1 /* ----------------------------------------------------------------------
2 * Project: CMSIS DSP Library
3 * Title: arm_scale_q15.c
4 * Description: Multiplies a Q15 vector by a scalar
5 *
6 * $Date: 23 April 2021
7 * $Revision: V1.9.0
8 *
9 * Target Processor: Cortex-M and Cortex-A cores
10 * -------------------------------------------------------------------- */
11 /*
12 * Copyright (C) 2010-2021 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 "dsp/basic_math_functions.h"
30
31 /**
32 @ingroup groupMath
33 */
34
35 /**
36 @addtogroup BasicScale
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 each vector
47 @return none
48
49 @par Scaling and Overflow Behavior
50 The input data <code>*pSrc</code> and <code>scaleFract</code> are in 1.15 format.
51 These are multiplied to yield a 2.30 intermediate result and this is shifted with saturation to 1.15 format.
52 */
53
54 #if defined(ARM_MATH_MVEI) && !defined(ARM_MATH_AUTOVECTORIZE)
55
56 #include "arm_helium_utils.h"
57
arm_scale_q15(const q15_t * pSrc,q15_t scaleFract,int8_t shift,q15_t * pDst,uint32_t blockSize)58 void arm_scale_q15(
59 const q15_t * pSrc,
60 q15_t scaleFract,
61 int8_t shift,
62 q15_t * pDst,
63 uint32_t blockSize)
64 {
65 uint32_t blkCnt; /* loop counters */
66 q15x8_t vecSrc;
67 q15x8_t vecDst;
68
69
70 /* Compute 8 outputs at a time */
71 blkCnt = blockSize >> 3;
72
73 while (blkCnt > 0U)
74 {
75 /*
76 * C = A * scale
77 * Scale the input and then store the result in the destination buffer.
78 */
79 vecSrc = vld1q(pSrc);
80 vecDst = vmulhq(vecSrc, vdupq_n_s16(scaleFract));
81 vecDst = vqshlq_r(vecDst, shift + 1);
82 vst1q(pDst, vecDst);
83 /*
84 * Decrement the blockSize loop counter
85 */
86 blkCnt--;
87 /*
88 * advance vector source and destination pointers
89 */
90 pSrc += 8;
91 pDst += 8;
92 }
93 /*
94 * tail
95 */
96 blkCnt = blockSize & 7;
97 if (blkCnt > 0U)
98 {
99 mve_pred16_t p0 = vctp16q(blkCnt);;
100 vecSrc = vld1q(pSrc);
101 vecDst = vmulhq(vecSrc, vdupq_n_s16(scaleFract));
102 vecDst = vqshlq_r(vecDst, shift + 1);
103 vstrhq_p(pDst, vecDst, p0);
104 }
105
106 }
107
108
109 #else
arm_scale_q15(const q15_t * pSrc,q15_t scaleFract,int8_t shift,q15_t * pDst,uint32_t blockSize)110 void arm_scale_q15(
111 const q15_t *pSrc,
112 q15_t scaleFract,
113 int8_t shift,
114 q15_t *pDst,
115 uint32_t blockSize)
116 {
117 uint32_t blkCnt; /* Loop counter */
118 int8_t kShift = 15 - shift; /* Shift to apply after scaling */
119
120 #if defined (ARM_MATH_LOOPUNROLL)
121 #if defined (ARM_MATH_DSP)
122 q31_t inA1, inA2;
123 q31_t out1, out2, out3, out4; /* Temporary output variables */
124 q15_t in1, in2, in3, in4; /* Temporary input variables */
125 #endif
126 #endif
127
128 #if defined (ARM_MATH_LOOPUNROLL)
129
130 /* Loop unrolling: Compute 4 outputs at a time */
131 blkCnt = blockSize >> 2U;
132
133 while (blkCnt > 0U)
134 {
135 /* C = A * scale */
136
137 #if defined (ARM_MATH_DSP)
138 /* read 2 times 2 samples at a time from source */
139 inA1 = read_q15x2_ia ((q15_t **) &pSrc);
140 inA2 = read_q15x2_ia ((q15_t **) &pSrc);
141
142 /* Scale inputs and store result in temporary variables
143 * in single cycle by packing the outputs */
144 out1 = (q31_t) ((q15_t) (inA1 >> 16) * scaleFract);
145 out2 = (q31_t) ((q15_t) (inA1 ) * scaleFract);
146 out3 = (q31_t) ((q15_t) (inA2 >> 16) * scaleFract);
147 out4 = (q31_t) ((q15_t) (inA2 ) * scaleFract);
148
149 /* apply shifting */
150 out1 = out1 >> kShift;
151 out2 = out2 >> kShift;
152 out3 = out3 >> kShift;
153 out4 = out4 >> kShift;
154
155 /* saturate the output */
156 in1 = (q15_t) (__SSAT(out1, 16));
157 in2 = (q15_t) (__SSAT(out2, 16));
158 in3 = (q15_t) (__SSAT(out3, 16));
159 in4 = (q15_t) (__SSAT(out4, 16));
160
161 /* store result to destination */
162 write_q15x2_ia (&pDst, __PKHBT(in2, in1, 16));
163 write_q15x2_ia (&pDst, __PKHBT(in4, in3, 16));
164 #else
165 *pDst++ = (q15_t) (__SSAT(((q31_t) *pSrc++ * scaleFract) >> kShift, 16));
166 *pDst++ = (q15_t) (__SSAT(((q31_t) *pSrc++ * scaleFract) >> kShift, 16));
167 *pDst++ = (q15_t) (__SSAT(((q31_t) *pSrc++ * scaleFract) >> kShift, 16));
168 *pDst++ = (q15_t) (__SSAT(((q31_t) *pSrc++ * scaleFract) >> kShift, 16));
169 #endif
170
171 /* Decrement loop counter */
172 blkCnt--;
173 }
174
175 /* Loop unrolling: Compute remaining outputs */
176 blkCnt = blockSize % 0x4U;
177
178 #else
179
180 /* Initialize blkCnt with number of samples */
181 blkCnt = blockSize;
182
183 #endif /* #if defined (ARM_MATH_LOOPUNROLL) */
184
185 while (blkCnt > 0U)
186 {
187 /* C = A * scale */
188
189 /* Scale input and store result in destination buffer. */
190 *pDst++ = (q15_t) (__SSAT(((q31_t) *pSrc++ * scaleFract) >> kShift, 16));
191
192 /* Decrement loop counter */
193 blkCnt--;
194 }
195
196 }
197 #endif /* defined(ARM_MATH_MVEI) */
198
199 /**
200 @} end of BasicScale group
201 */
202
