arm_sub_f32.c

00001 /* ----------------------------------------------------------------------    
00002 * Copyright (C) 2010-2014 ARM Limited. All rights reserved.    
00003 *    
00004 * $Date:        19. March 2015
00005 * $Revision:    V.1.4.5
00006 *    
00007 * Project:      CMSIS DSP Library    
00008 * Title:        arm_sub_f32.c    
00009 *    
00010 * Description:  Floating-point vector subtraction.    
00011 *    
00012 * Target Processor: Cortex-M4/Cortex-M3/Cortex-M0
00013 *  
00014 * Redistribution and use in source and binary forms, with or without 
00015 * modification, are permitted provided that the following conditions
00016 * are met:
00017 *   - Redistributions of source code must retain the above copyright
00018 *     notice, this list of conditions and the following disclaimer.
00019 *   - Redistributions in binary form must reproduce the above copyright
00020 *     notice, this list of conditions and the following disclaimer in
00021 *     the documentation and/or other materials provided with the 
00022 *     distribution.
00023 *   - Neither the name of ARM LIMITED nor the names of its contributors
00024 *     may be used to endorse or promote products derived from this
00025 *     software without specific prior written permission.
00026 *
00027 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
00028 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
00029 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
00030 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE 
00031 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
00032 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
00033 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
00034 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
00035 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
00036 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
00037 * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
00038 * POSSIBILITY OF SUCH DAMAGE.  
00039 * ---------------------------------------------------------------------------- */
00040 
00041 #include "arm_math.h"
00042 
00043 /**        
00044  * @ingroup groupMath        
00045  */
00046 
00047 /**        
00048  * @defgroup BasicSub Vector Subtraction        
00049  *        
00050  * Element-by-element subtraction of two vectors.        
00051  *        
00052  * <pre>        
00053  *     pDst[n] = pSrcA[n] - pSrcB[n],   0 <= n < blockSize.        
00054  * </pre>        
00055  *        
00056  * There are separate functions for floating-point, Q7, Q15, and Q31 data types.        
00057  */
00058 
00059 /**        
00060  * @addtogroup BasicSub        
00061  * @{        
00062  */
00063 
00064 
00065 /**        
00066  * @brief Floating-point vector subtraction.        
00067  * @param[in]       *pSrcA points to the first input vector        
00068  * @param[in]       *pSrcB points to the second input vector        
00069  * @param[out]      *pDst points to the output vector        
00070  * @param[in]       blockSize number of samples in each vector        
00071  * @return none.        
00072  */
00073 
00074 void arm_sub_f32(
00075   float32_t * pSrcA,
00076   float32_t * pSrcB,
00077   float32_t * pDst,
00078   uint32_t blockSize)
00079 {
00080   uint32_t blkCnt;                               /* loop counter */
00081 
00082 #ifndef ARM_MATH_CM0_FAMILY
00083 
00084 /* Run the below code for Cortex-M4 and Cortex-M3 */
00085   float32_t inA1, inA2, inA3, inA4;              /* temporary variables */
00086   float32_t inB1, inB2, inB3, inB4;              /* temporary variables */
00087 
00088   /*loop Unrolling */
00089   blkCnt = blockSize >> 2u;
00090 
00091   /* First part of the processing with loop unrolling.  Compute 4 outputs at a time.        
00092    ** a second loop below computes the remaining 1 to 3 samples. */
00093   while(blkCnt > 0u)
00094   {
00095     /* C = A - B */
00096     /* Subtract and then store the results in the destination buffer. */
00097     /* Read 4 input samples from sourceA and sourceB */
00098     inA1 = *pSrcA;
00099     inB1 = *pSrcB;
00100     inA2 = *(pSrcA + 1);
00101     inB2 = *(pSrcB + 1);
00102     inA3 = *(pSrcA + 2);
00103     inB3 = *(pSrcB + 2);
00104     inA4 = *(pSrcA + 3);
00105     inB4 = *(pSrcB + 3);
00106 
00107     /* dst = srcA - srcB */
00108     /* subtract and store the result */
00109     *pDst = inA1 - inB1;
00110     *(pDst + 1) = inA2 - inB2;
00111     *(pDst + 2) = inA3 - inB3;
00112     *(pDst + 3) = inA4 - inB4;
00113 
00114 
00115     /* Update pointers to process next sampels */
00116     pSrcA += 4u;
00117     pSrcB += 4u;
00118     pDst += 4u;
00119 
00120     /* Decrement the loop counter */
00121     blkCnt--;
00122   }
00123 
00124   /* If the blockSize is not a multiple of 4, compute any remaining output samples here.        
00125    ** No loop unrolling is used. */
00126   blkCnt = blockSize % 0x4u;
00127 
00128 #else
00129 
00130   /* Run the below code for Cortex-M0 */
00131 
00132   /* Initialize blkCnt with number of samples */
00133   blkCnt = blockSize;
00134 
00135 #endif /* #ifndef ARM_MATH_CM0_FAMILY */
00136 
00137   while(blkCnt > 0u)
00138   {
00139     /* C = A - B */
00140     /* Subtract and then store the results in the destination buffer. */
00141     *pDst++ = (*pSrcA++) - (*pSrcB++);
00142 
00143     /* Decrement the loop counter */
00144     blkCnt--;
00145   }
00146 }
00147 
00148 /**        
00149  * @} end of BasicSub group        
00150  */