text: /* ----------------------------------------------------------------------
   * Project:      CMSIS DSP Library
   * Title:        arm_cmplx_mult_real_q15.c
   * Description:  Q15 complex by real 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
   */
  
  /**
   * @addtogroup CmplxByRealMult
   * @{
   */
  
  
  /**
   * @brief  Q15 complex-by-real multiplication
   * @param[in]  *pSrcCmplx points to the complex input vector
   * @param[in]  *pSrcReal points to the real input vector
   * @param[out]  *pCmplxDst points to the complex output vector
   * @param[in]  numSamples number of samples in each vector
   * @return none.
   *
   * <b>Scaling and Overflow Behavior:</b>
   * \par
   * The function uses saturating arithmetic.
   * Results outside of the allowable Q15 range [0x8000 0x7FFF] will be saturated.
   */
  
  void arm_cmplx_mult_real_q15(
    q15_t * pSrcCmplx,
    q15_t * pSrcReal,
    q15_t * pCmplxDst,
    uint32_t numSamples)
  {
    q15_t in;                                      /* Temporary variable to store input value */
  
  #if defined (ARM_MATH_DSP)
  
    /* Run the below code for Cortex-M4 and Cortex-M3 */
    uint32_t blkCnt;                               /* loop counters */
    q31_t inA1, inA2;                              /* Temporary variables to hold input data */
    q31_t inB1;                                    /* Temporary variables to hold input data */
    q15_t out1, out2, out3, out4;                  /* Temporary variables to hold output data */
    q31_t mul1, mul2, mul3, mul4;                  /* Temporary variables to hold intermediate data */
  
    /* 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[i].            */
      /* C[2 * i + 1] = A[2 * i + 1] * B[i].        */
      /* read complex number both real and imaginary from complex input buffer */
      inA1 = *__SIMD32(pSrcCmplx)++;
      /* read two real values at a time from real input buffer */
      inB1 = *__SIMD32(pSrcReal)++;
      /* read complex number both real and imaginary from complex input buffer */
      inA2 = *__SIMD32(pSrcCmplx)++;
  
      /* multiply complex number with real numbers */
  #ifndef ARM_MATH_BIG_ENDIAN
  
      mul1 = (q31_t) ((q15_t) (inA1) * (q15_t) (inB1));
      mul2 = (q31_t) ((q15_t) (inA1 >> 16) * (q15_t) (inB1));
      mul3 = (q31_t) ((q15_t) (inA2) * (q15_t) (inB1 >> 16));
      mul4 = (q31_t) ((q15_t) (inA2 >> 16) * (q15_t) (inB1 >> 16));
  
  #else
  
      mul2 = (q31_t) ((q15_t) (inA1 >> 16) * (q15_t) (inB1 >> 16));
      mul1 = (q31_t) ((q15_t) inA1 * (q15_t) (inB1 >> 16));
      mul4 = (q31_t) ((q15_t) (inA2 >> 16) * (q15_t) inB1);
      mul3 = (q31_t) ((q15_t) inA2 * (q15_t) inB1);
  
  #endif /* #ifndef ARM_MATH_BIG_ENDIAN */
  
      /* saturate the result */
      out1 = (q15_t) __SSAT(mul1 >> 15u, 16);
      out2 = (q15_t) __SSAT(mul2 >> 15u, 16);
      out3 = (q15_t) __SSAT(mul3 >> 15u, 16);
      out4 = (q15_t) __SSAT(mul4 >> 15u, 16);
  
      /* pack real and imaginary outputs and store them to destination */
      *__SIMD32(pCmplxDst)++ = __PKHBT(out1, out2, 16);
      *__SIMD32(pCmplxDst)++ = __PKHBT(out3, out4, 16);
  
      inA1 = *__SIMD32(pSrcCmplx)++;
      inB1 = *__SIMD32(pSrcReal)++;
      inA2 = *__SIMD32(pSrcCmplx)++;
  
  #ifndef ARM_MATH_BIG_ENDIAN
  
      mul1 = (q31_t) ((q15_t) (inA1) * (q15_t) (inB1));
      mul2 = (q31_t) ((q15_t) (inA1 >> 16) * (q15_t) (inB1));
      mul3 = (q31_t) ((q15_t) (inA2) * (q15_t) (inB1 >> 16));
      mul4 = (q31_t) ((q15_t) (inA2 >> 16) * (q15_t) (inB1 >> 16));
  
  #else
  
      mul2 = (q31_t) ((q15_t) (inA1 >> 16) * (q15_t) (inB1 >> 16));
      mul1 = (q31_t) ((q15_t) inA1 * (q15_t) (inB1 >> 16));
      mul4 = (q31_t) ((q15_t) (inA2 >> 16) * (q15_t) inB1);
      mul3 = (q31_t) ((q15_t) inA2 * (q15_t) inB1);
  
  #endif /* #ifndef ARM_MATH_BIG_ENDIAN */
  
      out1 = (q15_t) __SSAT(mul1 >> 15u, 16);
      out2 = (q15_t) __SSAT(mul2 >> 15u, 16);
      out3 = (q15_t) __SSAT(mul3 >> 15u, 16);
      out4 = (q15_t) __SSAT(mul4 >> 15u, 16);
  
      *__SIMD32(pCmplxDst)++ = __PKHBT(out1, out2, 16);
      *__SIMD32(pCmplxDst)++ = __PKHBT(out3, out4, 16);
  
      /* 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;
  
    while (blkCnt > 0u)
    {
      /* C[2 * i] = A[2 * i] * B[i].            */
      /* C[2 * i + 1] = A[2 * i + 1] * B[i].        */
      in = *pSrcReal++;
      /* store the result in the destination buffer. */
      *pCmplxDst++ =
        (q15_t) __SSAT((((q31_t) (*pSrcCmplx++) * (in)) >> 15), 16);
      *pCmplxDst++ =
        (q15_t) __SSAT((((q31_t) (*pSrcCmplx++) * (in)) >> 15), 16);
  
      /* Decrement the numSamples loop counter */
      blkCnt--;
    }
  
  #else
  
    /* Run the below code for Cortex-M0 */
  
    while (numSamples > 0u)
    {
      /* realOut = realA * realB.            */
      /* imagOut = imagA * realB.                */
      in = *pSrcReal++;
      /* store the result in the destination buffer. */
      *pCmplxDst++ =
        (q15_t) __SSAT((((q31_t) (*pSrcCmplx++) * (in)) >> 15), 16);
      *pCmplxDst++ =
        (q15_t) __SSAT((((q31_t) (*pSrcCmplx++) * (in)) >> 15), 16);
  
      /* Decrement the numSamples loop counter */
      numSamples--;
    }
  
  #endif /* #if defined (ARM_MATH_DSP) */
  
  }
  
  /**
   * @} end of CmplxByRealMult group
   */
  