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The CMSIS DSP 5 library

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functions/BasicMathFunctions/arm_scale_q15.c@3:4098b9d3d571, 2018-06-21 (annotated)

Committer:
xorjoep
Date:
Thu Jun 21 11:56:27 2018 +0000
Revision:
3:4098b9d3d571
Parent:
1:24714b45cd1b 
headers is a folder not a library

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xorjoep 1:24714b45cd1b 1 /* ----------------------------------------------------------------------
xorjoep 1:24714b45cd1b 2 * Project: CMSIS DSP Library
xorjoep 1:24714b45cd1b 3 * Title: arm_scale_q15.c
xorjoep 1:24714b45cd1b 4 * Description: Multiplies a Q15 vector by a scalar
xorjoep 1:24714b45cd1b 5 *
xorjoep 1:24714b45cd1b 6 * $Date: 27. January 2017
xorjoep 1:24714b45cd1b 7 * $Revision: V.1.5.1
xorjoep 1:24714b45cd1b 8 *
xorjoep 1:24714b45cd1b 9 * Target Processor: Cortex-M cores
xorjoep 1:24714b45cd1b 10 * -------------------------------------------------------------------- */
xorjoep 1:24714b45cd1b 11 /*
xorjoep 1:24714b45cd1b 12 * Copyright (C) 2010-2017 ARM Limited or its affiliates. All rights reserved.
xorjoep 1:24714b45cd1b 13 *
xorjoep 1:24714b45cd1b 14 * SPDX-License-Identifier: Apache-2.0
xorjoep 1:24714b45cd1b 15 *
xorjoep 1:24714b45cd1b 16 * Licensed under the Apache License, Version 2.0 (the License); you may
xorjoep 1:24714b45cd1b 17 * not use this file except in compliance with the License.
xorjoep 1:24714b45cd1b 18 * You may obtain a copy of the License at
xorjoep 1:24714b45cd1b 19 *
xorjoep 1:24714b45cd1b 20 * www.apache.org/licenses/LICENSE-2.0
xorjoep 1:24714b45cd1b 21 *
xorjoep 1:24714b45cd1b 22 * Unless required by applicable law or agreed to in writing, software
xorjoep 1:24714b45cd1b 23 * distributed under the License is distributed on an AS IS BASIS, WITHOUT
xorjoep 1:24714b45cd1b 24 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
xorjoep 1:24714b45cd1b 25 * See the License for the specific language governing permissions and
xorjoep 1:24714b45cd1b 26 * limitations under the License.
xorjoep 1:24714b45cd1b 27 */
xorjoep 1:24714b45cd1b 28
xorjoep 1:24714b45cd1b 29 #include "arm_math.h"
xorjoep 1:24714b45cd1b 30
xorjoep 1:24714b45cd1b 31 /**
xorjoep 1:24714b45cd1b 32 * @ingroup groupMath
xorjoep 1:24714b45cd1b 33 */
xorjoep 1:24714b45cd1b 34
xorjoep 1:24714b45cd1b 35 /**
xorjoep 1:24714b45cd1b 36 * @addtogroup scale
xorjoep 1:24714b45cd1b 37 * @{
xorjoep 1:24714b45cd1b 38 */
xorjoep 1:24714b45cd1b 39
xorjoep 1:24714b45cd1b 40 /**
xorjoep 1:24714b45cd1b 41 * @brief Multiplies a Q15 vector by a scalar.
xorjoep 1:24714b45cd1b 42 * @param[in] *pSrc points to the input vector
xorjoep 1:24714b45cd1b 43 * @param[in] scaleFract fractional portion of the scale value
xorjoep 1:24714b45cd1b 44 * @param[in] shift number of bits to shift the result by
xorjoep 1:24714b45cd1b 45 * @param[out] *pDst points to the output vector
xorjoep 1:24714b45cd1b 46 * @param[in] blockSize number of samples in the vector
xorjoep 1:24714b45cd1b 47 * @return none.
xorjoep 1:24714b45cd1b 48 *
xorjoep 1:24714b45cd1b 49 * <b>Scaling and Overflow Behavior:</b>
xorjoep 1:24714b45cd1b 50 * \par
xorjoep 1:24714b45cd1b 51 * The input data <code>*pSrc</code> and <code>scaleFract</code> are in 1.15 format.
xorjoep 1:24714b45cd1b 52 * These are multiplied to yield a 2.30 intermediate result and this is shifted with saturation to 1.15 format.
xorjoep 1:24714b45cd1b 53 */
xorjoep 1:24714b45cd1b 54
xorjoep 1:24714b45cd1b 55
xorjoep 1:24714b45cd1b 56 void arm_scale_q15(
xorjoep 1:24714b45cd1b 57 q15_t * pSrc,
xorjoep 1:24714b45cd1b 58 q15_t scaleFract,
xorjoep 1:24714b45cd1b 59 int8_t shift,
xorjoep 1:24714b45cd1b 60 q15_t * pDst,
xorjoep 1:24714b45cd1b 61 uint32_t blockSize)
xorjoep 1:24714b45cd1b 62 {
xorjoep 1:24714b45cd1b 63 int8_t kShift = 15 - shift; /* shift to apply after scaling */
xorjoep 1:24714b45cd1b 64 uint32_t blkCnt; /* loop counter */
xorjoep 1:24714b45cd1b 65
xorjoep 1:24714b45cd1b 66 #if defined (ARM_MATH_DSP)
xorjoep 1:24714b45cd1b 67
xorjoep 1:24714b45cd1b 68 /* Run the below code for Cortex-M4 and Cortex-M3 */
xorjoep 1:24714b45cd1b 69 q15_t in1, in2, in3, in4;
xorjoep 1:24714b45cd1b 70 q31_t inA1, inA2; /* Temporary variables */
xorjoep 1:24714b45cd1b 71 q31_t out1, out2, out3, out4;
xorjoep 1:24714b45cd1b 72
xorjoep 1:24714b45cd1b 73
xorjoep 1:24714b45cd1b 74 /*loop Unrolling */
xorjoep 1:24714b45cd1b 75 blkCnt = blockSize >> 2U;
xorjoep 1:24714b45cd1b 76
xorjoep 1:24714b45cd1b 77 /* First part of the processing with loop unrolling. Compute 4 outputs at a time.
xorjoep 1:24714b45cd1b 78 ** a second loop below computes the remaining 1 to 3 samples. */
xorjoep 1:24714b45cd1b 79 while (blkCnt > 0U)
xorjoep 1:24714b45cd1b 80 {
xorjoep 1:24714b45cd1b 81 /* Reading 2 inputs from memory */
xorjoep 1:24714b45cd1b 82 inA1 = *__SIMD32(pSrc)++;
xorjoep 1:24714b45cd1b 83 inA2 = *__SIMD32(pSrc)++;
xorjoep 1:24714b45cd1b 84
xorjoep 1:24714b45cd1b 85 /* C = A * scale */
xorjoep 1:24714b45cd1b 86 /* Scale the inputs and then store the 2 results in the destination buffer
xorjoep 1:24714b45cd1b 87 * in single cycle by packing the outputs */
xorjoep 1:24714b45cd1b 88 out1 = (q31_t) ((q15_t) (inA1 >> 16) * scaleFract);
xorjoep 1:24714b45cd1b 89 out2 = (q31_t) ((q15_t) inA1 * scaleFract);
xorjoep 1:24714b45cd1b 90 out3 = (q31_t) ((q15_t) (inA2 >> 16) * scaleFract);
xorjoep 1:24714b45cd1b 91 out4 = (q31_t) ((q15_t) inA2 * scaleFract);
xorjoep 1:24714b45cd1b 92
xorjoep 1:24714b45cd1b 93 /* apply shifting */
xorjoep 1:24714b45cd1b 94 out1 = out1 >> kShift;
xorjoep 1:24714b45cd1b 95 out2 = out2 >> kShift;
xorjoep 1:24714b45cd1b 96 out3 = out3 >> kShift;
xorjoep 1:24714b45cd1b 97 out4 = out4 >> kShift;
xorjoep 1:24714b45cd1b 98
xorjoep 1:24714b45cd1b 99 /* saturate the output */
xorjoep 1:24714b45cd1b 100 in1 = (q15_t) (__SSAT(out1, 16));
xorjoep 1:24714b45cd1b 101 in2 = (q15_t) (__SSAT(out2, 16));
xorjoep 1:24714b45cd1b 102 in3 = (q15_t) (__SSAT(out3, 16));
xorjoep 1:24714b45cd1b 103 in4 = (q15_t) (__SSAT(out4, 16));
xorjoep 1:24714b45cd1b 104
xorjoep 1:24714b45cd1b 105 /* store the result to destination */
xorjoep 1:24714b45cd1b 106 *__SIMD32(pDst)++ = __PKHBT(in2, in1, 16);
xorjoep 1:24714b45cd1b 107 *__SIMD32(pDst)++ = __PKHBT(in4, in3, 16);
xorjoep 1:24714b45cd1b 108
xorjoep 1:24714b45cd1b 109 /* Decrement the loop counter */
xorjoep 1:24714b45cd1b 110 blkCnt--;
xorjoep 1:24714b45cd1b 111 }
xorjoep 1:24714b45cd1b 112
xorjoep 1:24714b45cd1b 113 /* If the blockSize is not a multiple of 4, compute any remaining output samples here.
xorjoep 1:24714b45cd1b 114 ** No loop unrolling is used. */
xorjoep 1:24714b45cd1b 115 blkCnt = blockSize % 0x4U;
xorjoep 1:24714b45cd1b 116
xorjoep 1:24714b45cd1b 117 while (blkCnt > 0U)
xorjoep 1:24714b45cd1b 118 {
xorjoep 1:24714b45cd1b 119 /* C = A * scale */
xorjoep 1:24714b45cd1b 120 /* Scale the input and then store the result in the destination buffer. */
xorjoep 1:24714b45cd1b 121 *pDst++ = (q15_t) (__SSAT(((*pSrc++) * scaleFract) >> kShift, 16));
xorjoep 1:24714b45cd1b 122
xorjoep 1:24714b45cd1b 123 /* Decrement the loop counter */
xorjoep 1:24714b45cd1b 124 blkCnt--;
xorjoep 1:24714b45cd1b 125 }
xorjoep 1:24714b45cd1b 126
xorjoep 1:24714b45cd1b 127 #else
xorjoep 1:24714b45cd1b 128
xorjoep 1:24714b45cd1b 129 /* Run the below code for Cortex-M0 */
xorjoep 1:24714b45cd1b 130
xorjoep 1:24714b45cd1b 131 /* Initialize blkCnt with number of samples */
xorjoep 1:24714b45cd1b 132 blkCnt = blockSize;
xorjoep 1:24714b45cd1b 133
xorjoep 1:24714b45cd1b 134 while (blkCnt > 0U)
xorjoep 1:24714b45cd1b 135 {
xorjoep 1:24714b45cd1b 136 /* C = A * scale */
xorjoep 1:24714b45cd1b 137 /* Scale the input and then store the result in the destination buffer. */
xorjoep 1:24714b45cd1b 138 *pDst++ = (q15_t) (__SSAT(((q31_t) * pSrc++ * scaleFract) >> kShift, 16));
xorjoep 1:24714b45cd1b 139
xorjoep 1:24714b45cd1b 140 /* Decrement the loop counter */
xorjoep 1:24714b45cd1b 141 blkCnt--;
xorjoep 1:24714b45cd1b 142 }
xorjoep 1:24714b45cd1b 143
xorjoep 1:24714b45cd1b 144 #endif /* #if defined (ARM_MATH_DSP) */
xorjoep 1:24714b45cd1b 145
xorjoep 1:24714b45cd1b 146 }
xorjoep 1:24714b45cd1b 147
xorjoep 1:24714b45cd1b 148 /**
xorjoep 1:24714b45cd1b 149 * @} end of scale group
xorjoep 1:24714b45cd1b 150 */