Diff: cmsis_dsp/BasicMathFunctions/arm_shift_q31.c

Revision:

1:fdd22bb7aa52

Child:

2:da51fb522205

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/cmsis_dsp/BasicMathFunctions/arm_shift_q31.c	Wed Nov 28 12:30:09 2012 +0000
@@ -0,0 +1,195 @@
+/* ----------------------------------------------------------------------    
+* Copyright (C) 2010 ARM Limited. All rights reserved.    
+*    
+* $Date:        15. February 2012  
+* $Revision:     V1.1.0  
+*    
+* Project:         CMSIS DSP Library    
+* Title:        arm_shift_q31.c    
+*    
+* Description:    Shifts the elements of a Q31 vector by a specified number of bits.    
+*    
+* Target Processor: Cortex-M4/Cortex-M3/Cortex-M0
+*  
+* Version 1.1.0 2012/02/15 
+*    Updated with more optimizations, bug fixes and minor API changes.  
+*   
+* Version 1.0.10 2011/7/15  
+*    Big Endian support added and Merged M0 and M3/M4 Source code.   
+*    
+* 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        
+ */
+/**        
+ * @defgroup shift Vector Shift        
+ *        
+ * Shifts the elements of a fixed-point vector by a specified number of bits.        
+ * There are separate functions for Q7, Q15, and Q31 data types.        
+ * The underlying algorithm used is:        
+ *        
+ * <pre>        
+ *     pDst[n] = pSrc[n] << shift,   0 <= n < blockSize.        
+ * </pre>        
+ *        
+ * If <code>shift</code> is positive then the elements of the vector are shifted to the left.        
+ * If <code>shift</code> is negative then the elements of the vector are shifted to the right.        
+ */
+
+/**        
+ * @addtogroup shift        
+ * @{        
+ */
+
+/**        
+ * @brief  Shifts the elements of a Q31 vector a specified number of bits.        
+ * @param[in]  *pSrc points to the input vector        
+ * @param[in]  shiftBits number of bits to shift.  A positive value shifts left; a negative value shifts right.        
+ * @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 function uses saturating arithmetic.        
+ * Results outside of the allowable Q31 range [0x80000000 0x7FFFFFFF] will be saturated.        
+ */
+
+void arm_shift_q31(
+  q31_t * pSrc,
+  int8_t shiftBits,
+  q31_t * pDst,
+  uint32_t blockSize)
+{
+  uint32_t blkCnt;                               /* loop counter */
+  uint8_t sign = (shiftBits & 0x80);             /* Sign of shiftBits */
+
+#ifndef ARM_MATH_CM0
+
+  q31_t in1, in2, in3, in4;                      /* Temporary input variables */
+  q31_t out1, out2, out3, out4;                  /* Temporary output variables */
+
+  /*loop Unrolling */
+  blkCnt = blockSize >> 2u;
+
+
+  if(sign == 0u)
+  {
+    /* 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)
+    {
+      /* C = A  << shiftBits */
+      /* Shift the input and then store the results in the destination buffer. */
+      in1 = *pSrc;
+      in2 = *(pSrc + 1);
+      out1 = in1 << shiftBits;
+      in3 = *(pSrc + 2);
+      out2 = in2 << shiftBits;
+      in4 = *(pSrc + 3);
+      if(in1 != (out1 >> shiftBits))
+        out1 = 0x7FFFFFFF ^ (in1 >> 31);
+
+      if(in2 != (out2 >> shiftBits))
+        out2 = 0x7FFFFFFF ^ (in2 >> 31);
+
+      *pDst = out1;
+      out3 = in3 << shiftBits;
+      *(pDst + 1) = out2;
+      out4 = in4 << shiftBits;
+
+      if(in3 != (out3 >> shiftBits))
+        out3 = 0x7FFFFFFF ^ (in3 >> 31);
+
+      if(in4 != (out4 >> shiftBits))
+        out4 = 0x7FFFFFFF ^ (in4 >> 31);
+
+      *(pDst + 2) = out3;
+      *(pDst + 3) = out4;
+
+      /* Update destination pointer to process next sampels */
+      pSrc += 4u;
+      pDst += 4u;
+
+      /* Decrement the loop counter */
+      blkCnt--;
+    }
+  }
+  else
+  {
+
+    /* 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)
+    {
+      /* C = A >>  shiftBits */
+      /* Shift the input and then store the results in the destination buffer. */
+      in1 = *pSrc;
+      in2 = *(pSrc + 1);
+      in3 = *(pSrc + 2);
+      in4 = *(pSrc + 3);
+
+      *pDst = (in1 >> -shiftBits);
+      *(pDst + 1) = (in2 >> -shiftBits);
+      *(pDst + 2) = (in3 >> -shiftBits);
+      *(pDst + 3) = (in4 >> -shiftBits);
+
+
+      pSrc += 4u;
+      pDst += 4u;
+
+      blkCnt--;
+    }
+
+  }
+
+  /* If the blockSize is not a multiple of 4, compute any remaining output samples here.    
+   ** No loop unrolling is used. */
+  blkCnt = blockSize % 0x4u;
+
+#else
+
+  /* Run the below code for Cortex-M0 */
+
+
+  /* Initialize blkCnt with number of samples */
+  blkCnt = blockSize;
+
+#endif /* #ifndef ARM_MATH_CM0 */
+
+
+  while(blkCnt > 0u)
+  {
+    /* C = A (>> or <<) shiftBits */
+    /* Shift the input and then store the result in the destination buffer. */
+    *pDst++ = (sign == 0u) ? clip_q63_to_q31((q63_t) * pSrc++ << shiftBits) :
+      (*pSrc++ >> -shiftBits);
+
+    /* Decrement the loop counter */
+    blkCnt--;
+  }
+
+
+}
+
+/**        
+ * @} end of shift group        
+ */