arm_float_to_q31.c

00001 /* ----------------------------------------------------------------------------    
00002 * Copyright (C) 2010-2014 ARM Limited. All rights reserved.    
00003 *    
00004 * $Date:        12. March 2014 
00005 * $Revision:    V1.4.3  
00006 *    
00007 * Project:      CMSIS DSP Library    
00008 * Title:        arm_float_to_q31.c    
00009 *    
00010 * Description:  Converts the elements of the floating-point vector to Q31 vector.    
00011 *    
00012 * Target Processor: Cortex-M4/Cortex-M3/Cortex-M0
00013 *  
00014 * Redistribution and use in source and binary forms, with or without 
00015 * modification, are permitted provided that the following conditions
00016 * are met:
00017 *   - Redistributions of source code must retain the above copyright
00018 *     notice, this list of conditions and the following disclaimer.
00019 *   - Redistributions in binary form must reproduce the above copyright
00020 *     notice, this list of conditions and the following disclaimer in
00021 *     the documentation and/or other materials provided with the 
00022 *     distribution.
00023 *   - Neither the name of ARM LIMITED nor the names of its contributors
00024 *     may be used to endorse or promote products derived from this
00025 *     software without specific prior written permission.
00026 *
00027 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
00028 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
00029 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
00030 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE 
00031 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
00032 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
00033 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
00034 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
00035 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
00036 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
00037 * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
00038 * POSSIBILITY OF SUCH DAMAGE.  
00039 * ---------------------------------------------------------------------------- */
00040 
00041 #include "arm_math.h"
00042 
00043 /**    
00044  * @ingroup groupSupport    
00045  */
00046 
00047 /**    
00048  * @defgroup float_to_x  Convert 32-bit floating point value    
00049  */
00050 
00051 /**    
00052  * @addtogroup float_to_x    
00053  * @{    
00054  */
00055 
00056 /**    
00057  * @brief Converts the elements of the floating-point vector to Q31 vector.    
00058  * @param[in]       *pSrc points to the floating-point input vector    
00059  * @param[out]      *pDst points to the Q31 output vector   
00060  * @param[in]       blockSize length of the input vector    
00061  * @return none.    
00062  *    
00063  *\par Description:    
00064  * \par   
00065  * The equation used for the conversion process is:    
00066  *   
00067  * <pre>    
00068  *  pDst[n] = (q31_t)(pSrc[n] * 2147483648);   0 <= n < blockSize.    
00069  * </pre>    
00070  * <b>Scaling and Overflow Behavior:</b>    
00071  * \par    
00072  * The function uses saturating arithmetic.    
00073  * Results outside of the allowable Q31 range[0x80000000 0x7FFFFFFF] will be saturated.    
00074  *   
00075  * \note In order to apply rounding, the library should be rebuilt with the ROUNDING macro     
00076  * defined in the preprocessor section of project options.     
00077  */
00078 
00079 
00080 void arm_float_to_q31(
00081   float32_t * pSrc,
00082   q31_t * pDst,
00083   uint32_t blockSize)
00084 {
00085   float32_t *pIn = pSrc;                         /* Src pointer */
00086   uint32_t blkCnt;                               /* loop counter */
00087 
00088 #ifdef ARM_MATH_ROUNDING
00089 
00090   float32_t in;
00091 
00092 #endif /*      #ifdef ARM_MATH_ROUNDING        */
00093 
00094 #ifndef ARM_MATH_CM0_FAMILY
00095 
00096   /* Run the below code for Cortex-M4 and Cortex-M3 */
00097 
00098   /*loop Unrolling */
00099   blkCnt = blockSize >> 2u;
00100 
00101   /* First part of the processing with loop unrolling.  Compute 4 outputs at a time.    
00102    ** a second loop below computes the remaining 1 to 3 samples. */
00103   while(blkCnt > 0u)
00104   {
00105 
00106 #ifdef ARM_MATH_ROUNDING
00107 
00108     /* C = A * 32768 */
00109     /* convert from float to Q31 and then store the results in the destination buffer */
00110     in = *pIn++;
00111     in = (in * 2147483648.0f);
00112     in += in > 0 ? 0.5 : -0.5;
00113     *pDst++ = clip_q63_to_q31((q63_t) (in));
00114 
00115     in = *pIn++;
00116     in = (in * 2147483648.0f);
00117     in += in > 0 ? 0.5 : -0.5;
00118     *pDst++ = clip_q63_to_q31((q63_t) (in));
00119 
00120     in = *pIn++;
00121     in = (in * 2147483648.0f);
00122     in += in > 0 ? 0.5 : -0.5;
00123     *pDst++ = clip_q63_to_q31((q63_t) (in));
00124 
00125     in = *pIn++;
00126     in = (in * 2147483648.0f);
00127     in += in > 0 ? 0.5 : -0.5;
00128     *pDst++ = clip_q63_to_q31((q63_t) (in));
00129 
00130 #else
00131 
00132     /* C = A * 2147483648 */
00133     /* convert from float to Q31 and then store the results in the destination buffer */
00134     *pDst++ = clip_q63_to_q31((q63_t) (*pIn++ * 2147483648.0f));
00135     *pDst++ = clip_q63_to_q31((q63_t) (*pIn++ * 2147483648.0f));
00136     *pDst++ = clip_q63_to_q31((q63_t) (*pIn++ * 2147483648.0f));
00137     *pDst++ = clip_q63_to_q31((q63_t) (*pIn++ * 2147483648.0f));
00138 
00139 #endif /*      #ifdef ARM_MATH_ROUNDING        */
00140 
00141     /* Decrement the loop counter */
00142     blkCnt--;
00143   }
00144 
00145   /* If the blockSize is not a multiple of 4, compute any remaining output samples here.    
00146    ** No loop unrolling is used. */
00147   blkCnt = blockSize % 0x4u;
00148 
00149   while(blkCnt > 0u)
00150   {
00151 
00152 #ifdef ARM_MATH_ROUNDING
00153 
00154     /* C = A * 2147483648 */
00155     /* convert from float to Q31 and then store the results in the destination buffer */
00156     in = *pIn++;
00157     in = (in * 2147483648.0f);
00158     in += in > 0 ? 0.5 : -0.5;
00159     *pDst++ = clip_q63_to_q31((q63_t) (in));
00160 
00161 #else
00162 
00163     /* C = A * 2147483648 */
00164     /* convert from float to Q31 and then store the results in the destination buffer */
00165     *pDst++ = clip_q63_to_q31((q63_t) (*pIn++ * 2147483648.0f));
00166 
00167 #endif /*      #ifdef ARM_MATH_ROUNDING        */
00168 
00169     /* Decrement the loop counter */
00170     blkCnt--;
00171   }
00172 
00173 
00174 #else
00175 
00176   /* Run the below code for Cortex-M0 */
00177 
00178   /* Loop over blockSize number of values */
00179   blkCnt = blockSize;
00180 
00181   while(blkCnt > 0u)
00182   {
00183 
00184 #ifdef ARM_MATH_ROUNDING
00185 
00186     /* C = A * 2147483648 */
00187     /* convert from float to Q31 and then store the results in the destination buffer */
00188     in = *pIn++;
00189     in = (in * 2147483648.0f);
00190     in += in > 0 ? 0.5f : -0.5f;
00191     *pDst++ = clip_q63_to_q31((q63_t) (in));
00192 
00193 #else
00194 
00195     /* C = A * 2147483648 */
00196     /* convert from float to Q31 and then store the results in the destination buffer */
00197     *pDst++ = clip_q63_to_q31((q63_t) (*pIn++ * 2147483648.0f));
00198 
00199 #endif /*      #ifdef ARM_MATH_ROUNDING        */
00200 
00201     /* Decrement the loop counter */
00202     blkCnt--;
00203   }
00204 
00205 #endif /* #ifndef ARM_MATH_CM0_FAMILY */
00206 
00207 }
00208 
00209 /**    
00210  * @} end of float_to_x group    
00211  */