arm_q15_to_float.c

00001 /* ----------------------------------------------------------------------
00002  * Project:      CMSIS DSP Library
00003  * Title:        arm_q15_to_float.c
00004  * Description:  Converts the elements of the Q15 vector to floating-point vector
00005  *
00006  * $Date:        27. January 2017
00007  * $Revision:    V.1.5.1
00008  *
00009  * Target Processor: Cortex-M cores
00010  * -------------------------------------------------------------------- */
00011 /*
00012  * Copyright (C) 2010-2017 ARM Limited or its affiliates. All rights reserved.
00013  *
00014  * SPDX-License-Identifier: Apache-2.0
00015  *
00016  * Licensed under the Apache License, Version 2.0 (the License); you may
00017  * not use this file except in compliance with the License.
00018  * You may obtain a copy of the License at
00019  *
00020  * www.apache.org/licenses/LICENSE-2.0
00021  *
00022  * Unless required by applicable law or agreed to in writing, software
00023  * distributed under the License is distributed on an AS IS BASIS, WITHOUT
00024  * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
00025  * See the License for the specific language governing permissions and
00026  * limitations under the License.
00027  */
00028 
00029 #include "arm_math.h"
00030 
00031 /**
00032  * @ingroup groupSupport
00033  */
00034 
00035 /**
00036  * @defgroup q15_to_x  Convert 16-bit Integer value
00037  */
00038 
00039 /**
00040  * @addtogroup q15_to_x
00041  * @{
00042  */
00043 
00044 
00045 
00046 
00047 /**
00048  * @brief  Converts the elements of the Q15 vector to floating-point vector.
00049  * @param[in]       *pSrc points to the Q15 input vector
00050  * @param[out]      *pDst points to the floating-point output vector
00051  * @param[in]       blockSize length of the input vector
00052  * @return none.
00053  *
00054  * \par Description:
00055  *
00056  * The equation used for the conversion process is:
00057  *
00058  * <pre>
00059  *  pDst[n] = (float32_t) pSrc[n] / 32768;   0 <= n < blockSize.
00060  * </pre>
00061  *
00062  */
00063 
00064 
00065 void arm_q15_to_float(
00066   q15_t * pSrc,
00067   float32_t * pDst,
00068   uint32_t blockSize)
00069 {
00070   q15_t *pIn = pSrc;                             /* Src pointer */
00071   uint32_t blkCnt;                               /* loop counter */
00072 
00073 
00074 #if defined (ARM_MATH_DSP)
00075 
00076   /* Run the below code for Cortex-M4 and Cortex-M3 */
00077 
00078   /*loop Unrolling */
00079   blkCnt = blockSize >> 2U;
00080 
00081   /* First part of the processing with loop unrolling.  Compute 4 outputs at a time.
00082    ** a second loop below computes the remaining 1 to 3 samples. */
00083   while (blkCnt > 0U)
00084   {
00085     /* C = (float32_t) A / 32768 */
00086     /* convert from q15 to float and then store the results in the destination buffer */
00087     *pDst++ = ((float32_t) * pIn++ / 32768.0f);
00088     *pDst++ = ((float32_t) * pIn++ / 32768.0f);
00089     *pDst++ = ((float32_t) * pIn++ / 32768.0f);
00090     *pDst++ = ((float32_t) * pIn++ / 32768.0f);
00091 
00092     /* Decrement the loop counter */
00093     blkCnt--;
00094   }
00095 
00096   /* If the blockSize is not a multiple of 4, compute any remaining output samples here.
00097    ** No loop unrolling is used. */
00098   blkCnt = blockSize % 0x4U;
00099 
00100 #else
00101 
00102   /* Run the below code for Cortex-M0 */
00103 
00104   /* Loop over blockSize number of values */
00105   blkCnt = blockSize;
00106 
00107 #endif /* #if defined (ARM_MATH_DSP) */
00108 
00109   while (blkCnt > 0U)
00110   {
00111     /* C = (float32_t) A / 32768 */
00112     /* convert from q15 to float and then store the results in the destination buffer */
00113     *pDst++ = ((float32_t) * pIn++ / 32768.0f);
00114 
00115     /* Decrement the loop counter */
00116     blkCnt--;
00117   }
00118 }
00119 
00120 /**
00121  * @} end of q15_to_x group
00122  */
00123