arm_abs_q15.c

00001 /* ----------------------------------------------------------------------    
00002 * Copyright (C) 2010-2013 ARM Limited. All rights reserved.    
00003 *    
00004 * $Date:        17. January 2013
00005 * $Revision:    V1.4.1
00006 *    
00007 * Project:      CMSIS DSP Library    
00008 * Title:        arm_abs_q15.c    
00009 *    
00010 * Description:  Q15 vector absolute value.    
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  * @addtogroup BasicAbs    
00049  * @{    
00050  */
00051 
00052 /**    
00053  * @brief Q15 vector absolute value.    
00054  * @param[in]       *pSrc points to the input buffer    
00055  * @param[out]      *pDst points to the output buffer    
00056  * @param[in]       blockSize number of samples in each vector    
00057  * @return none.    
00058  *    
00059  * <b>Scaling and Overflow Behavior:</b>    
00060  * \par    
00061  * The function uses saturating arithmetic.    
00062  * The Q15 value -1 (0x8000) will be saturated to the maximum allowable positive value 0x7FFF.    
00063  */
00064 
00065 void arm_abs_q15(
00066   q15_t * pSrc,
00067   q15_t * pDst,
00068   uint32_t blockSize)
00069 {
00070   uint32_t blkCnt;                               /* loop counter */
00071 
00072 #ifndef ARM_MATH_CM0_FAMILY
00073   __SIMD32_TYPE *simd;
00074 
00075 /* Run the below code for Cortex-M4 and Cortex-M3 */
00076 
00077   q15_t in1;                                     /* Input value1 */
00078   q15_t in2;                                     /* Input value2 */
00079 
00080 
00081   /*loop Unrolling */
00082   blkCnt = blockSize >> 2u;
00083 
00084   /* First part of the processing with loop unrolling.  Compute 4 outputs at a time.    
00085    ** a second loop below computes the remaining 1 to 3 samples. */
00086   simd = __SIMD32_CONST(pDst);
00087   while(blkCnt > 0u)
00088   {
00089     /* C = |A| */
00090     /* Read two inputs */
00091     in1 = *pSrc++;
00092     in2 = *pSrc++;
00093 
00094 
00095     /* Store the Absolute result in the destination buffer by packing the two values, in a single cycle */
00096 #ifndef  ARM_MATH_BIG_ENDIAN
00097     *simd++ =
00098       __PKHBT(((in1 > 0) ? in1 : (q15_t)__QSUB16(0, in1)),
00099               ((in2 > 0) ? in2 : (q15_t)__QSUB16(0, in2)), 16);
00100 
00101 #else
00102 
00103 
00104     *simd++ =
00105       __PKHBT(((in2 > 0) ? in2 : (q15_t)__QSUB16(0, in2)),
00106               ((in1 > 0) ? in1 : (q15_t)__QSUB16(0, in1)), 16);
00107 
00108 #endif /* #ifndef  ARM_MATH_BIG_ENDIAN    */
00109 
00110     in1 = *pSrc++;
00111     in2 = *pSrc++;
00112 
00113 
00114 #ifndef  ARM_MATH_BIG_ENDIAN
00115 
00116     *simd++ =
00117       __PKHBT(((in1 > 0) ? in1 : (q15_t)__QSUB16(0, in1)),
00118               ((in2 > 0) ? in2 : (q15_t)__QSUB16(0, in2)), 16);
00119 
00120 #else
00121 
00122 
00123     *simd++ =
00124       __PKHBT(((in2 > 0) ? in2 : (q15_t)__QSUB16(0, in2)),
00125               ((in1 > 0) ? in1 : (q15_t)__QSUB16(0, in1)), 16);
00126 
00127 #endif /* #ifndef  ARM_MATH_BIG_ENDIAN    */
00128 
00129     /* Decrement the loop counter */
00130     blkCnt--;
00131   }
00132   pDst = (q15_t *)simd;
00133     
00134   /* If the blockSize is not a multiple of 4, compute any remaining output samples here.    
00135    ** No loop unrolling is used. */
00136   blkCnt = blockSize % 0x4u;
00137 
00138   while(blkCnt > 0u)
00139   {
00140     /* C = |A| */
00141     /* Read the input */
00142     in1 = *pSrc++;
00143 
00144     /* Calculate absolute value of input and then store the result in the destination buffer. */
00145     *pDst++ = (in1 > 0) ? in1 : (q15_t)__QSUB16(0, in1);
00146 
00147     /* Decrement the loop counter */
00148     blkCnt--;
00149   }
00150 
00151 #else
00152 
00153   /* Run the below code for Cortex-M0 */
00154 
00155   q15_t in;                                      /* Temporary input variable */
00156 
00157   /* Initialize blkCnt with number of samples */
00158   blkCnt = blockSize;
00159 
00160   while(blkCnt > 0u)
00161   {
00162     /* C = |A| */
00163     /* Read the input */
00164     in = *pSrc++;
00165 
00166     /* Calculate absolute value of input and then store the result in the destination buffer. */
00167     *pDst++ = (in > 0) ? in : ((in == (q15_t) 0x8000) ? 0x7fff : -in);
00168 
00169     /* Decrement the loop counter */
00170     blkCnt--;
00171   }
00172 
00173 #endif /* #ifndef ARM_MATH_CM0_FAMILY */
00174 
00175 }
00176 
00177 /**    
00178  * @} end of BasicAbs group    
00179  */