.15 format. |
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| 64 | * These are multiplied to yield a 2.30 intermediate result and this is shifted with saturation to 1.15 format. |
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| 65 | */ |
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| 66 | |||
| 67 | |||
| 68 | void arm_scale_q15( |
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| 69 | q15_t * pSrc, |
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| 70 | q15_t scaleFract, |
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| 71 | int8_t shift, |
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| 72 | q15_t * pDst, |
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| 73 | uint32_t blockSize) |
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| 74 | { |
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| 75 | int8_t kShift = 15 - shift; /* shift to apply after scaling */ |
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| 76 | uint32_t blkCnt; /* loop counter */ |
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| 77 | |||
| 78 | #ifndef ARM_MATH_CM0_FAMILY |
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| 79 | |||
| 80 | /* Run the below code for Cortex-M4 and Cortex-M3 */ |
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| 81 | q15_t in1, in2, in3, in4; |
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| 82 | q31_t inA1, inA2; /* Temporary variables */ |
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| 83 | q31_t out1, out2, out3, out4; |
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| 84 | |||
| 85 | |||
| 86 | /*loop Unrolling */ |
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| 87 | blkCnt = blockSize >> 2u; |
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| 88 | |||
| 89 | /* First part of the processing with loop unrolling. Compute 4 outputs at a time. |
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| 90 | ** a second loop below computes the remaining 1 to 3 samples. */ |
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| 91 | while(blkCnt > 0u) |
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| 92 | { |
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| 93 | /* Reading 2 inputs from memory */ |
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| 94 | inA1 = *__SIMD32(pSrc)++; |
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| 95 | inA2 = *__SIMD32(pSrc)++; |
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| 96 | |||
| 97 | /* C = A * scale */ |
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| 98 | /* Scale the inputs and then store the 2 results in the destination buffer |
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| 99 | * in single cycle by packing the outputs */ |
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| 100 | out1 = (q31_t) ((q15_t) (inA1 >> 16) * scaleFract); |
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| 101 | out2 = (q31_t) ((q15_t) inA1 * scaleFract); |
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| 102 | out3 = (q31_t) ((q15_t) (inA2 >> 16) * scaleFract); |
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| 103 | out4 = (q31_t) ((q15_t) inA2 * scaleFract); |
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| 104 | |||
| 105 | /* apply shifting */ |
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| 106 | out1 = out1 >> kShift; |
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| 107 | out2 = out2 >> kShift; |
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| 108 | out3 = out3 >> kShift; |
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| 109 | out4 = out4 >> kShift; |
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| 110 | |||
| 111 | /* saturate the output */ |
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| 112 | in1 = (q15_t) (__SSAT(out1, 16)); |
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| 113 | in2 = (q15_t) (__SSAT(out2, 16)); |
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| 114 | in3 = (q15_t) (__SSAT(out3, 16)); |
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| 115 | in4 = (q15_t) (__SSAT(out4, 16)); |
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| 116 | |||
| 117 | /* store the result to destination */ |
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| 118 | *__SIMD32(pDst)++ = __PKHBT(in2, in1, 16); |
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| 119 | *__SIMD32(pDst)++ = __PKHBT(in4, in3, 16); |
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| 120 | |||
| 121 | /* Decrement the loop counter */ |
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| 122 | blkCnt--; |
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| 123 | } |
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| 124 | |||
| 125 | /* If the blockSize is not a multiple of 4, compute any remaining output samples here. |
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| 126 | ** No loop unrolling is used. */ |
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| 127 | blkCnt = blockSize % 0x4u; |
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| 128 | |||
| 129 | while(blkCnt > 0u) |
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| 130 | { |
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| 131 | /* C = A * scale */ |
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| 132 | /* Scale the input and then store the result in the destination buffer. */ |
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| 133 | *pDst++ = (q15_t) (__SSAT(((*pSrc++) * scaleFract) >> kShift, 16)); |
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| 134 | |||
| 135 | /* Decrement the loop counter */ |
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| 136 | blkCnt--; |
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| 137 | } |
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| 138 | |||
| 139 | #else |
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| 140 | |||
| 141 | /* Run the below code for Cortex-M0 */ |
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| 142 | |||
| 143 | /* Initialize blkCnt with number of samples */ |
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| 144 | blkCnt = blockSize; |
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| 145 | |||
| 146 | while(blkCnt > 0u) |
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| 147 | { |
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| 148 | /* C = A * scale */ |
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| 149 | /* Scale the input and then store the result in the destination buffer. */ |
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| 150 | *pDst++ = (q15_t) (__SSAT(((q31_t) * pSrc++ * scaleFract) >> kShift, 16)); |
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| 151 | |||
| 152 | /* Decrement the loop counter */ |
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| 153 | blkCnt--; |
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| 154 | } |
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| 155 | |||
| 156 | #endif /* #ifndef ARM_MATH_CM0_FAMILY */ |
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| 157 | |||
| 158 | } |
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| 159 | |||
| 160 | /** |
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| 161 | * @} end of scale group |
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| 162 | */ |