Diff: cmsis_dsp/BasicMathFunctions/arm_scale_q31.c

Revision:

1:fdd22bb7aa52

Child:

2:da51fb522205

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/cmsis_dsp/BasicMathFunctions/arm_scale_q31.c	Wed Nov 28 12:30:09 2012 +0000
@@ -0,0 +1,223 @@
+/* ----------------------------------------------------------------------
+* Copyright (C) 2010 ARM Limited. All rights reserved.
+*
+* $Date:        15. May 2012
+* $Revision:     V1.1.0
+*
+* Project:         CMSIS DSP Library
+* Title:        arm_scale_q31.c
+*
+* Description:    Multiplies a Q31 vector by a scalar.
+*
+* 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
+ */
+
+/**
+ * @addtogroup scale
+ * @{
+ */
+
+/**
+ * @brief Multiplies a Q31 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 1.31 format.
+ * These are multiplied to yield a 2.62 intermediate result and this is shifted with saturation to 1.31 format.
+ */
+
+void arm_scale_q31(
+  q31_t * pSrc,
+  q31_t scaleFract,
+  int8_t shift,
+  q31_t * pDst,
+  uint32_t blockSize)
+{
+  int8_t kShift = shift + 1;                     /* Shift to apply after scaling */
+  int8_t sign = (kShift & 0x80);
+  uint32_t blkCnt;                               /* loop counter */
+  q31_t in, out;
+
+#ifndef ARM_MATH_CM0
+
+/* Run the below code for Cortex-M4 and Cortex-M3 */
+
+  q31_t in1, in2, in3, in4;                      /* temporary input variables */
+  q31_t out1, out2, out3, out4;                  /* temporary output variabels */
+
+
+  /*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)
+    {
+      /* read four inputs from source */
+      in1 = *pSrc;
+      in2 = *(pSrc + 1);
+      in3 = *(pSrc + 2);
+      in4 = *(pSrc + 3);
+
+      /* multiply input with scaler value */
+      in1 = ((q63_t) in1 * scaleFract) >> 32;
+      in2 = ((q63_t) in2 * scaleFract) >> 32;
+      in3 = ((q63_t) in3 * scaleFract) >> 32;
+      in4 = ((q63_t) in4 * scaleFract) >> 32;
+
+      /* apply shifting */
+      out1 = in1 << kShift;
+      out2 = in2 << kShift;
+
+      /* saturate the results. */
+      if(in1 != (out1 >> kShift))
+        out1 = 0x7FFFFFFF ^ (in1 >> 31);
+
+      if(in2 != (out2 >> kShift))
+        out2 = 0x7FFFFFFF ^ (in2 >> 31);
+
+      out3 = in3 << kShift;
+      out4 = in4 << kShift;
+
+      *pDst = out1;
+      *(pDst + 1) = out2;
+
+      if(in3 != (out3 >> kShift))
+        out3 = 0x7FFFFFFF ^ (in3 >> 31);
+
+      if(in4 != (out4 >> kShift))
+        out4 = 0x7FFFFFFF ^ (in4 >> 31);
+
+      /* Store result destination */
+      *(pDst + 2) = out3;
+      *(pDst + 3) = out4;
+
+      /* Update pointers to process next sampels */
+      pSrc += 4u;
+      pDst += 4u;
+
+      /* Decrement the loop counter */
+      blkCnt--;
+    }
+
+  }
+  else
+  {
+    kShift = -kShift;
+
+    /* 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)
+    {
+      /* read four inputs from source */
+      in1 = *pSrc;
+      in2 = *(pSrc + 1);
+      in3 = *(pSrc + 2);
+      in4 = *(pSrc + 3);
+
+      /* multiply input with scaler value */
+      in1 = ((q63_t) in1 * scaleFract) >> 32;
+      in2 = ((q63_t) in2 * scaleFract) >> 32;
+      in3 = ((q63_t) in3 * scaleFract) >> 32;
+      in4 = ((q63_t) in4 * scaleFract) >> 32;
+
+      /* apply shifting */
+      out1 = in1 >> kShift;
+      out2 = in2 >> kShift;
+
+      out3 = in3 >> kShift;
+      out4 = in4 >> kShift;
+
+      /* Store result destination */
+      *pDst = out1;
+      *(pDst + 1) = out2;
+
+      *(pDst + 2) = out3;
+      *(pDst + 3) = out4;
+
+      /* Update pointers to process next sampels */
+      pSrc += 4u;
+      pDst += 4u;
+
+      /* 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;
+
+#else
+
+  /* Run the below code for Cortex-M0 */
+  if(sign != 0u)
+    kShift = -kShift;
+
+  /* Initialize blkCnt with number of samples */
+  blkCnt = blockSize;
+
+#endif /* #ifndef ARM_MATH_CM0 */
+
+  while(blkCnt > 0u)
+  {
+    /* C = A * scale */
+    /* Scale the input and then store the result in the destination buffer. */
+    in = *pSrc++;
+    in = ((q63_t) in * scaleFract) >> 32;
+
+    if(sign == 0)
+    {
+      out = in << kShift;
+      if(in != (out >> kShift))
+        out = 0x7FFFFFFF ^ (in >> 31);
+    }
+    else
+    {
+      out = in >> kShift;
+    }
+
+    *pDst++ = out;
+
+    /* Decrement the loop counter */
+    blkCnt--;
+  }
+}
+
+/**
+ * @} end of scale group
+ */