CMSIS-DSP/Source/ComplexMathFunctions/arm_cmplx_mult_cmplx_f16.c

/* ----------------------------------------------------------------------
 * Project:      CMSIS DSP Library
 * Title:        arm_cmplx_mult_cmplx_f16.c
 * Description:  Floating-point complex-by-complex multiplication
 *
 * $Date:        18. March 2019
 * $Revision:    V1.6.0
 *
 * Target Processor: Cortex-M cores
 * -------------------------------------------------------------------- */
/*
 * Copyright (C) 2010-2019 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 "dsp/complex_math_functions_f16.h"

#if defined(ARM_FLOAT16_SUPPORTED)

/**
  @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 first input vector
  @param[in]     pSrcB       points to second input vector
  @param[out]    pDst        points to output vector
  @param[in]     numSamples  number of samples in each vector
  @return        none
 */

#if defined(ARM_MATH_MVEF) && !defined(ARM_MATH_AUTOVECTORIZE)

void arm_cmplx_mult_cmplx_f16(
  const float16_t * pSrcA,
  const float16_t * pSrcB,
        float16_t * pDst,
        uint32_t numSamples)
{
    int32_t  blkCnt;           /* loop counters */
    int32_t  blockSize = numSamples;
    f16x8_t vecA;
    f16x8_t vecB;
    f16x8_t vecDst;

    blkCnt = blockSize * CMPLX_DIM;
    blkCnt = blkCnt >> 3;

    while (blkCnt > 0) 
    {
        vecA = vldrhq_f16(pSrcA);
        vecB = vldrhq_f16(pSrcB);
        /* C[2 * i] = A[2 * i] * B[2 * i] - A[2 * i + 1] * B[2 * i + 1].  */
        vecDst = vcmulq(vecA, vecB);
        /* C[2 * i + 1] = A[2 * i] * B[2 * i + 1] + A[2 * i + 1] * B[2 * i].  */
        vecDst = vcmlaq_rot90(vecDst, vecA, vecB);
        vstrhq_f16(pDst, vecDst);

        blkCnt--;
        pSrcA += 8;
        pSrcB += 8;
        pDst += 8;
    }

    _Float16 a, b, c, d;  /* Temporary variables to store real and imaginary values */
        /* Tail */
    blkCnt = (blockSize & 7) >> 1;
    while (blkCnt > 0)
    {
      /* 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    ]. */

      a = *pSrcA++;
      b = *pSrcA++;
      c = *pSrcB++;
      d = *pSrcB++;

      /* store result in destination buffer. */
      *pDst++ = (a * c) - (b * d);
      *pDst++ = (a * d) + (b * c);

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


#else
void arm_cmplx_mult_cmplx_f16(
  const float16_t * pSrcA,
  const float16_t * pSrcB,
        float16_t * pDst,
        uint32_t numSamples)
{
    uint32_t blkCnt;                               /* Loop counter */
    _Float16 a, b, c, d;  /* Temporary variables to store real and imaginary values */

#if defined (ARM_MATH_LOOPUNROLL) && !defined(ARM_MATH_AUTOVECTORIZE)

  /* Loop unrolling: Compute 4 outputs at a time */
  blkCnt = numSamples >> 2U;

  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    ]. */

    a = *pSrcA++;
    b = *pSrcA++;
    c = *pSrcB++;
    d = *pSrcB++;
    /* store result in destination buffer. */
    *pDst++ = (a * c) - (b * d);
    *pDst++ = (a * d) + (b * c);

    a = *pSrcA++;
    b = *pSrcA++;
    c = *pSrcB++;
    d = *pSrcB++;
    *pDst++ = (a * c) - (b * d);
    *pDst++ = (a * d) + (b * c);

    a = *pSrcA++;
    b = *pSrcA++;
    c = *pSrcB++;
    d = *pSrcB++;
    *pDst++ = (a * c) - (b * d);
    *pDst++ = (a * d) + (b * c);

    a = *pSrcA++;
    b = *pSrcA++;
    c = *pSrcB++;
    d = *pSrcB++;
    *pDst++ = (a * c) - (b * d);
    *pDst++ = (a * d) + (b * c);

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

  /* Loop unrolling: Compute remaining outputs */
  blkCnt = numSamples % 0x4U;

#else

  /* Initialize blkCnt with number of samples */
  blkCnt = numSamples;

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

  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    ]. */

    a = *pSrcA++;
    b = *pSrcA++;
    c = *pSrcB++;
    d = *pSrcB++;

    /* store result in destination buffer. */
    *pDst++ = (a * c) - (b * d);
    *pDst++ = (a * d) + (b * c);

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

}
#endif /* defined(ARM_MATH_MVEF) && !defined(ARM_MATH_AUTOVECTORIZE) */

/**
  @} end of CmplxByCmplxMult group
 */

#endif /* #if defined(ARM_FLOAT16_SUPPORTED) */