Diff: src/Cortex-M4-M3/BasicMathFunctions/arm_scale_q15.c

Revision:

0:1014af42efd9

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/Cortex-M4-M3/BasicMathFunctions/arm_scale_q15.c	Thu Mar 10 15:07:50 2011 +0000
@@ -0,0 +1,114 @@
+/* ----------------------------------------------------------------------  
+* Copyright (C) 2010 ARM Limited. All rights reserved.  
+*  
+* $Date:        29. November 2010  
+* $Revision: 	V1.0.3  
+*  
+* Project: 	    CMSIS DSP Library  
+* Title:		arm_scale_q15.c  
+*  
+* Description:	Multiplies a Q15 vector by a scalar.  
+*  
+* Target Processor: Cortex-M4/Cortex-M3
+*  
+* Version 1.0.3 2010/11/29 
+*    Re-organized the CMSIS folders and updated documentation.  
+*   
+* Version 1.0.2 2010/11/11  
+*    Documentation updated.   
+*  
+* Version 1.0.1 2010/10/05   
+*    Production release and review comments incorporated.  
+*  
+* Version 1.0.0 2010/09/20   
+*    Production release and review comments incorporated  
+*  
+* Version 0.0.7  2010/06/10   
+*    Misra-C changes done  
+* -------------------------------------------------------------------- */ 
+ 
+#include "arm_math.h" 
+ 
+/**  
+ * @ingroup groupMath  
+ */ 
+ 
+/**  
+ * @addtogroup scale  
+ * @{  
+ */ 
+ 
+/**  
+ * @brief Multiplies a Q15 vector by a scalar.  
+ * @param[in]       *pSrc points to the input vector  
+ * @param[in]       scaleFract fractional portion of the scale value  
+ * @param[in]       shift number of bits to shift the result by  
+ * @param[out]      *pDst points to the output vector  
+ * @param[in]       blockSize number of samples in the vector  
+ * @return none.  
+ *  
+ * <b>Scaling and Overflow Behavior:</b>  
+ * \par  
+ * The input data <code>*pSrc</code> and <code>scaleFract</code> are in 1.15 format.  
+ * These are multiplied to yield a 2.30 intermediate result and this is shifted with saturation to 1.15 format.  
+ */ 
+ 
+ 
+void arm_scale_q15( 
+  q15_t * pSrc, 
+  q15_t scaleFract, 
+  int8_t shift, 
+  q15_t * pDst, 
+  uint32_t blockSize) 
+{ 
+  int8_t kShift = 15 - shift;                    /* shift to apply after scaling */ 
+  uint32_t blkCnt;                               /* loop counter */ 
+  q15_t in1, in2;                                /* Temporary variables */ 
+ 
+ 
+  /*loop Unrolling */ 
+  blkCnt = blockSize >> 2u; 
+ 
+  /* First part of the processing with loop unrolling.  Compute 4 outputs at a time.  
+   ** a second loop below computes the remaining 1 to 3 samples. */ 
+  while(blkCnt > 0u) 
+  { 
+    /* Reading 2 inputs from memory */ 
+    in1 = *pSrc++; 
+    in2 = *pSrc++; 
+    /* C = A * scale */ 
+    /* Scale the inputs and then store the 2 results in the destination buffer  
+     * in single cycle by packing the outputs */ 
+    *__SIMD32(pDst)++ = 
+      __PKHBT(__SSAT((in1 * scaleFract) >> kShift, 16), 
+              __SSAT((in2 * scaleFract) >> kShift, 16), 16); 
+ 
+    in1 = *pSrc++; 
+    in2 = *pSrc++; 
+ 
+    *__SIMD32(pDst)++ = 
+      __PKHBT(__SSAT((in1 * scaleFract) >> kShift, 16), 
+              __SSAT((in2 * scaleFract) >> kShift, 16), 16); 
+ 
+    /* Decrement the loop counter */ 
+    blkCnt--; 
+  } 
+ 
+  /* If the blockSize is not a multiple of 4, compute any remaining output samples here.  
+   ** No loop unrolling is used. */ 
+  blkCnt = blockSize % 0x4u; 
+ 
+  while(blkCnt > 0u) 
+  { 
+    /* C = A * scale */ 
+    /* Scale the input and then store the result in the destination buffer. */ 
+    *pDst++ = (q15_t) (__SSAT(((*pSrc++) * scaleFract) >> kShift, 16)); 
+ 
+    /* Decrement the loop counter */ 
+    blkCnt--; 
+  } 
+} 
+ 
+/**  
+ * @} end of scale group  
+ */