CMSIS-DSP/Source/SupportFunctions/arm_f16_to_q15.c

/* ----------------------------------------------------------------------
 * Project:      CMSIS DSP Library
 * Title:        arm_float_to_q15.c
 * Description:  Converts the elements of the floating-point vector to Q15 vector
 *
 * $Date:        23 April 2021
 * $Revision:    V1.9.0
 *
 * Target Processor: Cortex-M and Cortex-A cores
 * -------------------------------------------------------------------- */
/*
 * Copyright (C) 2010-2021 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/support_functions_f16.h"

#if defined(ARM_FLOAT16_SUPPORTED)


/**
  @ingroup groupSupport
 */

/**
  @addtogroup f16_to_x
  @{
 */

/**
  @brief         Converts the elements of the f16 vector to Q15 vector.
  @param[in]     pSrc       points to the f16 input vector
  @param[out]    pDst       points to the Q15 output vector
  @param[in]     blockSize  number of samples in each vector

  @par           Details
                   The equation used for the conversion process is:
  <pre>
      pDst[n] = (q15_t)(pSrc[n] * 32768);   0 <= n < blockSize.
  </pre>

  @par           Scaling and Overflow Behavior
                   The function uses saturating arithmetic.
                   Results outside of the allowable Q15 range [0x8000 0x7FFF] are saturated.

  @note
                   In order to apply rounding in scalar version, the library should be rebuilt with the ROUNDING macro
                   defined in the preprocessor section of project options.
 */

#if defined(ARM_MATH_MVE_FLOAT16) && !defined(ARM_MATH_AUTOVECTORIZE)

void arm_f16_to_q15(
  const float16_t * pSrc,
  q15_t * pDst,
  uint32_t blockSize)
{
    float16_t       maxQ = (float16_t) Q15_MAX;
    float16x8_t         vecDst;


    do {
        mve_pred16_t    p = vctp16q(blockSize);

        vecDst = vldrhq_z_f16((float16_t const *) pSrc, p);
        /* C = A * 32767 */
        /* convert from float to Q15 and then store the results in the destination buffer */
        vecDst = vmulq_m(vuninitializedq_f16(), vecDst, maxQ, p);

        vstrhq_p_s16(pDst,
            vcvtaq_m(vuninitializedq_s16(), vecDst, p), p);
        /*
         * Decrement the blockSize loop counter
         * Advance vector source and destination pointers
         */
        pSrc += 8;
        pDst += 8;
        blockSize -= 8;
    }
    while ((int32_t) blockSize > 0);
}

#else

void arm_f16_to_q15(
  const float16_t * pSrc,
        q15_t * pDst,
        uint32_t blockSize)
{
    const float16_t *pIn = pSrc;      /* Src pointer */
    uint32_t  blkCnt;           /* loop counter */
#ifdef ARM_MATH_ROUNDING
    float16_t in;
#endif                          /*      #ifdef ARM_MATH_ROUNDING        */

    /*
     * Loop over blockSize number of values
     */
    blkCnt = blockSize;

    while (blkCnt > 0U)
    {

#ifdef ARM_MATH_ROUNDING

        /*
         * C = A * 65536
         */
        /*
         * convert from float to Q31 and then store the results in the destination buffer
         */
        in = *pIn++;
        in = ((_Float16)in * (_Float16)32768.0f16);
        in += (_Float16)in > 0.0f16 ? 0.5f16 : -0.5f16;
        *pDst++ = clip_q31_to_q15((q31_t) (in));

#else

        /*
         * C = A * 32768
         */
        /*
         * convert from float to Q31 and then store the results in the destination buffer
         */
        *pDst++ = clip_q31_to_q15((q31_t) ((_Float16)*pIn++ * 32768.0f16));

#endif                          /*      #ifdef ARM_MATH_ROUNDING        */

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

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

/**
  @} end of f16_to_x group
 */

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