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The CMSIS DSP 5 library

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functions/BasicMathFunctions/arm_scale_q7.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

Who changed what in which revision?

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xorjoep 1:24714b45cd1b 1 /* ----------------------------------------------------------------------
xorjoep 1:24714b45cd1b 2 * Project: CMSIS DSP Library
xorjoep 1:24714b45cd1b 3 * Title: arm_scale_q7.c
xorjoep 1:24714b45cd1b 4 * Description: Multiplies a Q7 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 Q7 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 1.7 format.
xorjoep 1:24714b45cd1b 52 * These are multiplied to yield a 2.14 intermediate result and this is shifted with saturation to 1.7 format.
xorjoep 1:24714b45cd1b 53 */
xorjoep 1:24714b45cd1b 54
xorjoep 1:24714b45cd1b 55 void arm_scale_q7(
xorjoep 1:24714b45cd1b 56 q7_t * pSrc,
xorjoep 1:24714b45cd1b 57 q7_t scaleFract,
xorjoep 1:24714b45cd1b 58 int8_t shift,
xorjoep 1:24714b45cd1b 59 q7_t * pDst,
xorjoep 1:24714b45cd1b 60 uint32_t blockSize)
xorjoep 1:24714b45cd1b 61 {
xorjoep 1:24714b45cd1b 62 int8_t kShift = 7 - shift; /* shift to apply after scaling */
xorjoep 1:24714b45cd1b 63 uint32_t blkCnt; /* loop counter */
xorjoep 1:24714b45cd1b 64
xorjoep 1:24714b45cd1b 65 #if defined (ARM_MATH_DSP)
xorjoep 1:24714b45cd1b 66
xorjoep 1:24714b45cd1b 67 /* Run the below code for Cortex-M4 and Cortex-M3 */
xorjoep 1:24714b45cd1b 68 q7_t in1, in2, in3, in4, out1, out2, out3, out4; /* Temporary variables to store input & output */
xorjoep 1:24714b45cd1b 69
xorjoep 1:24714b45cd1b 70
xorjoep 1:24714b45cd1b 71 /*loop Unrolling */
xorjoep 1:24714b45cd1b 72 blkCnt = blockSize >> 2U;
xorjoep 1:24714b45cd1b 73
xorjoep 1:24714b45cd1b 74
xorjoep 1:24714b45cd1b 75 /* First part of the processing with loop unrolling. Compute 4 outputs at a time.
xorjoep 1:24714b45cd1b 76 ** a second loop below computes the remaining 1 to 3 samples. */
xorjoep 1:24714b45cd1b 77 while (blkCnt > 0U)
xorjoep 1:24714b45cd1b 78 {
xorjoep 1:24714b45cd1b 79 /* Reading 4 inputs from memory */
xorjoep 1:24714b45cd1b 80 in1 = *pSrc++;
xorjoep 1:24714b45cd1b 81 in2 = *pSrc++;
xorjoep 1:24714b45cd1b 82 in3 = *pSrc++;
xorjoep 1:24714b45cd1b 83 in4 = *pSrc++;
xorjoep 1:24714b45cd1b 84
xorjoep 1:24714b45cd1b 85 /* C = A * scale */
xorjoep 1:24714b45cd1b 86 /* Scale the inputs and then store the results in the temporary variables. */
xorjoep 1:24714b45cd1b 87 out1 = (q7_t) (__SSAT(((in1) * scaleFract) >> kShift, 8));
xorjoep 1:24714b45cd1b 88 out2 = (q7_t) (__SSAT(((in2) * scaleFract) >> kShift, 8));
xorjoep 1:24714b45cd1b 89 out3 = (q7_t) (__SSAT(((in3) * scaleFract) >> kShift, 8));
xorjoep 1:24714b45cd1b 90 out4 = (q7_t) (__SSAT(((in4) * scaleFract) >> kShift, 8));
xorjoep 1:24714b45cd1b 91
xorjoep 1:24714b45cd1b 92 /* Packing the individual outputs into 32bit and storing in
xorjoep 1:24714b45cd1b 93 * destination buffer in single write */
xorjoep 1:24714b45cd1b 94 *__SIMD32(pDst)++ = __PACKq7(out1, out2, out3, out4);
xorjoep 1:24714b45cd1b 95
xorjoep 1:24714b45cd1b 96 /* Decrement the loop counter */
xorjoep 1:24714b45cd1b 97 blkCnt--;
xorjoep 1:24714b45cd1b 98 }
xorjoep 1:24714b45cd1b 99
xorjoep 1:24714b45cd1b 100 /* If the blockSize is not a multiple of 4, compute any remaining output samples here.
xorjoep 1:24714b45cd1b 101 ** No loop unrolling is used. */
xorjoep 1:24714b45cd1b 102 blkCnt = blockSize % 0x4U;
xorjoep 1:24714b45cd1b 103
xorjoep 1:24714b45cd1b 104 while (blkCnt > 0U)
xorjoep 1:24714b45cd1b 105 {
xorjoep 1:24714b45cd1b 106 /* C = A * scale */
xorjoep 1:24714b45cd1b 107 /* Scale the input and then store the result in the destination buffer. */
xorjoep 1:24714b45cd1b 108 *pDst++ = (q7_t) (__SSAT(((*pSrc++) * scaleFract) >> kShift, 8));
xorjoep 1:24714b45cd1b 109
xorjoep 1:24714b45cd1b 110 /* Decrement the loop counter */
xorjoep 1:24714b45cd1b 111 blkCnt--;
xorjoep 1:24714b45cd1b 112 }
xorjoep 1:24714b45cd1b 113
xorjoep 1:24714b45cd1b 114 #else
xorjoep 1:24714b45cd1b 115
xorjoep 1:24714b45cd1b 116 /* Run the below code for Cortex-M0 */
xorjoep 1:24714b45cd1b 117
xorjoep 1:24714b45cd1b 118 /* Initialize blkCnt with number of samples */
xorjoep 1:24714b45cd1b 119 blkCnt = blockSize;
xorjoep 1:24714b45cd1b 120
xorjoep 1:24714b45cd1b 121 while (blkCnt > 0U)
xorjoep 1:24714b45cd1b 122 {
xorjoep 1:24714b45cd1b 123 /* C = A * scale */
xorjoep 1:24714b45cd1b 124 /* Scale the input and then store the result in the destination buffer. */
xorjoep 1:24714b45cd1b 125 *pDst++ = (q7_t) (__SSAT((((q15_t) * pSrc++ * scaleFract) >> kShift), 8));
xorjoep 1:24714b45cd1b 126
xorjoep 1:24714b45cd1b 127 /* Decrement the loop counter */
xorjoep 1:24714b45cd1b 128 blkCnt--;
xorjoep 1:24714b45cd1b 129 }
xorjoep 1:24714b45cd1b 130
xorjoep 1:24714b45cd1b 131 #endif /* #if defined (ARM_MATH_DSP) */
xorjoep 1:24714b45cd1b 132
xorjoep 1:24714b45cd1b 133 }
xorjoep 1:24714b45cd1b 134
xorjoep 1:24714b45cd1b 135 /**
xorjoep 1:24714b45cd1b 136 * @} end of scale group
xorjoep 1:24714b45cd1b 137 */