arm_cmplx_conj_q31.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_q31.c  
00009 *  
00010 * Description:  Q31 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  Q31 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 Q31 value -1 (0x80000000) will be saturated to the maximum allowable positive value 0x7FFFFFFF.  
00049  */ 
00050  
00051 void arm_cmplx_conj_q31( 
00052   q31_t * pSrc, 
00053   q31_t * pDst, 
00054   uint32_t numSamples) 
00055 { 
00056   uint32_t blkCnt;                               /* loop counter */ 
00057   q31_t in;                                      /* Input value */ 
00058  
00059   /*loop Unrolling */ 
00060   blkCnt = numSamples >> 2u; 
00061  
00062   /* First part of the processing with loop unrolling.  Compute 4 outputs at a time.  
00063    ** a second loop below computes the remaining 1 to 3 samples. */ 
00064   while(blkCnt > 0u) 
00065   { 
00066     /* C[0]+jC[1] = A[0]+ j (-1) A[1] */ 
00067     /* Calculate Complex Conjugate and then store the results in the destination buffer. */ 
00068     /* Saturated to 0x7fffffff if the input is -1(0x80000000)*/ 
00069     *pDst++ = *pSrc++; 
00070     in = *pSrc++; 
00071     *pDst++ = (in == 0x80000000) ? 0x7fffffff : -in; 
00072     *pDst++ = *pSrc++; 
00073     in = *pSrc++; 
00074     *pDst++ = (in == 0x80000000) ? 0x7fffffff : -in; 
00075     *pDst++ = *pSrc++; 
00076     in = *pSrc++; 
00077     *pDst++ = (in == 0x80000000) ? 0x7fffffff : -in; 
00078     *pDst++ = *pSrc++; 
00079     in = *pSrc++; 
00080     *pDst++ = (in == 0x80000000) ? 0x7fffffff : -in; 
00081  
00082     /* Decrement the loop counter */ 
00083     blkCnt--; 
00084   } 
00085  
00086   /* If the numSamples is not a multiple of 4, compute any remaining output samples here.  
00087    ** No loop unrolling is used. */ 
00088   blkCnt = numSamples % 0x4u; 
00089  
00090   while(blkCnt > 0u) 
00091   { 
00092     /* C[0]+jC[1] = A[0]+ j (-1) A[1] */ 
00093     /* Calculate Complex Conjugate and then store the results in the destination buffer. */ 
00094     /* Saturated to 0x7fffffff if the input is -1(0x80000000)*/ 
00095     *pDst++ = *pSrc++; 
00096     in = *pSrc++; 
00097     *pDst++ = (in == 0x80000000) ? 0x7fffffff : -in; 
00098  
00099     /* Decrement the loop counter */ 
00100     blkCnt--; 
00101   } 
00102 } 
00103  
00104 /**  
00105  * @} end of cmplx_conj group  
00106  */