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# arm_float_to_q15.c

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    00001 /* ----------------------------------------------------------------------------
    00002 * Copyright (C) 2010 ARM Limited. All rights reserved.
    00003 *
    00004 * $Date:        29. November 2010
    00005 * $Revision:    V1.0.3
    00006 *
    00007 * Project:      CMSIS DSP Library
    00008 * Title:        arm_float_to_q15.c
    00009 *
    00010 * Description:  Processing function for the Conversion from float to Q15
    00011 *
    00012 * Target Processor: Cortex-M4/Cortex-M3
    00013 *
    00014 * Version 1.0.3 2010/11/29
    00015 *    Re-organized the CMSIS folders and updated documentation.
    00016 *
    00017 * Version 1.0.2 2010/11/11
    00018 *    Documentation updated.
    00019 *
    00020 * Version 1.0.1 2010/10/05
    00021 *    Production release and review comments incorporated.
    00022 *
    00023 * Version 1.0.0 2010/09/20
    00024 *    Production release and review comments incorporated.
    00025 * ---------------------------------------------------------------------------- */
    00026
    00027 #include "arm_math.h"
    00028
    00062 void arm_float_to_q15(
    00063   float32_t * pSrc,
    00064   q15_t * pDst,
    00065   uint32_t blockSize)
    00066 {
    00067   float32_t *pIn = pSrc;                         /* Src pointer */
    00068   uint32_t blkCnt;                               /* loop counter */
    00069
    00070 #ifdef ARM_MATH_ROUNDING
    00071
    00072   float32_t in;
    00073
    00074 #endif
    00075
    00076   /*loop Unrolling */
    00077   blkCnt = blockSize >> 2u;
    00078
    00079   /* First part of the processing with loop unrolling.  Compute 4 outputs at a time.
    00080    ** a second loop below computes the remaining 1 to 3 samples. */
    00081   while(blkCnt > 0u)
    00082   {
    00083
    00084 #ifdef ARM_MATH_ROUNDING
    00085     /* C = A * 32768 */
    00086     /* convert from float to q15 and then store the results in the destination buffer */
    00087     in = *pIn++;
    00088     in = (in * 32768.0f);
    00089     in += in > 0 ? 0.5 : -0.5;
    00090     *pDst++ = (q15_t) (__SSAT((q31_t) (in), 16));
    00091
    00092     in = *pIn++;
    00093     in = (in * 32768.0f);
    00094     in += in > 0 ? 0.5 : -0.5;
    00095     *pDst++ = (q15_t) (__SSAT((q31_t) (in), 16));
    00096
    00097     in = *pIn++;
    00098     in = (in * 32768.0f);
    00099     in += in > 0 ? 0.5 : -0.5;
    00100     *pDst++ = (q15_t) (__SSAT((q31_t) (in), 16));
    00101
    00102     in = *pIn++;
    00103     in = (in * 32768.0f);
    00104     in += in > 0 ? 0.5 : -0.5;
    00105     *pDst++ = (q15_t) (__SSAT((q31_t) (in), 16));
    00106
    00107 #else
    00108
    00109     /* C = A * 32768 */
    00110     /* convert from float to q15 and then store the results in the destination buffer */
    00111     *pDst++ = (q15_t) __SSAT((q31_t) (*pIn++ * 32768.0f), 16);
    00112     *pDst++ = (q15_t) __SSAT((q31_t) (*pIn++ * 32768.0f), 16);
    00113     *pDst++ = (q15_t) __SSAT((q31_t) (*pIn++ * 32768.0f), 16);
    00114     *pDst++ = (q15_t) __SSAT((q31_t) (*pIn++ * 32768.0f), 16);
    00115
    00116 #endif
    00117
    00118     /* Decrement the loop counter */
    00119     blkCnt--;
    00120   }
    00121
    00122   /* If the blockSize is not a multiple of 4, compute any remaining output samples here.
    00123    ** No loop unrolling is used. */
    00124   blkCnt = blockSize % 0x4u;
    00125
    00126   while(blkCnt > 0u)
    00127   {
    00128
    00129 #ifdef ARM_MATH_ROUNDING
    00130     /* C = A * 32768 */
    00131     /* convert from float to q15 and then store the results in the destination buffer */
    00132     in = *pIn++;
    00133     in = (in * 32768LL);
    00134     in += in > 0 ? 0.5 : -0.5;
    00135     *pDst++ = (q15_t) (__SSAT((q31_t) (in), 16));
    00136
    00137 #else
    00138
    00139     /* C = A * 32768 */
    00140     /* convert from float to q15 and then store the results in the destination buffer */
    00141     *pDst++ = (q15_t) __SSAT((q31_t) (*pIn++ * 32768.0f), 16);
    00142
    00143 #endif
    00144
    00145     /* Decrement the loop counter */
    00146     blkCnt--;
    00147   }
    00148 }
    00149

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