arm_abs_q31.c

00001 /* ----------------------------------------------------------------------
00002  * Project:      CMSIS DSP Library
00003  * Title:        arm_abs_q31.c
00004  * Description:  Q31 vector absolute value
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 groupMath
00033  */
00034 
00035 /**
00036  * @addtogroup BasicAbs
00037  * @{
00038  */
00039 
00040 
00041 /**
00042  * @brief Q31 vector absolute value.
00043  * @param[in]       *pSrc points to the input buffer
00044  * @param[out]      *pDst points to the output buffer
00045  * @param[in]       blockSize number of samples in each vector
00046  * @return none.
00047  *
00048  * <b>Scaling and Overflow Behavior:</b>
00049  * \par
00050  * The function uses saturating arithmetic.
00051  * The Q31 value -1 (0x80000000) will be saturated to the maximum allowable positive value 0x7FFFFFFF.
00052  */
00053 
00054 void arm_abs_q31(
00055   q31_t * pSrc,
00056   q31_t * pDst,
00057   uint32_t blockSize)
00058 {
00059   uint32_t blkCnt;                               /* loop counter */
00060   q31_t in;                                      /* Input value */
00061 
00062 #if defined (ARM_MATH_DSP)
00063 
00064   /* Run the below code for Cortex-M4 and Cortex-M3 */
00065   q31_t in1, in2, in3, in4;
00066 
00067   /*loop Unrolling */
00068   blkCnt = blockSize >> 2U;
00069 
00070   /* First part of the processing with loop unrolling.  Compute 4 outputs at a time.
00071    ** a second loop below computes the remaining 1 to 3 samples. */
00072   while (blkCnt > 0U)
00073   {
00074     /* C = |A| */
00075     /* Calculate absolute of input (if -1 then saturated to 0x7fffffff) and then store the results in the destination buffer. */
00076     in1 = *pSrc++;
00077     in2 = *pSrc++;
00078     in3 = *pSrc++;
00079     in4 = *pSrc++;
00080 
00081     *pDst++ = (in1 > 0) ? in1 : (q31_t)__QSUB(0, in1);
00082     *pDst++ = (in2 > 0) ? in2 : (q31_t)__QSUB(0, in2);
00083     *pDst++ = (in3 > 0) ? in3 : (q31_t)__QSUB(0, in3);
00084     *pDst++ = (in4 > 0) ? in4 : (q31_t)__QSUB(0, in4);
00085 
00086     /* Decrement the loop counter */
00087     blkCnt--;
00088   }
00089 
00090   /* If the blockSize is not a multiple of 4, compute any remaining output samples here.
00091    ** No loop unrolling is used. */
00092   blkCnt = blockSize % 0x4U;
00093 
00094 #else
00095 
00096   /* Run the below code for Cortex-M0 */
00097 
00098   /* Initialize blkCnt with number of samples */
00099   blkCnt = blockSize;
00100 
00101 #endif /*   #if defined (ARM_MATH_DSP)   */
00102 
00103   while (blkCnt > 0U)
00104   {
00105     /* C = |A| */
00106     /* Calculate absolute value of the input (if -1 then saturated to 0x7fffffff) and then store the results in the destination buffer. */
00107     in = *pSrc++;
00108     *pDst++ = (in > 0) ? in : ((in == INT32_MIN) ? INT32_MAX : -in);
00109 
00110     /* Decrement the loop counter */
00111     blkCnt--;
00112   }
00113 
00114 }
00115 
00116 /**
00117  * @} end of BasicAbs group
00118  */
00119