1 /* ----------------------------------------------------------------------
2 * Project: CMSIS DSP Library
3 * Title: arm_q31_to_float.c
4 * Description: Converts the elements of the Q31 vector to floating-point vector
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/support_functions.h"
30
31 /**
32 @ingroup groupSupport
33 */
34
35 /**
36 * @defgroup q31_to_x Convert 32-bit fixed point value
37 */
38
39 /**
40 @addtogroup q31_to_x
41 @{
42 */
43
44 /**
45 @brief Converts the elements of the Q31 vector to floating-point vector.
46 @param[in] pSrc points to the Q31 input vector
47 @param[out] pDst points to the floating-point output vector
48 @param[in] blockSize number of samples in each vector
49
50 @par Details
51 The equation used for the conversion process is:
52 <pre>
53 pDst[n] = (float32_t) pSrc[n] / 2147483648; 0 <= n < blockSize.
54 </pre>
55 */
56 #if defined(ARM_MATH_MVEF) && !defined(ARM_MATH_AUTOVECTORIZE)
arm_q31_to_float(const q31_t * pSrc,float32_t * pDst,uint32_t blockSize)57 ARM_DSP_ATTRIBUTE void arm_q31_to_float(
58 const q31_t * pSrc,
59 float32_t * pDst,
60 uint32_t blockSize)
61 {
62 uint32_t blkCnt; /* loop counters */
63 q31x4_t vecDst;
64 q31_t const *pSrcVec;
65
66 pSrcVec = (q31_t const *) pSrc;
67 blkCnt = blockSize >> 2;
68 while (blkCnt > 0U)
69 {
70 /* C = (float32_t) A / 2147483648 */
71 /* convert from q31 to float and then store the results in the destination buffer */
72 vecDst = vld1q(pSrcVec);
73 pSrcVec += 4;
74 vstrwq(pDst, vcvtq_n_f32_s32(vecDst, 31));
75 pDst += 4;
76 /*
77 * Decrement the blockSize loop counter
78 */
79 blkCnt--;
80 }
81 /*
82 * tail
83 * (will be merged thru tail predication)
84 */
85 blkCnt = blockSize & 3;
86 while (blkCnt > 0U)
87 {
88 /* C = (float32_t) A / 2147483648 */
89
90 /* Convert from q31 to float and store result in destination buffer */
91 *pDst++ = ((float32_t) *pSrcVec++ / 2147483648.0f);
92
93 /* Decrement loop counter */
94 blkCnt--;
95 }
96 }
97
98 #else
99 #if defined(ARM_MATH_NEON_EXPERIMENTAL)
arm_q31_to_float(const q31_t * pSrc,float32_t * pDst,uint32_t blockSize)100 ARM_DSP_ATTRIBUTE void arm_q31_to_float(
101 const q31_t * pSrc,
102 float32_t * pDst,
103 uint32_t blockSize)
104 {
105 const q31_t *pIn = pSrc; /* Src pointer */
106 uint32_t blkCnt; /* loop counter */
107
108 int32x4_t inV;
109 float32x4_t outV;
110
111 blkCnt = blockSize >> 2U;
112
113 /* Compute 4 outputs at a time.
114 ** a second loop below computes the remaining 1 to 3 samples. */
115 while (blkCnt > 0U)
116 {
117 /* C = (float32_t) A / 2147483648 */
118 /* Convert from q31 to float and then store the results in the destination buffer */
119 inV = vld1q_s32(pIn);
120 pIn += 4;
121
122 outV = vcvtq_n_f32_s32(inV,31);
123
124 vst1q_f32(pDst, outV);
125 pDst += 4;
126
127 /* Decrement the loop counter */
128 blkCnt--;
129 }
130
131 /* If the blockSize is not a multiple of 4, compute any remaining output samples here.
132 ** No loop unrolling is used. */
133 blkCnt = blockSize & 3;
134
135
136 while (blkCnt > 0U)
137 {
138 /* C = (float32_t) A / 2147483648 */
139 /* Convert from q31 to float and then store the results in the destination buffer */
140 *pDst++ = ((float32_t) * pIn++ / 2147483648.0f);
141
142 /* Decrement the loop counter */
143 blkCnt--;
144 }
145 }
146 #else
arm_q31_to_float(const q31_t * pSrc,float32_t * pDst,uint32_t blockSize)147 ARM_DSP_ATTRIBUTE void arm_q31_to_float(
148 const q31_t * pSrc,
149 float32_t * pDst,
150 uint32_t blockSize)
151 {
152 const q31_t *pIn = pSrc; /* Src pointer */
153 uint32_t blkCnt; /* loop counter */
154
155 #if defined (ARM_MATH_LOOPUNROLL)
156
157 /* Loop unrolling */
158 blkCnt = blockSize >> 2U;
159
160 while (blkCnt > 0U)
161 {
162 /* C = (float32_t) A / 2147483648 */
163
164 /* Convert from q31 to float and store result in destination buffer */
165 *pDst++ = ((float32_t) *pIn++ / 2147483648.0f);
166 *pDst++ = ((float32_t) *pIn++ / 2147483648.0f);
167 *pDst++ = ((float32_t) *pIn++ / 2147483648.0f);
168 *pDst++ = ((float32_t) *pIn++ / 2147483648.0f);
169
170 /* Decrement loop counter */
171 blkCnt--;
172 }
173
174 /* Loop unrolling: Compute remaining outputs */
175 blkCnt = blockSize % 0x4U;
176
177 #else
178
179 /* Initialize blkCnt with number of samples */
180 blkCnt = blockSize;
181
182 #endif /* #if defined (ARM_MATH_LOOPUNROLL) */
183
184 while (blkCnt > 0U)
185 {
186 /* C = (float32_t) A / 2147483648 */
187
188 /* Convert from q31 to float and store result in destination buffer */
189 *pDst++ = ((float32_t) *pIn++ / 2147483648.0f);
190
191 /* Decrement loop counter */
192 blkCnt--;
193 }
194
195 }
196 #endif /* #if defined(ARM_MATH_NEON) */
197 #endif /* defined(ARM_MATH_MVEF) && !defined(ARM_MATH_AUTOVECTORIZE) */
198
199 /**
200 @} end of q31_to_x group
201 */
202
