arm_scale_f32.c

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_scale_f32.c  
00009 *  
00010 * Description:  Multiplies a floating-point vector by a scalar.  
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 * Version 0.0.7  2010/06/10   
00027 *    Misra-C changes done  
00028 * ---------------------------------------------------------------------------- */ 
00029  
00030 #include "arm_math.h" 
00031  
00032 /**  
00033  * @ingroup groupMath  
00034  */ 
00035  
00036 /**  
00037  * @defgroup scale Vector Scale  
00038  *  
00039  * Multiply a vector by a scalar value.  For floating-point data, the algorithm used is:  
00040  *  
00041  * <pre>  
00042  *     pDst[n] = pSrc[n] * scale,   0 <= n < blockSize.  
00043  * </pre>  
00044  *  
00045  * In the fixed-point Q7, Q15, and Q31 functions, <code>scale</code> is represented by  
00046  * a fractional multiplication <code>scaleFract</code> and an arithmetic shift <code>shift</code>.  
00047  * The shift allows the gain of the scaling operation to exceed 1.0.  
00048  * The algorithm used with fixed-point data is:  
00049  *  
00050  * <pre>  
00051  *     pDst[n] = (pSrc[n] * scaleFract) << shift,   0 <= n < blockSize.  
00052  * </pre>  
00053  *  
00054  * The overall scale factor applied to the fixed-point data is  
00055  * <pre>  
00056  *     scale = scaleFract * 2^shift.  
00057  * </pre>  
00058  */ 
00059  
00060 /**  
00061  * @addtogroup scale  
00062  * @{  
00063  */ 
00064  
00065 /**  
00066  * @brief Multiplies a floating-point vector by a scalar.  
00067  * @param[in]       *pSrc points to the input vector  
00068  * @param[in]       scale scale factor to be applied  
00069  * @param[out]      *pDst points to the output vector  
00070  * @param[in]       blockSize number of samples in the vector  
00071  * @return none.  
00072  */ 
00073  
00074  
00075 void arm_scale_f32( 
00076   float32_t * pSrc, 
00077   float32_t scale, 
00078   float32_t * pDst, 
00079   uint32_t blockSize) 
00080 { 
00081   uint32_t blkCnt;                               /* loop counter */ 
00082  
00083   /*loop Unrolling */ 
00084   blkCnt = blockSize >> 2u; 
00085  
00086   /* First part of the processing with loop unrolling.  Compute 4 outputs at a time.  
00087    ** a second loop below computes the remaining 1 to 3 samples. */ 
00088   while(blkCnt > 0u) 
00089   { 
00090     /* C = A * scale */ 
00091     /* Scale the input and then store the results in the destination buffer. */ 
00092     *pDst++ = (*pSrc++) * scale; 
00093     *pDst++ = (*pSrc++) * scale; 
00094     *pDst++ = (*pSrc++) * scale; 
00095     *pDst++ = (*pSrc++) * scale; 
00096  
00097     /* Decrement the loop counter */ 
00098     blkCnt--; 
00099   } 
00100  
00101   /* If the blockSize is not a multiple of 4, compute any remaining output samples here.  
00102    ** No loop unrolling is used. */ 
00103   blkCnt = blockSize % 0x4u; 
00104  
00105   while(blkCnt > 0u) 
00106   { 
00107     /* C = A * scale */ 
00108     /* Scale the input and then store the result in the destination buffer. */ 
00109     *pDst++ = (*pSrc++) * scale; 
00110  
00111     /* Decrement the loop counter */ 
00112     blkCnt--; 
00113   } 
00114 } 
00115  
00116 /**  
00117  * @} end of scale group  
00118  */