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# arm_cmplx_mult_cmplx_q15.c

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    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_cmplx_q15.c
    00009 *
    00010 * Description:  Q15 complex-by-complex 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
    00051 void arm_cmplx_mult_cmplx_q15(
    00052   q15_t * pSrcA,
    00053   q15_t * pSrcB,
    00054   q15_t * pDst,
    00055   uint32_t numSamples)
    00056 {
    00057   q15_t a, b, c, d;                              /* Temporary variables to store real and imaginary values */
    00058   uint32_t blkCnt;                               /* loop counters */
    00059
    00060   /* loop Unrolling */
    00061   blkCnt = numSamples >> 2u;
    00062
    00063   /* First part of the processing with loop unrolling.  Compute 4 outputs at a time.
    00064    ** a second loop below computes the remaining 1 to 3 samples. */
    00065   while(blkCnt > 0u)
    00066   {
    00067     /* C[2 * i] = A[2 * i] * B[2 * i] - A[2 * i + 1] * B[2 * i + 1].  */
    00068     /* C[2 * i + 1] = A[2 * i] * B[2 * i + 1] + A[2 * i + 1] * B[2 * i].  */
    00069     a = *pSrcA++;
    00070     b = *pSrcA++;
    00071     c = *pSrcB++;
    00072     d = *pSrcB++;
    00073
    00074     /* store the result in 3.13 format in the destination buffer. */
    00075     *pDst++ =
    00076       (q15_t) (q31_t) (((q31_t) a * c) >> 17) - (((q31_t) b * d) >> 17);
    00077     /* store the result in 3.13 format in the destination buffer. */
    00078     *pDst++ =
    00079       (q15_t) (q31_t) (((q31_t) a * d) >> 17) + (((q31_t) b * c) >> 17);
    00080
    00081     a = *pSrcA++;
    00082     b = *pSrcA++;
    00083     c = *pSrcB++;
    00084     d = *pSrcB++;
    00085
    00086     /* store the result in 3.13 format in the destination buffer. */
    00087     *pDst++ =
    00088       (q15_t) (q31_t) (((q31_t) a * c) >> 17) - (((q31_t) b * d) >> 17);
    00089     /* store the result in 3.13 format in the destination buffer. */
    00090     *pDst++ =
    00091       (q15_t) (q31_t) (((q31_t) a * d) >> 17) + (((q31_t) b * c) >> 17);
    00092
    00093     a = *pSrcA++;
    00094     b = *pSrcA++;
    00095     c = *pSrcB++;
    00096     d = *pSrcB++;
    00097
    00098     /* store the result in 3.13 format in the destination buffer. */
    00099     *pDst++ =
    00100       (q15_t) (q31_t) (((q31_t) a * c) >> 17) - (((q31_t) b * d) >> 17);
    00101     /* store the result in 3.13 format in the destination buffer. */
    00102     *pDst++ =
    00103       (q15_t) (q31_t) (((q31_t) a * d) >> 17) + (((q31_t) b * c) >> 17);
    00104
    00105     a = *pSrcA++;
    00106     b = *pSrcA++;
    00107     c = *pSrcB++;
    00108     d = *pSrcB++;
    00109
    00110     /* store the result in 3.13 format in the destination buffer. */
    00111     *pDst++ =
    00112       (q15_t) (q31_t) (((q31_t) a * c) >> 17) - (((q31_t) b * d) >> 17);
    00113     /* store the result in 3.13 format in the destination buffer. */
    00114     *pDst++ =
    00115       (q15_t) (q31_t) (((q31_t) a * d) >> 17) + (((q31_t) b * c) >> 17);
    00116
    00117     /* Decrement the blockSize loop counter */
    00118     blkCnt--;
    00119   }
    00120
    00121   /* If the blockSize is not a multiple of 4, compute any remaining output samples here.
    00122    ** No loop unrolling is used. */
    00123   blkCnt = numSamples % 0x4u;
    00124
    00125   while(blkCnt > 0u)
    00126   {
    00127     /* C[2 * i] = A[2 * i] * B[2 * i] - A[2 * i + 1] * B[2 * i + 1].  */
    00128     /* C[2 * i + 1] = A[2 * i] * B[2 * i + 1] + A[2 * i + 1] * B[2 * i].  */
    00129     a = *pSrcA++;
    00130     b = *pSrcA++;
    00131     c = *pSrcB++;
    00132     d = *pSrcB++;
    00133
    00134     /* store the result in 3.13 format in the destination buffer. */
    00135     *pDst++ =
    00136       (q15_t) (q31_t) (((q31_t) a * c) >> 17) - (((q31_t) b * d) >> 17);
    00137     /* store the result in 3.13 format in the destination buffer. */
    00138     *pDst++ =
    00139       (q15_t) (q31_t) (((q31_t) a * d) >> 17) + (((q31_t) b * c) >> 17);
    00140
    00141     /* Decrement the blockSize loop counter */
    00142     blkCnt--;
    00143   }
    00144 }
    00145

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