arm_float_to_q15.c
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| 4.2 KiB
| text/x-c
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CLexer
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r16 | /* ---------------------------------------------------------------------------- | ||
* Copyright (C) 2010 ARM Limited. All rights reserved. | ||||
* | ||||
* $Date: 29. November 2010 | ||||
* $Revision: V1.0.3 | ||||
* | ||||
* Project: CMSIS DSP Library | ||||
* Title: arm_float_to_q15.c | ||||
* | ||||
* Description: Processing function for the Conversion from float to Q15 | ||||
* | ||||
* Target Processor: Cortex-M4/Cortex-M3 | ||||
* | ||||
* Version 1.0.3 2010/11/29 | ||||
* Re-organized the CMSIS folders and updated documentation. | ||||
* | ||||
* Version 1.0.2 2010/11/11 | ||||
* Documentation updated. | ||||
* | ||||
* Version 1.0.1 2010/10/05 | ||||
* Production release and review comments incorporated. | ||||
* | ||||
* Version 1.0.0 2010/09/20 | ||||
* Production release and review comments incorporated. | ||||
* ---------------------------------------------------------------------------- */ | ||||
#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 length of the input vector | ||||
* @return none. | ||||
* | ||||
* \par Description: | ||||
* \par | ||||
* 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: | ||||
* \par | ||||
* The function uses saturating arithmetic. | ||||
* Results outside of the allowable Q15 range [0x8000 0x7FFF] will be saturated. | ||||
* \note | ||||
* In order to apply rounding, the library should be rebuilt with the ROUNDING macro | ||||
* defined in the preprocessor section of project options. | ||||
* | ||||
*/ | ||||
void arm_float_to_q15( | ||||
float32_t * pSrc, | ||||
q15_t * pDst, | ||||
uint32_t blockSize) | ||||
{ | ||||
float32_t *pIn = pSrc; /* Src pointer */ | ||||
uint32_t blkCnt; /* loop counter */ | ||||
#ifdef ARM_MATH_ROUNDING | ||||
float32_t in; | ||||
#endif | ||||
/*loop Unrolling */ | ||||
blkCnt = blockSize >> 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) | ||||
{ | ||||
#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 ? 0.5 : -0.5; | ||||
*pDst++ = (q15_t) (__SSAT((q31_t) (in), 16)); | ||||
in = *pIn++; | ||||
in = (in * 32768.0f); | ||||
in += in > 0 ? 0.5 : -0.5; | ||||
*pDst++ = (q15_t) (__SSAT((q31_t) (in), 16)); | ||||
in = *pIn++; | ||||
in = (in * 32768.0f); | ||||
in += in > 0 ? 0.5 : -0.5; | ||||
*pDst++ = (q15_t) (__SSAT((q31_t) (in), 16)); | ||||
in = *pIn++; | ||||
in = (in * 32768.0f); | ||||
in += in > 0 ? 0.5 : -0.5; | ||||
*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); | ||||
*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 | ||||
/* 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 % 0x4u; | ||||
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 * 32768LL); | ||||
in += in > 0 ? 0.5 : -0.5; | ||||
*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 | ||||
/* Decrement the loop counter */ | ||||
blkCnt--; | ||||
} | ||||
} | ||||
/** | ||||
* @} end of float_to_x group | ||||
*/ | ||||