Diff: FilteringFunctions/arm_fir_init_q15.c

Revision:

0:3d9c67d97d6f

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/FilteringFunctions/arm_fir_init_q15.c	Mon Jul 28 15:03:15 2014 +0000
@@ -0,0 +1,154 @@
+/* ----------------------------------------------------------------------    
+* Copyright (C) 2010-2014 ARM Limited. All rights reserved.    
+*    
+* $Date:        12. March 2014
+* $Revision: 	V1.4.3
+*    
+* Project: 	    CMSIS DSP Library    
+* Title:        arm_fir_init_q15.c    
+*    
+* Description:  Q15 FIR filter initialization function.    
+*    
+* Target Processor: Cortex-M4/Cortex-M3/Cortex-M0
+*  
+* Redistribution and use in source and binary forms, with or without 
+* modification, are permitted provided that the following conditions
+* are met:
+*   - Redistributions of source code must retain the above copyright
+*     notice, this list of conditions and the following disclaimer.
+*   - Redistributions in binary form must reproduce the above copyright
+*     notice, this list of conditions and the following disclaimer in
+*     the documentation and/or other materials provided with the 
+*     distribution.
+*   - Neither the name of ARM LIMITED nor the names of its contributors
+*     may be used to endorse or promote products derived from this
+*     software without specific prior written permission.
+*
+* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE 
+* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+* POSSIBILITY OF SUCH DAMAGE.  
+* ------------------------------------------------------------------- */
+
+#include "arm_math.h"
+
+/**    
+ * @ingroup groupFilters    
+ */
+
+/**    
+ * @addtogroup FIR    
+ * @{    
+ */
+
+/**    
+ * @param[in,out]  *S points to an instance of the Q15 FIR filter structure.    
+ * @param[in] 	   numTaps  Number of filter coefficients in the filter. Must be even and greater than or equal to 4.    
+ * @param[in]      *pCoeffs points to the filter coefficients buffer.    
+ * @param[in]      *pState points to the state buffer.    
+ * @param[in]      blockSize is number of samples processed per call.    
+ * @return The function returns ARM_MATH_SUCCESS if initialization is successful or ARM_MATH_ARGUMENT_ERROR if    
+ * <code>numTaps</code> is not greater than or equal to 4 and even.    
+ *    
+ * <b>Description:</b>    
+ * \par    
+ * <code>pCoeffs</code> points to the array of filter coefficients stored in time reversed order:    
+ * <pre>    
+ *    {b[numTaps-1], b[numTaps-2], b[N-2], ..., b[1], b[0]}    
+ * </pre>    
+ * Note that <code>numTaps</code> must be even and greater than or equal to 4.    
+ * To implement an odd length filter simply increase <code>numTaps</code> by 1 and set the last coefficient to zero.    
+ * For example, to implement a filter with <code>numTaps=3</code> and coefficients    
+ * <pre>    
+ *     {0.3, -0.8, 0.3}    
+ * </pre>    
+ * set <code>numTaps=4</code> and use the coefficients:    
+ * <pre>    
+ *     {0.3, -0.8, 0.3, 0}.    
+ * </pre>    
+ * Similarly, to implement a two point filter    
+ * <pre>    
+ *     {0.3, -0.3}    
+ * </pre>    
+ * set <code>numTaps=4</code> and use the coefficients:    
+ * <pre>    
+ *     {0.3, -0.3, 0, 0}.    
+ * </pre>    
+ * \par    
+ * <code>pState</code> points to the array of state variables.    
+ * <code>pState</code> is of length <code>numTaps+blockSize</code>, when running on Cortex-M4 and Cortex-M3  and is of length <code>numTaps+blockSize-1</code>, when running on Cortex-M0 where <code>blockSize</code> is the number of input samples processed by each call to <code>arm_fir_q15()</code>.    
+ */
+
+arm_status arm_fir_init_q15(
+  arm_fir_instance_q15 * S,
+  uint16_t numTaps,
+  q15_t * pCoeffs,
+  q15_t * pState,
+  uint32_t blockSize)
+{
+  arm_status status;
+
+
+#ifndef ARM_MATH_CM0_FAMILY
+
+  /* Run the below code for Cortex-M4 and Cortex-M3 */
+
+  /* The Number of filter coefficients in the filter must be even and at least 4 */
+  if(numTaps & 0x1u)
+  {
+    status = ARM_MATH_ARGUMENT_ERROR;
+  }
+  else
+  {
+    /* Assign filter taps */
+    S->numTaps = numTaps;
+
+    /* Assign coefficient pointer */
+    S->pCoeffs = pCoeffs;
+
+    /* Clear the state buffer.  The size is always (blockSize + numTaps ) */
+    memset(pState, 0, (numTaps + (blockSize)) * sizeof(q15_t));
+
+    /* Assign state pointer */
+    S->pState = pState;
+
+    status = ARM_MATH_SUCCESS;
+  }
+
+  return (status);
+
+#else
+
+  /* Run the below code for Cortex-M0 */
+
+  /* Assign filter taps */
+  S->numTaps = numTaps;
+
+  /* Assign coefficient pointer */
+  S->pCoeffs = pCoeffs;
+
+  /* Clear the state buffer.  The size is always (blockSize + numTaps - 1) */
+  memset(pState, 0, (numTaps + (blockSize - 1u)) * sizeof(q15_t));
+
+  /* Assign state pointer */
+  S->pState = pState;
+
+  status = ARM_MATH_SUCCESS;
+
+  return (status);
+
+#endif /*  #ifndef ARM_MATH_CM0_FAMILY */
+
+}
+
+/**    
+ * @} end of FIR group    
+ */