arm_negate_f32.c

00001 /* ----------------------------------------------------------------------
00002  * Project:      CMSIS DSP Library
00003  * Title:        arm_negate_f32.c
00004  * Description:  Negates floating-point vectors
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  * @defgroup negate Vector Negate
00037  *
00038  * Negates the elements of a vector.
00039  *
00040  * <pre>
00041  *     pDst[n] = -pSrc[n],   0 <= n < blockSize.
00042  * </pre>
00043  *
00044  * The functions support in-place computation allowing the source and
00045  * destination pointers to reference the same memory buffer.
00046  * There are separate functions for floating-point, Q7, Q15, and Q31 data types.
00047  */
00048 
00049 /**
00050  * @addtogroup negate
00051  * @{
00052  */
00053 
00054 /**
00055  * @brief  Negates the elements of a floating-point vector.
00056  * @param[in]  *pSrc points to the input vector
00057  * @param[out]  *pDst points to the output vector
00058  * @param[in]  blockSize number of samples in the vector
00059  * @return none.
00060  */
00061 
00062 void arm_negate_f32(
00063   float32_t * pSrc,
00064   float32_t * pDst,
00065   uint32_t blockSize)
00066 {
00067   uint32_t blkCnt;                               /* loop counter */
00068 
00069 
00070 #if defined (ARM_MATH_DSP)
00071 
00072 /* Run the below code for Cortex-M4 and Cortex-M3 */
00073   float32_t in1, in2, in3, in4;                  /* temporary variables */
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     /* read inputs from source */
00083     in1 = *pSrc;
00084     in2 = *(pSrc + 1);
00085     in3 = *(pSrc + 2);
00086     in4 = *(pSrc + 3);
00087 
00088     /* negate the input */
00089     in1 = -in1;
00090     in2 = -in2;
00091     in3 = -in3;
00092     in4 = -in4;
00093 
00094     /* store the result to destination */
00095     *pDst = in1;
00096     *(pDst + 1) = in2;
00097     *(pDst + 2) = in3;
00098     *(pDst + 3) = in4;
00099 
00100     /* update pointers to process next samples */
00101     pSrc += 4U;
00102     pDst += 4U;
00103 
00104     /* Decrement the loop counter */
00105     blkCnt--;
00106   }
00107 
00108   /* If the blockSize is not a multiple of 4, compute any remaining output samples here.
00109    ** No loop unrolling is used. */
00110   blkCnt = blockSize % 0x4U;
00111 
00112 #else
00113 
00114   /* Run the below code for Cortex-M0 */
00115 
00116   /* Initialize blkCnt with number of samples */
00117   blkCnt = blockSize;
00118 
00119 #endif /* #if defined (ARM_MATH_DSP) */
00120 
00121   while (blkCnt > 0U)
00122   {
00123     /* C = -A */
00124     /* Negate and then store the results in the destination buffer. */
00125     *pDst++ = -*pSrc++;
00126 
00127     /* Decrement the loop counter */
00128     blkCnt--;
00129   }
00130 }
00131 
00132 /**
00133  * @} end of negate group
00134  */
00135