From 4447282260be0780eb6e36f5e953bf56888a5688 Mon Sep 17 00:00:00 2001
From: px4dev <px4@purgatory.org>
Date: Sun, 6 Jan 2013 12:52:05 -0800
Subject: Integrate the interesting parts of the CMSIS 3.01 (r3p1) DSP library

---
 .../Source/SupportFunctions/arm_q31_to_q15.c       | 137 +++++++++++++++++++++
 1 file changed, 137 insertions(+)
 create mode 100644 apps/mathlib/CMSIS/DSP_Lib/Source/SupportFunctions/arm_q31_to_q15.c

(limited to 'apps/mathlib/CMSIS/DSP_Lib/Source/SupportFunctions/arm_q31_to_q15.c')

diff --git a/apps/mathlib/CMSIS/DSP_Lib/Source/SupportFunctions/arm_q31_to_q15.c b/apps/mathlib/CMSIS/DSP_Lib/Source/SupportFunctions/arm_q31_to_q15.c
new file mode 100644
index 000000000..ba79f85a1
--- /dev/null
+++ b/apps/mathlib/CMSIS/DSP_Lib/Source/SupportFunctions/arm_q31_to_q15.c
@@ -0,0 +1,137 @@
+/* ----------------------------------------------------------------------------    
+* Copyright (C) 2010 ARM Limited. All rights reserved.    
+*    
+* $Date:        15. February 2012  
+* $Revision: 	V1.1.0  
+*    
+* Project: 	    CMSIS DSP Library    
+* Title:		arm_q31_to_q15.c    
+*    
+* Description:	Converts the elements of the Q31 vector to Q15 vector.    
+*    
+* 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.    
+* ---------------------------------------------------------------------------- */
+
+#include "arm_math.h"
+
+/**    
+ * @ingroup groupSupport    
+ */
+
+/**    
+ * @addtogroup q31_to_x    
+ * @{    
+ */
+
+/**    
+ * @brief Converts the elements of the Q31 vector to Q15 vector.    
+ * @param[in]       *pSrc points to the Q31 input vector    
+ * @param[out]      *pDst points to the Q15 output vector   
+ * @param[in]       blockSize length of the input vector    
+ * @return none.    
+ *     
+ * \par Description:    
+ *    
+ * The equation used for the conversion process is:    
+ *   
+ * <pre>    
+ * 	pDst[n] = (q15_t) pSrc[n] >> 16;   0 <= n < blockSize.    
+ * </pre>    
+ *   
+ */
+
+
+void arm_q31_to_q15(
+  q31_t * pSrc,
+  q15_t * pDst,
+  uint32_t blockSize)
+{
+  q31_t *pIn = pSrc;                             /* Src pointer */
+  uint32_t blkCnt;                               /* loop counter */
+
+#ifndef ARM_MATH_CM0
+
+  /* Run the below code for Cortex-M4 and Cortex-M3 */
+  q31_t in1, in2, in3, in4;
+  q31_t out1, out2;
+
+  /*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)
+  {
+    /* C = (q15_t) A >> 16 */
+    /* convert from q31 to q15 and then store the results in the destination buffer */
+    in1 = *pIn++;
+    in2 = *pIn++;
+    in3 = *pIn++;
+    in4 = *pIn++;
+
+    /* pack two higher 16-bit values from two 32-bit values */
+#ifndef ARM_MATH_BIG_ENDIAN
+
+    out1 = __PKHTB(in2, in1, 16);
+    out2 = __PKHTB(in4, in3, 16);
+
+#else
+
+    out1 = __PKHTB(in1, in2, 16);
+    out2 = __PKHTB(in3, in4, 16);
+
+#endif //      #ifdef ARM_MATH_BIG_ENDIAN
+
+    *__SIMD32(pDst)++ = out1;
+    *__SIMD32(pDst)++ = out2;
+
+    /* 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 */
+
+  /* Loop over blockSize number of values */
+  blkCnt = blockSize;
+
+#endif /* #ifndef ARM_MATH_CM0 */
+
+  while(blkCnt > 0u)
+  {
+    /* C = (q15_t) A >> 16 */
+    /* convert from q31 to q15 and then store the results in the destination buffer */
+    *pDst++ = (q15_t) (*pIn++ >> 16);
+
+    /* Decrement the loop counter */
+    blkCnt--;
+  }
+
+}
+
+/**    
+ * @} end of q31_to_x group    
+ */
-- 
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