arm_q31_to_float.c

00001 /* ----------------------------------------------------------------------
00002  * Project:      CMSIS DSP Library
00003  * Title:        arm_q31_to_float.c
00004  * Description:  Converts the elements of the Q31 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 q31_to_x  Convert 32-bit Integer value
00037  */
00038 
00039 /**
00040  * @addtogroup q31_to_x
00041  * @{
00042  */
00043 
00044 /**
00045  * @brief Converts the elements of the Q31 vector to floating-point vector.
00046  * @param[in]       *pSrc points to the Q31 input vector
00047  * @param[out]      *pDst points to the floating-point output vector
00048  * @param[in]       blockSize length of the input vector
00049  * @return none.
00050  *
00051  * \par Description:
00052  *
00053  * The equation used for the conversion process is:
00054  *
00055  * <pre>
00056  *  pDst[n] = (float32_t) pSrc[n] / 2147483648;   0 <= n < blockSize.
00057  * </pre>
00058  *
00059  */
00060 
00061 
00062 void arm_q31_to_float(
00063   q31_t * pSrc,
00064   float32_t * pDst,
00065   uint32_t blockSize)
00066 {
00067   q31_t *pIn = pSrc;                             /* Src pointer */
00068   uint32_t blkCnt;                               /* loop counter */
00069 
00070 
00071 #if defined (ARM_MATH_DSP)
00072 
00073   /* Run the below code for Cortex-M4 and Cortex-M3 */
00074 
00075   /*loop Unrolling */
00076   blkCnt = blockSize >> 2U;
00077 
00078   /* First part of the processing with loop unrolling.  Compute 4 outputs at a time.
00079    ** a second loop below computes the remaining 1 to 3 samples. */
00080   while (blkCnt > 0U)
00081   {
00082     /* C = (float32_t) A / 2147483648 */
00083     /* convert from q31 to float and then store the results in the destination buffer */
00084     *pDst++ = ((float32_t) * pIn++ / 2147483648.0f);
00085     *pDst++ = ((float32_t) * pIn++ / 2147483648.0f);
00086     *pDst++ = ((float32_t) * pIn++ / 2147483648.0f);
00087     *pDst++ = ((float32_t) * pIn++ / 2147483648.0f);
00088 
00089     /* Decrement the loop counter */
00090     blkCnt--;
00091   }
00092 
00093   /* If the blockSize is not a multiple of 4, compute any remaining output samples here.
00094    ** No loop unrolling is used. */
00095   blkCnt = blockSize % 0x4U;
00096 
00097 #else
00098 
00099   /* Run the below code for Cortex-M0 */
00100 
00101   /* Loop over blockSize number of values */
00102   blkCnt = blockSize;
00103 
00104 #endif /* #if defined (ARM_MATH_DSP) */
00105 
00106   while (blkCnt > 0U)
00107   {
00108     /* C = (float32_t) A / 2147483648 */
00109     /* convert from q31 to float and then store the results in the destination buffer */
00110     *pDst++ = ((float32_t) * pIn++ / 2147483648.0f);
00111 
00112     /* Decrement the loop counter */
00113     blkCnt--;
00114   }
00115 }
00116 
00117 /**
00118  * @} end of q31_to_x group
00119  */
00120