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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_power_q15.c    
  9. *    
  10. * Description:  Sum of the squares of the elements of a Q15 vector.    
  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 groupStats    
  45.  */
  46.  
  47. /**    
  48.  * @addtogroup power    
  49.  * @{    
  50.  */
  51.  
  52. /**    
  53.  * @brief Sum of the squares of the elements of a Q15 vector.    
  54.  * @param[in]       *pSrc points to the input vector    
  55.  * @param[in]       blockSize length of the input vector    
  56.  * @param[out]      *pResult sum of the squares value returned here    
  57.  * @return none.    
  58.  *    
  59.  * @details    
  60.  * <b>Scaling and Overflow Behavior:</b>    
  61.  *    
  62.  * \par    
  63.  * The function is implemented using a 64-bit internal accumulator.    
  64.  * The input is represented in 1.15 format.  
  65.  * Intermediate multiplication yields a 2.30 format, and this    
  66.  * result is added without saturation to a 64-bit accumulator in 34.30 format.    
  67.  * With 33 guard bits in the accumulator, there is no risk of overflow, and the    
  68.  * full precision of the intermediate multiplication is preserved.    
  69.  * Finally, the return result is in 34.30 format.    
  70.  *    
  71.  */
  72.  
  73. void arm_power_q15(
  74.   q15_t * pSrc,
  75.   uint32_t blockSize,
  76.   q63_t * pResult)
  77. {
  78.   q63_t sum = 0;                                 /* Temporary result storage */
  79.  
  80. #ifndef ARM_MATH_CM0_FAMILY
  81.  
  82.   /* Run the below code for Cortex-M4 and Cortex-M3 */
  83.  
  84.   q31_t in32;                                    /* Temporary variable to store input value */
  85.   q15_t in16;                                    /* Temporary variable to store input value */
  86.   uint32_t blkCnt;                               /* loop counter */
  87.  
  88.  
  89.   /* loop Unrolling */
  90.   blkCnt = blockSize >> 2u;
  91.  
  92.   /* First part of the processing with loop unrolling.  Compute 4 outputs at a time.    
  93.    ** a second loop below computes the remaining 1 to 3 samples. */
  94.   while(blkCnt > 0u)
  95.   {
  96.     /* C = A[0] * A[0] + A[1] * A[1] + A[2] * A[2] + ... + A[blockSize-1] * A[blockSize-1] */
  97.     /* Compute Power and then store the result in a temporary variable, sum. */
  98.     in32 = *__SIMD32(pSrc)++;
  99.     sum = __SMLALD(in32, in32, sum);
  100.     in32 = *__SIMD32(pSrc)++;
  101.     sum = __SMLALD(in32, in32, sum);
  102.  
  103.     /* Decrement the loop counter */
  104.     blkCnt--;
  105.   }
  106.  
  107.   /* If the blockSize is not a multiple of 4, compute any remaining output samples here.    
  108.    ** No loop unrolling is used. */
  109.   blkCnt = blockSize % 0x4u;
  110.  
  111.   while(blkCnt > 0u)
  112.   {
  113.     /* C = A[0] * A[0] + A[1] * A[1] + A[2] * A[2] + ... + A[blockSize-1] * A[blockSize-1] */
  114.     /* Compute Power and then store the result in a temporary variable, sum. */
  115.     in16 = *pSrc++;
  116.     sum = __SMLALD(in16, in16, sum);
  117.  
  118.     /* Decrement the loop counter */
  119.     blkCnt--;
  120.   }
  121.  
  122. #else
  123.  
  124.   /* Run the below code for Cortex-M0 */
  125.  
  126.   q15_t in;                                      /* Temporary variable to store input value */
  127.   uint32_t blkCnt;                               /* loop counter */
  128.  
  129.  
  130.   /* Loop over blockSize number of values */
  131.   blkCnt = blockSize;
  132.  
  133.   while(blkCnt > 0u)
  134.   {
  135.     /* C = A[0] * A[0] + A[1] * A[1] + A[2] * A[2] + ... + A[blockSize-1] * A[blockSize-1] */
  136.     /* Compute Power and then store the result in a temporary variable, sum. */
  137.     in = *pSrc++;
  138.     sum += ((q31_t) in * in);
  139.  
  140.     /* Decrement the loop counter */
  141.     blkCnt--;
  142.   }
  143.  
  144. #endif /* #ifndef ARM_MATH_CM0_FAMILY */
  145.  
  146.   /* Store the results in 34.30 format  */
  147.   *pResult = sum;
  148. }
  149.  
  150. /**    
  151.  * @} end of power group    
  152.  */
  153.