/* ---------------------------------------------------------------------------- * Copyright (C) 2010 ARM Limited. All rights reserved. * * $Date: 15. February 2012 * $Revision: V1.1.0 * * Project: CMSIS DSP Library * Title: arm_float_to_q15.c * * Description: Converts the elements of the floating-point vector to Q15 vector. * * Target Processor: Cortex-M4/Cortex-M3/Cortex-M0 * * Version 1.1.0 2012/02/15 * Updated with more optimizations, bug fixes and minor API changes. * * Version 1.0.10 2011/7/15 * Big Endian support added and Merged M0 and M3/M4 Source code. * * 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: *
* pDst[n] = (q15_t)(pSrc[n] * 32768); 0 <= n < blockSize. ** \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 /* #ifdef ARM_MATH_ROUNDING */ #ifndef ARM_MATH_CM0 /* Run the below code for Cortex-M4 and Cortex-M3 */ /*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 /* #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 % 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 * 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); #endif /* #ifdef ARM_MATH_ROUNDING */ /* Decrement the loop counter */ blkCnt--; } #else /* Run the below code for Cortex-M0 */ /* Loop over blockSize number of values */ blkCnt = blockSize; 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 ? 0.5f : -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--; } #endif /* #ifndef ARM_MATH_CM0 */ } /** * @} end of float_to_x group */