1 /* ----------------------------------------------------------------------
2 * Project: CMSIS DSP Library
3 * Title: arm_scale_q7.c
4 * Description: Multiplies a Q7 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 Q7 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 1.7 format.
51 These are multiplied to yield a 2.14 intermediate result and this is shifted with saturation to 1.7 format.
52 */
53
54 #if defined(ARM_MATH_MVEI) && !defined(ARM_MATH_AUTOVECTORIZE)
55
56 #include "arm_helium_utils.h"
57
58
arm_scale_q7(const q7_t * pSrc,q7_t scaleFract,int8_t shift,q7_t * pDst,uint32_t blockSize)59 void arm_scale_q7(
60 const q7_t * pSrc,
61 q7_t scaleFract,
62 int8_t shift,
63 q7_t * pDst,
64 uint32_t blockSize)
65 {
66 uint32_t blkCnt; /* loop counters */
67 q7x16_t vecSrc;
68 q7x16_t vecDst;
69
70
71 /* Compute 16 outputs at a time */
72 blkCnt = blockSize >> 4;
73
74 while (blkCnt > 0U)
75 {
76 /*
77 * C = A * scale
78 * Scale the input and then store the result in the destination buffer.
79 */
80 vecSrc = vld1q(pSrc);
81 vecDst = vmulhq(vecSrc, vdupq_n_s8(scaleFract));
82 vecDst = vqshlq_r(vecDst, shift + 1);
83 vst1q(pDst, vecDst);
84 /*
85 * Decrement the blockSize loop counter
86 */
87 blkCnt--;
88 /*
89 * advance vector source and destination pointers
90 */
91 pSrc += 16;
92 pDst += 16;
93 }
94 /*
95 * tail
96 */
97 blkCnt = blockSize & 0xF;
98 if (blkCnt > 0U)
99 {
100 mve_pred16_t p0 = vctp8q(blkCnt);
101 vecSrc = vld1q(pSrc);
102 vecDst = vmulhq(vecSrc, vdupq_n_s8(scaleFract));
103 vecDst = vqshlq_r(vecDst, shift + 1);
104 vstrbq_p(pDst, vecDst, p0);
105 }
106
107 }
108
109 #else
arm_scale_q7(const q7_t * pSrc,q7_t scaleFract,int8_t shift,q7_t * pDst,uint32_t blockSize)110 void arm_scale_q7(
111 const q7_t * pSrc,
112 q7_t scaleFract,
113 int8_t shift,
114 q7_t * pDst,
115 uint32_t blockSize)
116 {
117 uint32_t blkCnt; /* Loop counter */
118 int8_t kShift = 7 - shift; /* Shift to apply after scaling */
119
120 #if defined (ARM_MATH_LOOPUNROLL)
121
122 #if defined (ARM_MATH_DSP)
123 q7_t in1, in2, in3, in4; /* Temporary input variables */
124 q7_t out1, out2, out3, out4; /* Temporary output variables */
125 #endif
126
127 /* Loop unrolling: Compute 4 outputs at a time */
128 blkCnt = blockSize >> 2U;
129
130 while (blkCnt > 0U)
131 {
132 /* C = A * scale */
133
134 #if defined (ARM_MATH_DSP)
135 /* Reading 4 inputs from memory */
136 in1 = *pSrc++;
137 in2 = *pSrc++;
138 in3 = *pSrc++;
139 in4 = *pSrc++;
140
141 /* Scale inputs and store result in the temporary variable. */
142 out1 = (q7_t) (__SSAT(((in1) * scaleFract) >> kShift, 8));
143 out2 = (q7_t) (__SSAT(((in2) * scaleFract) >> kShift, 8));
144 out3 = (q7_t) (__SSAT(((in3) * scaleFract) >> kShift, 8));
145 out4 = (q7_t) (__SSAT(((in4) * scaleFract) >> kShift, 8));
146
147 /* Pack and store result in destination buffer (in single write) */
148 write_q7x4_ia (&pDst, __PACKq7(out1, out2, out3, out4));
149 #else
150 *pDst++ = (q7_t) (__SSAT((((q15_t) *pSrc++ * scaleFract) >> kShift), 8));
151 *pDst++ = (q7_t) (__SSAT((((q15_t) *pSrc++ * scaleFract) >> kShift), 8));
152 *pDst++ = (q7_t) (__SSAT((((q15_t) *pSrc++ * scaleFract) >> kShift), 8));
153 *pDst++ = (q7_t) (__SSAT((((q15_t) *pSrc++ * scaleFract) >> kShift), 8));
154 #endif
155
156 /* Decrement loop counter */
157 blkCnt--;
158 }
159
160 /* Loop unrolling: Compute remaining outputs */
161 blkCnt = blockSize % 0x4U;
162
163 #else
164
165 /* Initialize blkCnt with number of samples */
166 blkCnt = blockSize;
167
168 #endif /* #if defined (ARM_MATH_LOOPUNROLL) */
169
170 while (blkCnt > 0U)
171 {
172 /* C = A * scale */
173
174 /* Scale input and store result in destination buffer. */
175 *pDst++ = (q7_t) (__SSAT((((q15_t) *pSrc++ * scaleFract) >> kShift), 8));
176
177 /* Decrement loop counter */
178 blkCnt--;
179 }
180
181 }
182 #endif /* defined(ARM_MATH_MVEI) */
183
184 /**
185 @} end of BasicScale group
186 */
187
