arm_cmplx_mult_real_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_mult_real_q31.c  
00009 *  
00010 * Description:  Q31 complex by real multiplication  
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 CmplxByRealMult  
00035  * @{  
00036  */ 
00037  
00038  
00039 /**  
00040  * @brief  Q31 complex-by-real multiplication  
00041  * @param[in]  *pSrcCmplx points to the complex input vector  
00042  * @param[in]  *pSrcReal points to the real input vector  
00043  * @param[out]  *pCmplxDst points to the complex output vector  
00044  * @param[in]  numSamples number of samples in each vector  
00045  * @return none.  
00046  *  
00047  * <b>Scaling and Overflow Behavior:</b>  
00048  * \par  
00049  * The function uses saturating arithmetic.  
00050  * Results outside of the allowable Q31 range[0x80000000 0x7FFFFFFF] will be saturated.  
00051  */ 
00052  
00053 void arm_cmplx_mult_real_q31( 
00054   q31_t * pSrcCmplx, 
00055   q31_t * pSrcReal, 
00056   q31_t * pCmplxDst, 
00057   uint32_t numSamples) 
00058 { 
00059   q31_t in;                                      /* Temporary variable to store input value */ 
00060   uint32_t blkCnt;                               /* loop counters */ 
00061  
00062   /* loop Unrolling */ 
00063   blkCnt = numSamples >> 2u; 
00064  
00065   /* First part of the processing with loop unrolling.  Compute 4 outputs at a time.  
00066    ** a second loop below computes the remaining 1 to 3 samples. */ 
00067   while(blkCnt > 0u) 
00068   { 
00069     /* C[2 * i] = A[2 * i] * B[i].            */ 
00070     /* C[2 * i + 1] = A[2 * i + 1] * B[i].        */ 
00071     in = *pSrcReal++; 
00072     /* store the result in the destination buffer. */ 
00073     *pCmplxDst++ = (q31_t) clip_q63_to_q31(((q63_t) * pSrcCmplx++ * in) >> 31); 
00074     *pCmplxDst++ = (q31_t) clip_q63_to_q31(((q63_t) * pSrcCmplx++ * in) >> 31); 
00075  
00076     in = *pSrcReal++; 
00077     *pCmplxDst++ = (q31_t) clip_q63_to_q31(((q63_t) * pSrcCmplx++ * in) >> 31); 
00078     *pCmplxDst++ = (q31_t) clip_q63_to_q31(((q63_t) * pSrcCmplx++ * in) >> 31); 
00079  
00080     in = *pSrcReal++; 
00081     *pCmplxDst++ = (q31_t) clip_q63_to_q31(((q63_t) * pSrcCmplx++ * in) >> 31); 
00082     *pCmplxDst++ = (q31_t) clip_q63_to_q31(((q63_t) * pSrcCmplx++ * in) >> 31); 
00083  
00084     in = *pSrcReal++; 
00085     *pCmplxDst++ = (q31_t) clip_q63_to_q31(((q63_t) * pSrcCmplx++ * in) >> 31); 
00086     *pCmplxDst++ = (q31_t) clip_q63_to_q31(((q63_t) * pSrcCmplx++ * in) >> 31); 
00087  
00088     /* Decrement the numSamples loop counter */ 
00089     blkCnt--; 
00090   } 
00091  
00092   /* If the numSamples is not a multiple of 4, compute any remaining output samples here.  
00093    ** No loop unrolling is used. */ 
00094   blkCnt = numSamples % 0x4u; 
00095  
00096   while(blkCnt > 0u) 
00097   { 
00098     /* C[2 * i] = A[2 * i] * B[i].            */ 
00099     /* C[2 * i + 1] = A[2 * i + 1] * B[i].        */ 
00100     in = *pSrcReal++; 
00101     /* store the result in the destination buffer. */ 
00102     *pCmplxDst++ = (q31_t) clip_q63_to_q31(((q63_t) * pSrcCmplx++ * in) >> 31); 
00103     *pCmplxDst++ = (q31_t) clip_q63_to_q31(((q63_t) * pSrcCmplx++ * in) >> 31); 
00104  
00105     /* Decrement the numSamples loop counter */ 
00106     blkCnt--; 
00107   } 
00108 } 
00109  
00110 /**  
00111  * @} end of CmplxByRealMult group  
00112  */