Diff: src/Cortex-M4-M3/SupportFunctions/arm_float_to_q15.c

Revision:

0:1014af42efd9

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/Cortex-M4-M3/SupportFunctions/arm_float_to_q15.c	Thu Mar 10 15:07:50 2011 +0000
@@ -0,0 +1,152 @@
+/* ----------------------------------------------------------------------------  
+* Copyright (C) 2010 ARM Limited. All rights reserved.  
+*  
+* $Date:        29. November 2010  
+* $Revision: 	V1.0.3  
+*  
+* Project: 	    CMSIS DSP Library  
+* Title:		arm_float_to_q15.c  
+*  
+* Description:	Processing function for the Conversion from float to Q15  
+*  
+* 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.  
+* ---------------------------------------------------------------------------- */ 
+ 
+#include "arm_math.h" 
+ 
+/**  
+ * @ingroup groupSupport  
+ */ 
+ 
+/**  
+ * @addtogroup float_to_x  
+ * @{  
+ */ 
+ 
+/**  
+ * @brief Converts the elements of the floating-point vector to Q15 vector.  
+ * @param[in]       *pSrc points to the floating-point input vector  
+ * @param[out]      *pDst points to the Q15 output vector 
+ * @param[in]       blockSize length of the input vector  
+ * @return none.  
+ *  
+ * \par Description:  
+ * \par 
+ * The equation used for the conversion process is:  
+ * <pre>  
+ * 	pDst[n] = (q15_t)(pSrc[n] * 32768);   0 <= n < blockSize.  
+ * </pre>  
+ * \par Scaling and Overflow Behavior:  
+ * \par  
+ * The function uses saturating arithmetic.  
+ * Results outside of the allowable Q15 range [0x8000 0x7FFF] will be saturated.  
+ * \note 
+ * In order to apply rounding, the library should be rebuilt with the ROUNDING macro   
+ * defined in the preprocessor section of project options.   
+ *  
+ */ 
+ 
+ 
+void arm_float_to_q15( 
+  float32_t * pSrc, 
+  q15_t * pDst, 
+  uint32_t blockSize) 
+{ 
+  float32_t *pIn = pSrc;                         /* Src pointer */ 
+  uint32_t blkCnt;                               /* loop counter */ 
+ 
+#ifdef ARM_MATH_ROUNDING 
+ 
+  float32_t in; 
+ 
+#endif 
+ 
+  /*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) 
+  { 
+ 
+#ifdef ARM_MATH_ROUNDING 
+    /* C = A * 32768 */ 
+    /* convert from float to q15 and then store the results in the destination buffer */ 
+    in = *pIn++; 
+    in = (in * 32768.0f); 
+    in += in > 0 ? 0.5 : -0.5; 
+    *pDst++ = (q15_t) (__SSAT((q31_t) (in), 16)); 
+ 
+    in = *pIn++; 
+    in = (in * 32768.0f); 
+    in += in > 0 ? 0.5 : -0.5; 
+    *pDst++ = (q15_t) (__SSAT((q31_t) (in), 16)); 
+ 
+    in = *pIn++; 
+    in = (in * 32768.0f); 
+    in += in > 0 ? 0.5 : -0.5; 
+    *pDst++ = (q15_t) (__SSAT((q31_t) (in), 16)); 
+ 
+    in = *pIn++; 
+    in = (in * 32768.0f); 
+    in += in > 0 ? 0.5 : -0.5; 
+    *pDst++ = (q15_t) (__SSAT((q31_t) (in), 16)); 
+ 
+#else 
+ 
+    /* C = A * 32768 */ 
+    /* convert from float to q15 and then store the results in the destination buffer */ 
+    *pDst++ = (q15_t) __SSAT((q31_t) (*pIn++ * 32768.0f), 16); 
+    *pDst++ = (q15_t) __SSAT((q31_t) (*pIn++ * 32768.0f), 16); 
+    *pDst++ = (q15_t) __SSAT((q31_t) (*pIn++ * 32768.0f), 16); 
+    *pDst++ = (q15_t) __SSAT((q31_t) (*pIn++ * 32768.0f), 16); 
+ 
+#endif 
+ 
+    /* 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) 
+  { 
+ 
+#ifdef ARM_MATH_ROUNDING 
+    /* C = A * 32768 */ 
+    /* convert from float to q15 and then store the results in the destination buffer */ 
+    in = *pIn++; 
+    in = (in * 32768LL); 
+    in += in > 0 ? 0.5 : -0.5; 
+    *pDst++ = (q15_t) (__SSAT((q31_t) (in), 16)); 
+ 
+#else 
+ 
+    /* C = A * 32768 */ 
+    /* convert from float to q15 and then store the results in the destination buffer */ 
+    *pDst++ = (q15_t) __SSAT((q31_t) (*pIn++ * 32768.0f), 16); 
+ 
+#endif 
+ 
+    /* Decrement the loop counter */ 
+    blkCnt--; 
+  } 
+} 
+ 
+/**  
+ * @} end of float_to_x group  
+ */