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  1. /* ----------------------------------------------------------------------    
  2. * Copyright (C) 2010-2014 ARM Limited. All rights reserved.    
  3. *    
  4. * $Date:        19. March 2015
  5. * $Revision:    V.1.4.5
  6. *    
  7. * Project:          CMSIS DSP Library    
  8. * Title:                arm_scale_f32.c    
  9. *    
  10. * Description:  Multiplies a floating-point vector by a scalar.    
  11. *    
  12. * Target Processor: Cortex-M4/Cortex-M3/Cortex-M0
  13. *  
  14. * Redistribution and use in source and binary forms, with or without
  15. * modification, are permitted provided that the following conditions
  16. * are met:
  17. *   - Redistributions of source code must retain the above copyright
  18. *     notice, this list of conditions and the following disclaimer.
  19. *   - Redistributions in binary form must reproduce the above copyright
  20. *     notice, this list of conditions and the following disclaimer in
  21. *     the documentation and/or other materials provided with the
  22. *     distribution.
  23. *   - Neither the name of ARM LIMITED nor the names of its contributors
  24. *     may be used to endorse or promote products derived from this
  25. *     software without specific prior written permission.
  26. *
  27. * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  28. * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  29. * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
  30. * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
  31. * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
  32. * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
  33. * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
  34. * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
  35. * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  36. * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
  37. * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  38. * POSSIBILITY OF SUCH DAMAGE.    
  39. * ---------------------------------------------------------------------------- */
  40.  
  41. #include "arm_math.h"
  42.  
  43. /**        
  44.  * @ingroup groupMath        
  45.  */
  46.  
  47. /**        
  48.  * @defgroup scale Vector Scale        
  49.  *        
  50.  * Multiply a vector by a scalar value.  For floating-point data, the algorithm used is:        
  51.  *        
  52.  * <pre>        
  53.  *     pDst[n] = pSrc[n] * scale,   0 <= n < blockSize.        
  54.  * </pre>        
  55.  *        
  56.  * In the fixed-point Q7, Q15, and Q31 functions, <code>scale</code> is represented by        
  57.  * a fractional multiplication <code>scaleFract</code> and an arithmetic shift <code>shift</code>.        
  58.  * The shift allows the gain of the scaling operation to exceed 1.0.        
  59.  * The algorithm used with fixed-point data is:        
  60.  *        
  61.  * <pre>        
  62.  *     pDst[n] = (pSrc[n] * scaleFract) << shift,   0 <= n < blockSize.        
  63.  * </pre>        
  64.  *        
  65.  * The overall scale factor applied to the fixed-point data is        
  66.  * <pre>        
  67.  *     scale = scaleFract * 2^shift.        
  68.  * </pre>        
  69.  *
  70.  * The functions support in-place computation allowing the source and destination
  71.  * pointers to reference the same memory buffer.
  72.  */
  73.  
  74. /**        
  75.  * @addtogroup scale        
  76.  * @{        
  77.  */
  78.  
  79. /**        
  80.  * @brief Multiplies a floating-point vector by a scalar.        
  81.  * @param[in]       *pSrc points to the input vector        
  82.  * @param[in]       scale scale factor to be applied        
  83.  * @param[out]      *pDst points to the output vector        
  84.  * @param[in]       blockSize number of samples in the vector        
  85.  * @return none.        
  86.  */
  87.  
  88.  
  89. void arm_scale_f32(
  90.   float32_t * pSrc,
  91.   float32_t scale,
  92.   float32_t * pDst,
  93.   uint32_t blockSize)
  94. {
  95.   uint32_t blkCnt;                               /* loop counter */
  96. #ifndef ARM_MATH_CM0_FAMILY
  97.  
  98. /* Run the below code for Cortex-M4 and Cortex-M3 */
  99.   float32_t in1, in2, in3, in4;                  /* temporary variabels */
  100.  
  101.   /*loop Unrolling */
  102.   blkCnt = blockSize >> 2u;
  103.  
  104.   /* First part of the processing with loop unrolling.  Compute 4 outputs at a time.        
  105.    ** a second loop below computes the remaining 1 to 3 samples. */
  106.   while(blkCnt > 0u)
  107.   {
  108.     /* C = A * scale */
  109.     /* Scale the input and then store the results in the destination buffer. */
  110.     /* read input samples from source */
  111.     in1 = *pSrc;
  112.     in2 = *(pSrc + 1);
  113.  
  114.     /* multiply with scaling factor */
  115.     in1 = in1 * scale;
  116.  
  117.     /* read input sample from source */
  118.     in3 = *(pSrc + 2);
  119.  
  120.     /* multiply with scaling factor */
  121.     in2 = in2 * scale;
  122.  
  123.     /* read input sample from source */
  124.     in4 = *(pSrc + 3);
  125.  
  126.     /* multiply with scaling factor */
  127.     in3 = in3 * scale;
  128.     in4 = in4 * scale;
  129.     /* store the result to destination */
  130.     *pDst = in1;
  131.     *(pDst + 1) = in2;
  132.     *(pDst + 2) = in3;
  133.     *(pDst + 3) = in4;
  134.  
  135.     /* update pointers to process next samples */
  136.     pSrc += 4u;
  137.     pDst += 4u;
  138.  
  139.     /* Decrement the loop counter */
  140.     blkCnt--;
  141.   }
  142.  
  143.   /* If the blockSize is not a multiple of 4, compute any remaining output samples here.        
  144.    ** No loop unrolling is used. */
  145.   blkCnt = blockSize % 0x4u;
  146.  
  147. #else
  148.  
  149.   /* Run the below code for Cortex-M0 */
  150.  
  151.   /* Initialize blkCnt with number of samples */
  152.   blkCnt = blockSize;
  153.  
  154. #endif /* #ifndef ARM_MATH_CM0_FAMILY */
  155.  
  156.   while(blkCnt > 0u)
  157.   {
  158.     /* C = A * scale */
  159.     /* Scale the input and then store the result in the destination buffer. */
  160.     *pDst++ = (*pSrc++) * scale;
  161.  
  162.     /* Decrement the loop counter */
  163.     blkCnt--;
  164.   }
  165. }
  166.  
  167. /**        
  168.  * @} end of scale group        
  169.  */
  170.