1 /* ----------------------------------------------------------------------
2 * Project: CMSIS DSP Library
3 * Title: arm_q15_to_float.c
4 * Description: Converts the elements of the Q15 vector to floating-point vector
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 groupSupport
33 */
34
35 /**
36 * @defgroup q15_to_x Convert 16-bit Integer value
37 */
38
39 /**
40 * @addtogroup q15_to_x
41 * @{
42 */
43
44
45
46
47 /**
48 * @brief Converts the elements of the Q15 vector to floating-point vector.
49 * @param[in] *pSrc points to the Q15 input vector
50 * @param[out] *pDst points to the floating-point output vector
51 * @param[in] blockSize length of the input vector
52 * @return none.
53 *
54 * \par Description:
55 *
56 * The equation used for the conversion process is:
57 *
58 * <pre>
59 * pDst[n] = (float32_t) pSrc[n] / 32768; 0 <= n < blockSize.
60 * </pre>
61 *
62 */
63
64
arm_q15_to_float(q15_t * pSrc,float32_t * pDst,uint32_t blockSize)65 void arm_q15_to_float(
66 q15_t * pSrc,
67 float32_t * pDst,
68 uint32_t blockSize)
69 {
70 q15_t *pIn = pSrc; /* Src pointer */
71 uint32_t blkCnt; /* loop counter */
72
73
74 #if defined (ARM_MATH_DSP)
75
76 /* Run the below code for Cortex-M4 and Cortex-M3 */
77
78 /*loop Unrolling */
79 blkCnt = blockSize >> 2u;
80
81 /* First part of the processing with loop unrolling. Compute 4 outputs at a time.
82 ** a second loop below computes the remaining 1 to 3 samples. */
83 while (blkCnt > 0u)
84 {
85 /* C = (float32_t) A / 32768 */
86 /* convert from q15 to float and then store the results in the destination buffer */
87 *pDst++ = ((float32_t) * pIn++ / 32768.0f);
88 *pDst++ = ((float32_t) * pIn++ / 32768.0f);
89 *pDst++ = ((float32_t) * pIn++ / 32768.0f);
90 *pDst++ = ((float32_t) * pIn++ / 32768.0f);
91
92 /* Decrement the loop counter */
93 blkCnt--;
94 }
95
96 /* If the blockSize is not a multiple of 4, compute any remaining output samples here.
97 ** No loop unrolling is used. */
98 blkCnt = blockSize % 0x4u;
99
100 #else
101
102 /* Run the below code for Cortex-M0 */
103
104 /* Loop over blockSize number of values */
105 blkCnt = blockSize;
106
107 #endif /* #if defined (ARM_MATH_DSP) */
108
109 while (blkCnt > 0u)
110 {
111 /* C = (float32_t) A / 32768 */
112 /* convert from q15 to float and then store the results in the destination buffer */
113 *pDst++ = ((float32_t) * pIn++ / 32768.0f);
114
115 /* Decrement the loop counter */
116 blkCnt--;
117 }
118 }
119
120 /**
121 * @} end of q15_to_x group
122 */
123