1 /* ----------------------------------------------------------------------
2 * Project: CMSIS DSP Library
3 * Title: arm_shift_q7.c
4 * Description: Processing function for the Q7 Shifting
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 BasicShift
37 @{
38 */
39
40 /**
41 @brief Shifts the elements of a Q7 vector a specified number of bits
42 @param[in] pSrc points to the input vector
43 @param[in] shiftBits number of bits to shift. A positive value shifts left; a negative value shifts right.
44 @param[out] pDst points to the output vector
45 @param[in] blockSize number of samples in each vector
46 @return none
47
48 @par onditions for optimum performance
49 Input and output buffers should be aligned by 32-bit
50 @par Scaling and Overflow Behavior
51 The function uses saturating arithmetic.
52 Results outside of the allowable Q7 range [0x80 0x7F] are saturated.
53 */
54
55 #if defined(ARM_MATH_MVEI) && !defined(ARM_MATH_AUTOVECTORIZE)
56
57 #include "arm_helium_utils.h"
58
arm_shift_q7(const q7_t * pSrc,int8_t shiftBits,q7_t * pDst,uint32_t blockSize)59 void arm_shift_q7(
60 const q7_t * pSrc,
61 int8_t shiftBits,
62 q7_t * pDst,
63 uint32_t blockSize)
64 {
65 uint32_t blkCnt; /* loop counters */
66 q7x16_t vecSrc;
67 q7x16_t vecDst;
68
69 /* Compute 16 outputs at a time */
70 blkCnt = blockSize >> 4;
71 while (blkCnt > 0U)
72 {
73 /*
74 * C = A (>> or <<) shiftBits
75 * Shift the input and then store the result in the destination buffer.
76 */
77 vecSrc = vld1q(pSrc);
78 vecDst = vqshlq_r(vecSrc, shiftBits);
79 vst1q(pDst, vecDst);
80 /*
81 * Decrement the blockSize loop counter
82 */
83 blkCnt--;
84 /*
85 * advance vector source and destination pointers
86 */
87 pSrc += 16;
88 pDst += 16;
89 }
90 /*
91 * tail
92 */
93 blkCnt = blockSize & 0xF;
94 if (blkCnt > 0U)
95 {
96 mve_pred16_t p0 = vctp8q(blkCnt);
97 vecSrc = vld1q(pSrc);
98 vecDst = vqshlq_r(vecSrc, shiftBits);
99 vstrbq_p(pDst, vecDst, p0);
100 }
101 }
102
103 #else
arm_shift_q7(const q7_t * pSrc,int8_t shiftBits,q7_t * pDst,uint32_t blockSize)104 void arm_shift_q7(
105 const q7_t * pSrc,
106 int8_t shiftBits,
107 q7_t * pDst,
108 uint32_t blockSize)
109 {
110 uint32_t blkCnt; /* Loop counter */
111 uint8_t sign = (shiftBits & 0x80); /* Sign of shiftBits */
112
113 #if defined (ARM_MATH_LOOPUNROLL)
114
115 #if defined (ARM_MATH_DSP)
116 q7_t in1, in2, in3, in4; /* Temporary input variables */
117 #endif
118
119 /* Loop unrolling: Compute 4 outputs at a time */
120 blkCnt = blockSize >> 2U;
121
122 /* If the shift value is positive then do right shift else left shift */
123 if (sign == 0U)
124 {
125 while (blkCnt > 0U)
126 {
127 /* C = A << shiftBits */
128
129 #if defined (ARM_MATH_DSP)
130 /* Read 4 inputs */
131 in1 = *pSrc++;
132 in2 = *pSrc++;
133 in3 = *pSrc++;
134 in4 = *pSrc++;
135
136 /* Pack and store result in destination buffer (in single write) */
137 write_q7x4_ia (&pDst, __PACKq7(__SSAT(((q15_t) in1 << shiftBits), 8),
138 __SSAT(((q15_t) in2 << shiftBits), 8),
139 __SSAT(((q15_t) in3 << shiftBits), 8),
140 __SSAT(((q15_t) in4 << shiftBits), 8) ));
141 #else
142 *pDst++ = (q7_t) __SSAT(((q15_t) *pSrc++ << shiftBits), 8);
143 *pDst++ = (q7_t) __SSAT(((q15_t) *pSrc++ << shiftBits), 8);
144 *pDst++ = (q7_t) __SSAT(((q15_t) *pSrc++ << shiftBits), 8);
145 *pDst++ = (q7_t) __SSAT(((q15_t) *pSrc++ << shiftBits), 8);
146 #endif
147
148 /* Decrement loop counter */
149 blkCnt--;
150 }
151 }
152 else
153 {
154 while (blkCnt > 0U)
155 {
156 /* C = A >> shiftBits */
157
158 #if defined (ARM_MATH_DSP)
159 /* Read 4 inputs */
160 in1 = *pSrc++;
161 in2 = *pSrc++;
162 in3 = *pSrc++;
163 in4 = *pSrc++;
164
165 /* Pack and store result in destination buffer (in single write) */
166 write_q7x4_ia (&pDst, __PACKq7((in1 >> -shiftBits),
167 (in2 >> -shiftBits),
168 (in3 >> -shiftBits),
169 (in4 >> -shiftBits) ));
170 #else
171 *pDst++ = (*pSrc++ >> -shiftBits);
172 *pDst++ = (*pSrc++ >> -shiftBits);
173 *pDst++ = (*pSrc++ >> -shiftBits);
174 *pDst++ = (*pSrc++ >> -shiftBits);
175 #endif
176
177 /* Decrement loop counter */
178 blkCnt--;
179 }
180 }
181
182 /* Loop unrolling: Compute remaining outputs */
183 blkCnt = blockSize % 0x4U;
184
185 #else
186
187 /* Initialize blkCnt with number of samples */
188 blkCnt = blockSize;
189
190 #endif /* #if defined (ARM_MATH_LOOPUNROLL) */
191
192 /* If the shift value is positive then do right shift else left shift */
193 if (sign == 0U)
194 {
195 while (blkCnt > 0U)
196 {
197 /* C = A << shiftBits */
198
199 /* Shift input and store result in destination buffer. */
200 *pDst++ = (q7_t) __SSAT(((q15_t) *pSrc++ << shiftBits), 8);
201
202 /* Decrement loop counter */
203 blkCnt--;
204 }
205 }
206 else
207 {
208 while (blkCnt > 0U)
209 {
210 /* C = A >> shiftBits */
211
212 /* Shift input and store result in destination buffer. */
213 *pDst++ = (*pSrc++ >> -shiftBits);
214
215 /* Decrement loop counter */
216 blkCnt--;
217 }
218 }
219
220 }
221 #endif /* defined(ARM_MATH_MVEI) */
222
223 /**
224 @} end of BasicShift group
225 */
226
