arm_mat_scale_q31.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_mat_scale_q31.c  
00009 *  
00010 * Description:  Multiplies a Q31 matrix 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 0.0.5  2010/04/26   
00027 *    incorporated review comments and updated with latest CMSIS layer  
00028 *  
00029 * Version 0.0.3  2010/03/10   
00030 *    Initial version  
00031 * -------------------------------------------------------------------- */ 
00032  
00033 #include "arm_math.h" 
00034  
00035 /**  
00036  * @ingroup groupMatrix  
00037  */ 
00038  
00039 /**  
00040  * @addtogroup MatrixScale  
00041  * @{  
00042  */ 
00043  
00044 /**  
00045  * @brief Q31 matrix scaling.  
00046  * @param[in]       *pSrc points to input matrix  
00047  * @param[in]       scaleFract fractional portion of the scale factor  
00048  * @param[in]       shift number of bits to shift the result by  
00049  * @param[out]      *pDst points to output matrix structure  
00050  * @return          The function returns either  
00051  * <code>ARM_MATH_SIZE_MISMATCH</code> or <code>ARM_MATH_SUCCESS</code> based on the outcome of size checking.  
00052  *  
00053  * @details  
00054  * <b>Scaling and Overflow Behavior:</b>  
00055  * \par  
00056  * The input data <code>*pSrc</code> and <code>scaleFract</code> are in 1.31 format.  
00057  * These are multiplied to yield a 2.62 intermediate result and this is shifted with saturation to 1.31 format.  
00058  */ 
00059  
00060 arm_status arm_mat_scale_q31( 
00061   const arm_matrix_instance_q31 * pSrc, 
00062   q31_t scaleFract, 
00063   int32_t shift, 
00064   arm_matrix_instance_q31 * pDst) 
00065 { 
00066   q31_t *pIn = pSrc->pData;                      /* input data matrix pointer */ 
00067   q31_t *pOut = pDst->pData;                     /* output data matrix pointer */ 
00068   q63_t out;                                     /* temporary variable to hold output value */ 
00069   uint32_t numSamples;                           /* total number of elements in the matrix */ 
00070   int32_t totShift = 31 - shift;                 /* shift to apply after scaling */ 
00071   uint32_t blkCnt;                               /* loop counters  */ 
00072   arm_status status;                             /* status of matrix scaling      */ 
00073  
00074 #ifdef ARM_MATH_MATRIX_CHECK 
00075   /* Check for matrix mismatch  */ 
00076   if((pSrc->numRows != pDst->numRows) || (pSrc->numCols != pDst->numCols)) 
00077   { 
00078     /* Set status as ARM_MATH_SIZE_MISMATCH */ 
00079     status = ARM_MATH_SIZE_MISMATCH; 
00080   } 
00081   else 
00082 #endif 
00083   { 
00084     /* Total number of samples in the input matrix */ 
00085     numSamples = (uint32_t) pSrc->numRows * pSrc->numCols; 
00086  
00087     /* Loop Unrolling */ 
00088     blkCnt = numSamples >> 2u; 
00089  
00090     /* First part of the processing with loop unrolling.  Compute 4 outputs at a time.  
00091      ** a second loop below computes the remaining 1 to 3 samples. */ 
00092     while(blkCnt > 0u) 
00093     { 
00094       /* C(m,n) = A(m,n) * k */ 
00095       /* Scale, saturate and then store the results in the destination buffer. */ 
00096       out = ((q63_t) * pIn++ * scaleFract) >> totShift; 
00097       *pOut++ = clip_q63_to_q31(out); 
00098       out = ((q63_t) * pIn++ * scaleFract) >> totShift; 
00099       *pOut++ = clip_q63_to_q31(out); 
00100       out = ((q63_t) * pIn++ * scaleFract) >> totShift; 
00101       *pOut++ = clip_q63_to_q31(out); 
00102       out = ((q63_t) * pIn++ * scaleFract) >> totShift; 
00103       *pOut++ = clip_q63_to_q31(out); 
00104  
00105       /* Decrement the numSamples loop counter */ 
00106       blkCnt--; 
00107     } 
00108  
00109     /* If the numSamples is not a multiple of 4, compute any remaining output samples here.  
00110      ** No loop unrolling is used. */ 
00111     blkCnt = numSamples % 0x4u; 
00112  
00113     while(blkCnt > 0u) 
00114     { 
00115       /* C(m,n) = A(m,n) * k */ 
00116       /* Scale, saturate and then store the results in the destination buffer. */ 
00117       out = ((q63_t) * pIn++ * scaleFract) >> totShift; 
00118       *pOut++ = clip_q63_to_q31(out); 
00119  
00120       /* Decrement the numSamples loop counter */ 
00121       blkCnt--; 
00122     } 
00123  
00124     /* Set status as ARM_MATH_SUCCESS */ 
00125     status = ARM_MATH_SUCCESS; 
00126   } 
00127  
00128   /* Return to application */ 
00129   return (status); 
00130 } 
00131  
00132 /**  
00133  * @} end of MatrixScale group  
00134  */