DSP/Source/ComplexMathFunctions/arm_cmplx_mult_cmplx_f32.c

/* ----------------------------------------------------------------------
 * Project:      CMSIS DSP Library
 * Title:        arm_cmplx_mult_cmplx_f32.c
 * Description:  Floating-point complex-by-complex multiplication
 *
 * $Date:        27. January 2017
 * $Revision:    V.1.5.1
 *
 * Target Processor: Cortex-M cores
 * -------------------------------------------------------------------- */
/*
 * Copyright (C) 2010-2017 ARM Limited or its affiliates. All rights reserved.
 *
 * SPDX-License-Identifier: Apache-2.0
 *
 * Licensed under the Apache License, Version 2.0 (the License); you may
 * not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an AS IS BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#include "arm_math.h"

/**
 * @ingroup groupCmplxMath
 */

/**
 * @defgroup CmplxByCmplxMult Complex-by-Complex Multiplication
 *
 * Multiplies a complex vector by another complex vector and generates a complex result.
 * The data in the complex arrays is stored in an interleaved fashion
 * (real, imag, real, imag, ...).
 * The parameter <code>numSamples</code> represents the number of complex
 * samples processed.  The complex arrays have a total of <code>2*numSamples</code>
 * real values.
 *
 * The underlying algorithm is used:
 *
 * <pre>
 * for(n=0; n<numSamples; n++) {
 *     pDst[(2*n)+0] = pSrcA[(2*n)+0] * pSrcB[(2*n)+0] - pSrcA[(2*n)+1] * pSrcB[(2*n)+1];
 *     pDst[(2*n)+1] = pSrcA[(2*n)+0] * pSrcB[(2*n)+1] + pSrcA[(2*n)+1] * pSrcB[(2*n)+0];
 * }
 * </pre>
 *
 * There are separate functions for floating-point, Q15, and Q31 data types.
 */

/**
 * @addtogroup CmplxByCmplxMult
 * @{
 */


/**
 * @brief  Floating-point complex-by-complex multiplication
 * @param[in]  *pSrcA points to the first input vector
 * @param[in]  *pSrcB points to the second input vector
 * @param[out]  *pDst  points to the output vector
 * @param[in]  numSamples number of complex samples in each vector
 * @return none.
 */

void arm_cmplx_mult_cmplx_f32(
  float32_t * pSrcA,
  float32_t * pSrcB,
  float32_t * pDst,
  uint32_t numSamples)
{
  float32_t a1, b1, c1, d1;                      /* Temporary variables to store real and imaginary values */
  uint32_t blkCnt;                               /* loop counters */

#if defined (ARM_MATH_DSP)

  /* Run the below code for Cortex-M4 and Cortex-M3 */
  float32_t a2, b2, c2, d2;                      /* Temporary variables to store real and imaginary values */
  float32_t acc1, acc2, acc3, acc4;


  /* loop Unrolling */
  blkCnt = numSamples >> 2U;

  /* First part of the processing with loop unrolling.  Compute 4 outputs at a time.
   ** a second loop below computes the remaining 1 to 3 samples. */
  while (blkCnt > 0U)
  {
    /* C[2 * i] = A[2 * i] * B[2 * i] - A[2 * i + 1] * B[2 * i + 1].  */
    /* C[2 * i + 1] = A[2 * i] * B[2 * i + 1] + A[2 * i + 1] * B[2 * i].  */
    a1 = *pSrcA;                /* A[2 * i] */
    c1 = *pSrcB;                /* B[2 * i] */

    b1 = *(pSrcA + 1);          /* A[2 * i + 1] */
    acc1 = a1 * c1;             /* acc1 = A[2 * i] * B[2 * i] */

    a2 = *(pSrcA + 2);          /* A[2 * i + 2] */
    acc2 = (b1 * c1);           /* acc2 = A[2 * i + 1] * B[2 * i] */

    d1 = *(pSrcB + 1);          /* B[2 * i + 1] */
    c2 = *(pSrcB + 2);          /* B[2 * i + 2] */
    acc1 -= b1 * d1;            /* acc1 =      A[2 * i] * B[2 * i] - A[2 * i + 1] * B[2 * i + 1] */

    d2 = *(pSrcB + 3);          /* B[2 * i + 3] */
    acc3 = a2 * c2;             /* acc3 =       A[2 * i + 2] * B[2 * i + 2] */

    b2 = *(pSrcA + 3);          /* A[2 * i + 3] */
    acc2 += (a1 * d1);          /* acc2 =      A[2 * i + 1] * B[2 * i] + A[2 * i] * B[2 * i + 1] */

    a1 = *(pSrcA + 4);          /* A[2 * i + 4] */
    acc4 = (a2 * d2);           /* acc4 =   A[2 * i + 2] * B[2 * i + 3] */

    c1 = *(pSrcB + 4);          /* B[2 * i + 4] */
    acc3 -= (b2 * d2);          /* acc3 =       A[2 * i + 2] * B[2 * i + 2] - A[2 * i + 3] * B[2 * i + 3] */
    *pDst = acc1;               /* C[2 * i] = A[2 * i] * B[2 * i] - A[2 * i + 1] * B[2 * i + 1] */

    b1 = *(pSrcA + 5);          /* A[2 * i + 5] */
    acc4 += b2 * c2;            /* acc4 =   A[2 * i + 2] * B[2 * i + 3] + A[2 * i + 3] * B[2 * i + 2] */

    *(pDst + 1) = acc2;         /* C[2 * i + 1] = A[2 * i + 1] * B[2 * i] + A[2 * i] * B[2 * i + 1]  */
    acc1 = (a1 * c1);

    d1 = *(pSrcB + 5);
    acc2 = (b1 * c1);

    *(pDst + 2) = acc3;
    *(pDst + 3) = acc4;

    a2 = *(pSrcA + 6);
    acc1 -= (b1 * d1);

    c2 = *(pSrcB + 6);
    acc2 += (a1 * d1);

    b2 = *(pSrcA + 7);
    acc3 = (a2 * c2);

    d2 = *(pSrcB + 7);
    acc4 = (b2 * c2);

    *(pDst + 4) = acc1;
    pSrcA += 8U;

    acc3 -= (b2 * d2);
    acc4 += (a2 * d2);

    *(pDst + 5) = acc2;
    pSrcB += 8U;

    *(pDst + 6) = acc3;
    *(pDst + 7) = acc4;

    pDst += 8U;

    /* Decrement the numSamples loop counter */
    blkCnt--;
  }

  /* If the numSamples is not a multiple of 4, compute any remaining output samples here.
   ** No loop unrolling is used. */
  blkCnt = numSamples % 0x4U;

#else

  /* Run the below code for Cortex-M0 */
  blkCnt = numSamples;

#endif /* #if defined (ARM_MATH_DSP) */

  while (blkCnt > 0U)
  {
    /* C[2 * i] = A[2 * i] * B[2 * i] - A[2 * i + 1] * B[2 * i + 1].  */
    /* C[2 * i + 1] = A[2 * i] * B[2 * i + 1] + A[2 * i + 1] * B[2 * i].  */
    a1 = *pSrcA++;
    b1 = *pSrcA++;
    c1 = *pSrcB++;
    d1 = *pSrcB++;

    /* store the result in the destination buffer. */
    *pDst++ = (a1 * c1) - (b1 * d1);
    *pDst++ = (a1 * d1) + (b1 * c1);

    /* Decrement the numSamples loop counter */
    blkCnt--;
  }
}

/**
 * @} end of CmplxByCmplxMult group
 */