arm_cmplx_conj_q15.c

00001 /* ----------------------------------------------------------------------  
00002 * Copyright (C) 2010 ARM Limited. All rights reserved.  
00003 *  
00004 * $Date:        29. November 2010  
00005 * $Revision:    V1.0.3  
00006 *  
00007 * Project:      CMSIS DSP Library  
00008 * Title:        arm_cmplx_conj_q15.c  
00009 *  
00010 * Description:  Q15 complex conjugate.  
00011 *  
00012 * Target Processor: Cortex-M4/Cortex-M3
00013 *  
00014 * Version 1.0.3 2010/11/29 
00015 *    Re-organized the CMSIS folders and updated documentation.  
00016 *   
00017 * Version 1.0.2 2010/11/11  
00018 *    Documentation updated.   
00019 *  
00020 * Version 1.0.1 2010/10/05   
00021 *    Production release and review comments incorporated.  
00022 *  
00023 * Version 1.0.0 2010/09/20   
00024 *    Production release and review comments incorporated.  
00025 * ---------------------------------------------------------------------------- */ 
00026  
00027 #include "arm_math.h" 
00028  
00029 /**  
00030  * @ingroup groupCmplxMath  
00031  */ 
00032  
00033 /**  
00034  * @addtogroup cmplx_conj  
00035  * @{  
00036  */ 
00037  
00038 /**  
00039  * @brief  Q15 complex conjugate.  
00040  * @param  *pSrc points to the input vector  
00041  * @param  *pDst points to the output vector  
00042  * @param  numSamples number of complex samples in each vector  
00043  * @return none.  
00044  *  
00045  * <b>Scaling and Overflow Behavior:</b>  
00046  * \par  
00047  * The function uses saturating arithmetic.  
00048  * The Q15 value -1 (0x8000) will be saturated to the maximum allowable positive value 0x7FFF.  
00049  */ 
00050  
00051 void arm_cmplx_conj_q15( 
00052   q15_t * pSrc, 
00053   q15_t * pDst, 
00054   uint32_t numSamples) 
00055 { 
00056   uint32_t blkCnt;                               /* loop counter */ 
00057  
00058   /*loop Unrolling */ 
00059   blkCnt = numSamples >> 2u; 
00060  
00061   /* First part of the processing with loop unrolling.  Compute 4 outputs at a time.  
00062    ** a second loop below computes the remaining 1 to 3 samples. */ 
00063   while(blkCnt > 0u) 
00064   { 
00065     /* C[0]+jC[1] = A[0]+ j (-1) A[1] */ 
00066     /* Calculate Complex Conjugate and then store the results in the destination buffer. */ 
00067     *pDst++ = *pSrc++; 
00068     *pDst++ = __SSAT(-*pSrc++, 16); 
00069     *pDst++ = *pSrc++; 
00070     *pDst++ = __SSAT(-*pSrc++, 16); 
00071     *pDst++ = *pSrc++; 
00072     *pDst++ = __SSAT(-*pSrc++, 16); 
00073     *pDst++ = *pSrc++; 
00074     *pDst++ = __SSAT(-*pSrc++, 16); 
00075  
00076     /* Decrement the loop counter */ 
00077     blkCnt--; 
00078   } 
00079  
00080   /* If the numSamples is not a multiple of 4, compute any remaining output samples here.  
00081    ** No loop unrolling is used. */ 
00082   blkCnt = numSamples % 0x4u; 
00083  
00084   while(blkCnt > 0u) 
00085   { 
00086     /* C[0]+jC[1] = A[0]+ j (-1) A[1] */ 
00087     /* Calculate Complex Conjugate and then store the results in the destination buffer. */ 
00088     *pDst++ = *pSrc++; 
00089     *pDst++ = __SSAT(-*pSrc++, 16); 
00090  
00091     /* Decrement the loop counter */ 
00092     blkCnt--; 
00093   } 
00094 } 
00095  
00096 /**  
00097  * @} end of cmplx_conj group  
00098  */