/* ----------------------------------------------------------------------
* Project: CMSIS DSP Library
* Title: arm_float_to_q15.c
* Description: Converts the elements of the floating-point vector to Q15 vector
*
* $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 "arm_math.h"
/**
@ingroup groupSupport
*/
/**
@addtogroup float_to_x
@{
*/
/**
@brief Converts the elements of the floating-point vector to Q15 vector.
@param[in] pSrc points to the floating-point input vector
@param[out] pDst points to the Q15 output vector
@param[in] blockSize number of samples in each vector
@return none
@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, the library should be rebuilt with the ROUNDING macro
defined in the preprocessor section of project options.
*/
#if defined(ARM_MATH_NEON_EXPERIMENTAL)
void arm_float_to_q15(
const float32_t * pSrc,
q15_t * pDst,
uint32_t blockSize)
{
const float32_t *pIn = pSrc; /* Src pointer */
uint32_t blkCnt; /* loop counter */
float32_t in;
float32x4_t inV;
#ifdef ARM_MATH_ROUNDING
float32x4_t zeroV = vdupq_n_f32(0.0f);
float32x4_t pHalf = vdupq_n_f32(0.5f / 32768.0f);
float32x4_t mHalf = vdupq_n_f32(-0.5f / 32768.0f);
float32x4_t r;
uint32x4_t cmp;
#endif
int32x4_t cvt;
int16x4_t outV;
blkCnt = blockSize >> 2U;
/* Compute 4 outputs at a time.
** a second loop below computes the remaining 1 to 3 samples. */
while (blkCnt > 0U)
{
#ifdef ARM_MATH_ROUNDING
/* C = A * 32768 */
/* Convert from float to q15 and then store the results in the destination buffer */
inV = vld1q_f32(pIn);
cmp = vcgtq_f32(inV,zeroV);
r = vbslq_f32(cmp,pHalf,mHalf);
inV = vaddq_f32(inV, r);
pIn += 4;
cvt = vcvtq_n_s32_f32(inV,15);
outV = vqmovn_s32(cvt);
vst1_s16(pDst, outV);
pDst += 4;
#else
/* C = A * 32768 */
/* Convert from float to q15 and then store the results in the destination buffer */
inV = vld1q_f32(pIn);
cvt = vcvtq_n_s32_f32(inV,15);
outV = vqmovn_s32(cvt);
vst1_s16(pDst, outV);
pDst += 4;
pIn += 4;
#endif /* #ifdef ARM_MATH_ROUNDING */
/* Decrement the loop counter */
blkCnt--;
}
/* If the blockSize is not a multiple of 4, compute any remaining output samples here.
** No loop unrolling is used. */
blkCnt = blockSize & 3;
while (blkCnt > 0U)
{
#ifdef ARM_MATH_ROUNDING
/* C = A * 32768 */
/* Convert from float to q15 and then store the results in the destination buffer */
in = *pIn++;
in = (in * 32768.0f);
in += in > 0.0f ? 0.5f : -0.5f;
*pDst++ = (q15_t) (__SSAT((q31_t) (in), 16));
#else
/* C = A * 32768 */
/* Convert from float to q15 and then store the results in the destination buffer */
*pDst++ = (q15_t) __SSAT((q31_t) (*pIn++ * 32768.0f), 16);
#endif /* #ifdef ARM_MATH_ROUNDING */
/* Decrement the loop counter */
blkCnt--;
}
}
#else
void arm_float_to_q15(
const float32_t * pSrc,
q15_t * pDst,
uint32_t blockSize)
{
uint32_t blkCnt; /* Loop counter */
const float32_t *pIn = pSrc; /* Source pointer */
#ifdef ARM_MATH_ROUNDING
float32_t in;
#endif /* #ifdef ARM_MATH_ROUNDING */
#if defined (ARM_MATH_LOOPUNROLL)
/* Loop unrolling: Compute 4 outputs at a time */
blkCnt = blockSize >> 2U;
while (blkCnt > 0U)
{
/* C = A * 32768 */
/* convert from float to Q15 and store result in destination buffer */
#ifdef ARM_MATH_ROUNDING
in = (*pIn++ * 32768.0f);
in += in > 0.0f ? 0.5f : -0.5f;
*pDst++ = (q15_t) (__SSAT((q31_t) (in), 16));
in = (*pIn++ * 32768.0f);
in += in > 0.0f ? 0.5f : -0.5f;
*pDst++ = (q15_t) (__SSAT((q31_t) (in), 16));
in = (*pIn++ * 32768.0f);
in += in > 0.0f ? 0.5f : -0.5f;
*pDst++ = (q15_t) (__SSAT((q31_t) (in), 16));
in = (*pIn++ * 32768.0f);
in += in > 0.0f ? 0.5f : -0.5f;
*pDst++ = (q15_t) (__SSAT((q31_t) (in), 16));
#else
*pDst++ = (q15_t) __SSAT((q31_t) (*pIn++ * 32768.0f), 16);
*pDst++ = (q15_t) __SSAT((q31_t) (*pIn++ * 32768.0f), 16);
*pDst++ = (q15_t) __SSAT((q31_t) (*pIn++ * 32768.0f), 16);
*pDst++ = (q15_t) __SSAT((q31_t) (*pIn++ * 32768.0f), 16);
#endif /* #ifdef ARM_MATH_ROUNDING */
/* Decrement loop counter */
blkCnt--;
}
/* Loop unrolling: Compute remaining outputs */
blkCnt = blockSize % 0x4U;
#else
/* Initialize blkCnt with number of samples */
blkCnt = blockSize;
#endif /* #if defined (ARM_MATH_LOOPUNROLL) */
while (blkCnt > 0U)
{
/* C = A * 32768 */
/* convert from float to Q15 and store result in destination buffer */
#ifdef ARM_MATH_ROUNDING
in = (*pIn++ * 32768.0f);
in += in > 0.0f ? 0.5f : -0.5f;
*pDst++ = (q15_t) (__SSAT((q31_t) (in), 16));
#else
/* C = A * 32768 */
/* Convert from float to q15 and then store the results in the destination buffer */
*pDst++ = (q15_t) __SSAT((q31_t) (*pIn++ * 32768.0f), 16);
#endif /* #ifdef ARM_MATH_ROUNDING */
/* Decrement loop counter */
blkCnt--;
}
}
#endif /* #if defined(ARM_MATH_NEON) */
/**
@} end of float_to_x group
*/
