150 lines
3.9 KiB
C
150 lines
3.9 KiB
C
/* ----------------------------------------------------------------------
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* Project: CMSIS DSP Library
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* Title: arm_float_to_q7.c
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* Description: Converts the elements of the floating-point vector to Q7 vector
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*
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* $Date: 18. March 2019
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* $Revision: V1.6.0
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*
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* Target Processor: Cortex-M cores
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* -------------------------------------------------------------------- */
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/*
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* Copyright (C) 2010-2019 ARM Limited or its affiliates. All rights reserved.
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*
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* SPDX-License-Identifier: Apache-2.0
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*
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* Licensed under the Apache License, Version 2.0 (the License); you may
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* not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an AS IS BASIS, WITHOUT
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* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#include "arm_math.h"
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/**
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@ingroup groupSupport
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*/
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/**
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@addtogroup float_to_x
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@{
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*/
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/**
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@brief Converts the elements of the floating-point vector to Q7 vector.
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@param[in] pSrc points to the floating-point input vector
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@param[out] pDst points to the Q7 output vector
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@param[in] blockSize number of samples in each vector
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@return none
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@par Details
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The equation used for the conversion process is:
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<pre>
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pDst[n] = (q7_t)(pSrc[n] * 128); 0 <= n < blockSize.
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</pre>
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@par Scaling and Overflow Behavior
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The function uses saturating arithmetic.
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Results outside of the allowable Q7 range [0x80 0x7F] are saturated.
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@note
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In order to apply rounding, the library should be rebuilt with the ROUNDING macro
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defined in the preprocessor section of project options.
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*/
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void arm_float_to_q7(
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const float32_t * pSrc,
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q7_t * pDst,
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uint32_t blockSize)
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{
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uint32_t blkCnt; /* Loop counter */
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const float32_t *pIn = pSrc; /* Source pointer */
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#ifdef ARM_MATH_ROUNDING
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float32_t in;
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#endif /* #ifdef ARM_MATH_ROUNDING */
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#if defined (ARM_MATH_LOOPUNROLL)
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/* Loop unrolling: Compute 4 outputs at a time */
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blkCnt = blockSize >> 2U;
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while (blkCnt > 0U)
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{
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/* C = A * 128 */
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/* Convert from float to q7 and store result in destination buffer */
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#ifdef ARM_MATH_ROUNDING
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in = (*pIn++ * 128);
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in += in > 0.0f ? 0.5f : -0.5f;
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*pDst++ = (q7_t) (__SSAT((q15_t) (in), 8));
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in = (*pIn++ * 128);
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in += in > 0.0f ? 0.5f : -0.5f;
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*pDst++ = (q7_t) (__SSAT((q15_t) (in), 8));
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in = (*pIn++ * 128);
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in += in > 0.0f ? 0.5f : -0.5f;
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*pDst++ = (q7_t) (__SSAT((q15_t) (in), 8));
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in = (*pIn++ * 128);
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in += in > 0.0f ? 0.5f : -0.5f;
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*pDst++ = (q7_t) (__SSAT((q15_t) (in), 8));
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#else
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*pDst++ = __SSAT((q31_t) (*pIn++ * 128.0f), 8);
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*pDst++ = __SSAT((q31_t) (*pIn++ * 128.0f), 8);
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*pDst++ = __SSAT((q31_t) (*pIn++ * 128.0f), 8);
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*pDst++ = __SSAT((q31_t) (*pIn++ * 128.0f), 8);
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#endif /* #ifdef ARM_MATH_ROUNDING */
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/* Decrement loop counter */
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blkCnt--;
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}
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/* Loop unrolling: Compute remaining outputs */
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blkCnt = blockSize % 0x4U;
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#else
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/* Initialize blkCnt with number of samples */
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blkCnt = blockSize;
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#endif /* #if defined (ARM_MATH_LOOPUNROLL) */
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while (blkCnt > 0U)
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{
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/* C = A * 128 */
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/* Convert from float to q7 and store result in destination buffer */
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#ifdef ARM_MATH_ROUNDING
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in = (*pIn++ * 128);
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in += in > 0.0f ? 0.5f : -0.5f;
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*pDst++ = (q7_t) (__SSAT((q15_t) (in), 8));
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#else
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*pDst++ = (q7_t) __SSAT((q31_t) (*pIn++ * 128.0f), 8);
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#endif /* #ifdef ARM_MATH_ROUNDING */
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/* Decrement loop counter */
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blkCnt--;
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}
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}
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/**
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@} end of float_to_x group
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*/
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