source: S-port/trunk/Drivers/CMSIS/DSP/Source/BasicMathFunctions/arm_scale_q15.c

Last change on this file was 1, checked in by AlexLir, 3 years ago
File size: 4.4 KB
Line 
1/* ----------------------------------------------------------------------
2 * Project: CMSIS DSP Library
3 * Title: arm_scale_q15.c
4 * Description: Multiplies a Q15 vector by a scalar
5 *
6 * $Date: 27. January 2017
7 * $Revision: V.1.5.1
8 *
9 * Target Processor: Cortex-M cores
10 * -------------------------------------------------------------------- */
11/*
12 * Copyright (C) 2010-2017 ARM Limited or its affiliates. All rights reserved.
13 *
14 * SPDX-License-Identifier: Apache-2.0
15 *
16 * Licensed under the Apache License, Version 2.0 (the License); you may
17 * not use this file except in compliance with the License.
18 * You may obtain a copy of the License at
19 *
20 * www.apache.org/licenses/LICENSE-2.0
21 *
22 * Unless required by applicable law or agreed to in writing, software
23 * distributed under the License is distributed on an AS IS BASIS, WITHOUT
24 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
25 * See the License for the specific language governing permissions and
26 * limitations under the License.
27 */
28
29#include "arm_math.h"
30
31/**
32 * @ingroup groupMath
33 */
34
35/**
36 * @addtogroup scale
37 * @{
38 */
39
40/**
41 * @brief Multiplies a Q15 vector by a scalar.
42 * @param[in] *pSrc points to the input vector
43 * @param[in] scaleFract fractional portion of the scale value
44 * @param[in] shift number of bits to shift the result by
45 * @param[out] *pDst points to the output vector
46 * @param[in] blockSize number of samples in the vector
47 * @return none.
48 *
49 * <b>Scaling and Overflow Behavior:</b>
50 * \par
51 * The input data <code>*pSrc</code> and <code>scaleFract</code> are in 1.15 format.
52 * These are multiplied to yield a 2.30 intermediate result and this is shifted with saturation to 1.15 format.
53 */
54
55
56void arm_scale_q15(
57 q15_t * pSrc,
58 q15_t scaleFract,
59 int8_t shift,
60 q15_t * pDst,
61 uint32_t blockSize)
62{
63 int8_t kShift = 15 - shift; /* shift to apply after scaling */
64 uint32_t blkCnt; /* loop counter */
65
66#if defined (ARM_MATH_DSP)
67
68/* Run the below code for Cortex-M4 and Cortex-M3 */
69 q15_t in1, in2, in3, in4;
70 q31_t inA1, inA2; /* Temporary variables */
71 q31_t out1, out2, out3, out4;
72
73
74 /*loop Unrolling */
75 blkCnt = blockSize >> 2U;
76
77 /* First part of the processing with loop unrolling. Compute 4 outputs at a time.
78 ** a second loop below computes the remaining 1 to 3 samples. */
79 while (blkCnt > 0U)
80 {
81 /* Reading 2 inputs from memory */
82 inA1 = *__SIMD32(pSrc)++;
83 inA2 = *__SIMD32(pSrc)++;
84
85 /* C = A * scale */
86 /* Scale the inputs and then store the 2 results in the destination buffer
87 * in single cycle by packing the outputs */
88 out1 = (q31_t) ((q15_t) (inA1 >> 16) * scaleFract);
89 out2 = (q31_t) ((q15_t) inA1 * scaleFract);
90 out3 = (q31_t) ((q15_t) (inA2 >> 16) * scaleFract);
91 out4 = (q31_t) ((q15_t) inA2 * scaleFract);
92
93 /* apply shifting */
94 out1 = out1 >> kShift;
95 out2 = out2 >> kShift;
96 out3 = out3 >> kShift;
97 out4 = out4 >> kShift;
98
99 /* saturate the output */
100 in1 = (q15_t) (__SSAT(out1, 16));
101 in2 = (q15_t) (__SSAT(out2, 16));
102 in3 = (q15_t) (__SSAT(out3, 16));
103 in4 = (q15_t) (__SSAT(out4, 16));
104
105 /* store the result to destination */
106 *__SIMD32(pDst)++ = __PKHBT(in2, in1, 16);
107 *__SIMD32(pDst)++ = __PKHBT(in4, in3, 16);
108
109 /* Decrement the loop counter */
110 blkCnt--;
111 }
112
113 /* If the blockSize is not a multiple of 4, compute any remaining output samples here.
114 ** No loop unrolling is used. */
115 blkCnt = blockSize % 0x4U;
116
117 while (blkCnt > 0U)
118 {
119 /* C = A * scale */
120 /* Scale the input and then store the result in the destination buffer. */
121 *pDst++ = (q15_t) (__SSAT(((*pSrc++) * scaleFract) >> kShift, 16));
122
123 /* Decrement the loop counter */
124 blkCnt--;
125 }
126
127#else
128
129 /* Run the below code for Cortex-M0 */
130
131 /* Initialize blkCnt with number of samples */
132 blkCnt = blockSize;
133
134 while (blkCnt > 0U)
135 {
136 /* C = A * scale */
137 /* Scale the input and then store the result in the destination buffer. */
138 *pDst++ = (q15_t) (__SSAT(((q31_t) * pSrc++ * scaleFract) >> kShift, 16));
139
140 /* Decrement the loop counter */
141 blkCnt--;
142 }
143
144#endif /* #if defined (ARM_MATH_DSP) */
145
146}
147
148/**
149 * @} end of scale group
150 */
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