Diff: cmsis_dsp/FilteringFunctions/arm_biquad_cascade_df1_q15.c

Revision:

1:fdd22bb7aa52

Child:

2:da51fb522205

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/cmsis_dsp/FilteringFunctions/arm_biquad_cascade_df1_q15.c	Wed Nov 28 12:30:09 2012 +0000
@@ -0,0 +1,408 @@
+/* ----------------------------------------------------------------------    
+* Copyright (C) 2010 ARM Limited. All rights reserved.    
+*    
+* $Date:        15. February 2012  
+* $Revision:     V1.1.0  
+*    
+* Project:         CMSIS DSP Library    
+* Title:        arm_biquad_cascade_df1_q15.c    
+*    
+* Description:    Processing function for the    
+*                Q15 Biquad cascade DirectFormI(DF1) filter.    
+*    
+* 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 0.0.5  2010/04/26     
+*      incorporated review comments and updated with latest CMSIS layer    
+*    
+* Version 0.0.3  2010/03/10     
+*    Initial version    
+* -------------------------------------------------------------------- */
+
+#include "arm_math.h"
+
+/**    
+ * @ingroup groupFilters    
+ */
+
+/**    
+ * @addtogroup BiquadCascadeDF1    
+ * @{    
+ */
+
+/**    
+ * @brief Processing function for the Q15 Biquad cascade filter.    
+ * @param[in]  *S points to an instance of the Q15 Biquad cascade structure.    
+ * @param[in]  *pSrc points to the block of input data.    
+ * @param[out] *pDst points to the location where the output result is written.    
+ * @param[in]  blockSize number of samples to process per call.    
+ * @return none.    
+ *    
+ *    
+ * <b>Scaling and Overflow Behavior:</b>    
+ * \par    
+ * The function is implemented using a 64-bit internal accumulator.    
+ * Both coefficients and state variables are represented in 1.15 format and multiplications yield a 2.30 result.    
+ * The 2.30 intermediate results are accumulated in a 64-bit accumulator in 34.30 format.    
+ * There is no risk of internal overflow with this approach and the full precision of intermediate multiplications is preserved.    
+ * The accumulator is then shifted by <code>postShift</code> bits to truncate the result to 1.15 format by discarding the low 16 bits.    
+ * Finally, the result is saturated to 1.15 format.    
+ *    
+ * \par    
+ * Refer to the function <code>arm_biquad_cascade_df1_fast_q15()</code> for a faster but less precise implementation of this filter for Cortex-M3 and Cortex-M4.    
+ */
+
+void arm_biquad_cascade_df1_q15(
+  const arm_biquad_casd_df1_inst_q15 * S,
+  q15_t * pSrc,
+  q15_t * pDst,
+  uint32_t blockSize)
+{
+
+
+#ifndef ARM_MATH_CM0
+
+  /* Run the below code for Cortex-M4 and Cortex-M3 */
+
+  q15_t *pIn = pSrc;                             /*  Source pointer                               */
+  q15_t *pOut = pDst;                            /*  Destination pointer                          */
+  q31_t in;                                      /*  Temporary variable to hold input value       */
+  q31_t out;                                     /*  Temporary variable to hold output value      */
+  q31_t b0;                                      /*  Temporary variable to hold bo value          */
+  q31_t b1, a1;                                  /*  Filter coefficients                          */
+  q31_t state_in, state_out;                     /*  Filter state variables                       */
+  q31_t acc_l, acc_h;
+  q63_t acc;                                     /*  Accumulator                                  */
+  int32_t lShift = (15 - (int32_t) S->postShift);       /*  Post shift                                   */
+  q15_t *pState = S->pState;                     /*  State pointer                                */
+  q15_t *pCoeffs = S->pCoeffs;                   /*  Coefficient pointer                          */
+  uint32_t sample, stage = (uint32_t) S->numStages;     /*  Stage loop counter                           */
+  int32_t uShift = (32 - lShift);
+
+  do
+  {
+    /* Read the b0 and 0 coefficients using SIMD  */
+    b0 = *__SIMD32(pCoeffs)++;
+
+    /* Read the b1 and b2 coefficients using SIMD */
+    b1 = *__SIMD32(pCoeffs)++;
+
+    /* Read the a1 and a2 coefficients using SIMD */
+    a1 = *__SIMD32(pCoeffs)++;
+
+    /* Read the input state values from the state buffer:  x[n-1], x[n-2] */
+    state_in = *__SIMD32(pState)++;
+
+    /* Read the output state values from the state buffer:  y[n-1], y[n-2] */
+    state_out = *__SIMD32(pState)--;
+
+    /* Apply loop unrolling and compute 2 output values simultaneously. */
+    /*      The variable acc hold output values that are being computed:    
+     *    
+     *    acc =  b0 * x[n] + b1 * x[n-1] + b2 * x[n-2] + a1 * y[n-1] + a2 * y[n-2]    
+     *    acc =  b0 * x[n] + b1 * x[n-1] + b2 * x[n-2] + a1 * y[n-1] + a2 * y[n-2]    
+     */
+    sample = blockSize >> 1u;
+
+    /* First part of the processing with loop unrolling.  Compute 2 outputs at a time.    
+     ** a second loop below computes the remaining 1 sample. */
+    while(sample > 0u)
+    {
+
+      /* Read the input */
+      in = *__SIMD32(pIn)++;
+
+      /* out =  b0 * x[n] + 0 * 0 */
+      out = __SMUAD(b0, in);
+
+      /* acc +=  b1 * x[n-1] +  b2 * x[n-2] + out */
+      acc = __SMLALD(b1, state_in, out);
+      /* acc +=  a1 * y[n-1] +  a2 * y[n-2] */
+      acc = __SMLALD(a1, state_out, acc);
+
+      /* The result is converted from 3.29 to 1.31 if postShift = 1, and then saturation is applied */
+      /* Calc lower part of acc */
+      acc_l = acc & 0xffffffff;
+
+      /* Calc upper part of acc */
+      acc_h = (acc >> 32) & 0xffffffff;
+
+      /* Apply shift for lower part of acc and upper part of acc */
+      out = (uint32_t) acc_l >> lShift | acc_h << uShift;
+
+      out = __SSAT(out, 16);
+
+      /* Every time after the output is computed state should be updated. */
+      /* The states should be updated as:  */
+      /* Xn2 = Xn1    */
+      /* Xn1 = Xn     */
+      /* Yn2 = Yn1    */
+      /* Yn1 = acc   */
+      /* x[n-N], x[n-N-1] are packed together to make state_in of type q31 */
+      /* y[n-N], y[n-N-1] are packed together to make state_out of type q31 */
+
+#ifndef  ARM_MATH_BIG_ENDIAN
+
+      state_in = __PKHBT(in, state_in, 16);
+      state_out = __PKHBT(out, state_out, 16);
+
+#else
+
+      state_in = __PKHBT(state_in >> 16, (in >> 16), 16);
+      state_out = __PKHBT(state_out >> 16, (out), 16);
+
+#endif /*      #ifndef  ARM_MATH_BIG_ENDIAN    */
+
+      /* out =  b0 * x[n] + 0 * 0 */
+      out = __SMUADX(b0, in);
+      /* acc +=  b1 * x[n-1] +  b2 * x[n-2] + out */
+      acc = __SMLALD(b1, state_in, out);
+      /* acc +=  a1 * y[n-1] + a2 * y[n-2] */
+      acc = __SMLALD(a1, state_out, acc);
+
+      /* The result is converted from 3.29 to 1.31 if postShift = 1, and then saturation is applied */
+      /* Calc lower part of acc */
+      acc_l = acc & 0xffffffff;
+
+      /* Calc upper part of acc */
+      acc_h = (acc >> 32) & 0xffffffff;
+
+      /* Apply shift for lower part of acc and upper part of acc */
+      out = (uint32_t) acc_l >> lShift | acc_h << uShift;
+
+      out = __SSAT(out, 16);
+
+      /* Store the output in the destination buffer. */
+
+#ifndef  ARM_MATH_BIG_ENDIAN
+
+      *__SIMD32(pOut)++ = __PKHBT(state_out, out, 16);
+
+#else
+
+      *__SIMD32(pOut)++ = __PKHBT(out, state_out >> 16, 16);
+
+#endif /*      #ifndef  ARM_MATH_BIG_ENDIAN    */
+
+      /* Every time after the output is computed state should be updated. */
+      /* The states should be updated as:  */
+      /* Xn2 = Xn1    */
+      /* Xn1 = Xn     */
+      /* Yn2 = Yn1    */
+      /* Yn1 = acc   */
+      /* x[n-N], x[n-N-1] are packed together to make state_in of type q31 */
+      /* y[n-N], y[n-N-1] are packed together to make state_out of type q31 */
+#ifndef  ARM_MATH_BIG_ENDIAN
+
+      state_in = __PKHBT(in >> 16, state_in, 16);
+      state_out = __PKHBT(out, state_out, 16);
+
+#else
+
+      state_in = __PKHBT(state_in >> 16, in, 16);
+      state_out = __PKHBT(state_out >> 16, out, 16);
+
+#endif /*      #ifndef  ARM_MATH_BIG_ENDIAN    */
+
+
+      /* Decrement the loop counter */
+      sample--;
+
+    }
+
+    /* If the blockSize is not a multiple of 2, compute any remaining output samples here.    
+     ** No loop unrolling is used. */
+
+    if((blockSize & 0x1u) != 0u)
+    {
+      /* Read the input */
+      in = *pIn++;
+
+      /* out =  b0 * x[n] + 0 * 0 */
+
+#ifndef  ARM_MATH_BIG_ENDIAN
+
+      out = __SMUAD(b0, in);
+
+#else
+
+      out = __SMUADX(b0, in);
+
+#endif /*      #ifndef  ARM_MATH_BIG_ENDIAN    */
+
+      /* acc =  b1 * x[n-1] + b2 * x[n-2] + out */
+      acc = __SMLALD(b1, state_in, out);
+      /* acc +=  a1 * y[n-1] + a2 * y[n-2] */
+      acc = __SMLALD(a1, state_out, acc);
+
+      /* The result is converted from 3.29 to 1.31 if postShift = 1, and then saturation is applied */
+      /* Calc lower part of acc */
+      acc_l = acc & 0xffffffff;
+
+      /* Calc upper part of acc */
+      acc_h = (acc >> 32) & 0xffffffff;
+
+      /* Apply shift for lower part of acc and upper part of acc */
+      out = (uint32_t) acc_l >> lShift | acc_h << uShift;
+
+      out = __SSAT(out, 16);
+
+      /* Store the output in the destination buffer. */
+      *pOut++ = (q15_t) out;
+
+      /* Every time after the output is computed state should be updated. */
+      /* The states should be updated as:  */
+      /* Xn2 = Xn1    */
+      /* Xn1 = Xn     */
+      /* Yn2 = Yn1    */
+      /* Yn1 = acc   */
+      /* x[n-N], x[n-N-1] are packed together to make state_in of type q31 */
+      /* y[n-N], y[n-N-1] are packed together to make state_out of type q31 */
+
+#ifndef  ARM_MATH_BIG_ENDIAN
+
+      state_in = __PKHBT(in, state_in, 16);
+      state_out = __PKHBT(out, state_out, 16);
+
+#else
+
+      state_in = __PKHBT(state_in >> 16, in, 16);
+      state_out = __PKHBT(state_out >> 16, out, 16);
+
+#endif /*   #ifndef  ARM_MATH_BIG_ENDIAN    */
+
+    }
+
+    /*  The first stage goes from the input wire to the output wire.  */
+    /*  Subsequent numStages occur in-place in the output wire  */
+    pIn = pDst;
+
+    /* Reset the output pointer */
+    pOut = pDst;
+
+    /*  Store the updated state variables back into the state array */
+    *__SIMD32(pState)++ = state_in;
+    *__SIMD32(pState)++ = state_out;
+
+
+    /* Decrement the loop counter */
+    stage--;
+
+  } while(stage > 0u);
+
+#else
+
+  /* Run the below code for Cortex-M0 */
+
+  q15_t *pIn = pSrc;                             /*  Source pointer                               */
+  q15_t *pOut = pDst;                            /*  Destination pointer                          */
+  q15_t b0, b1, b2, a1, a2;                      /*  Filter coefficients           */
+  q15_t Xn1, Xn2, Yn1, Yn2;                      /*  Filter state variables        */
+  q15_t Xn;                                      /*  temporary input               */
+  q63_t acc;                                     /*  Accumulator                                  */
+  int32_t shift = (15 - (int32_t) S->postShift); /*  Post shift                                   */
+  q15_t *pState = S->pState;                     /*  State pointer                                */
+  q15_t *pCoeffs = S->pCoeffs;                   /*  Coefficient pointer                          */
+  uint32_t sample, stage = (uint32_t) S->numStages;     /*  Stage loop counter                           */
+
+  do
+  {
+    /* Reading the coefficients */
+    b0 = *pCoeffs++;
+    b1 = *pCoeffs++;
+    b2 = *pCoeffs++;
+    a1 = *pCoeffs++;
+    a2 = *pCoeffs++;
+
+    /* Reading the state values */
+    Xn1 = pState[0];
+    Xn2 = pState[1];
+    Yn1 = pState[2];
+    Yn2 = pState[3];
+
+    /*      The variables acc holds the output value that is computed:         
+     *    acc =  b0 * x[n] + b1 * x[n-1] + b2 * x[n-2] + a1 * y[n-1] + a2 * y[n-2]         
+     */
+
+    sample = blockSize;
+
+    while(sample > 0u)
+    {
+      /* Read the input */
+      Xn = *pIn++;
+
+      /* acc =  b0 * x[n] + b1 * x[n-1] + b2 * x[n-2] + a1 * y[n-1] + a2 * y[n-2] */
+      /* acc =  b0 * x[n] */
+      acc = (q31_t) b0 *Xn;
+
+      /* acc +=  b1 * x[n-1] */
+      acc += (q31_t) b1 *Xn1;
+      /* acc +=  b[2] * x[n-2] */
+      acc += (q31_t) b2 *Xn2;
+      /* acc +=  a1 * y[n-1] */
+      acc += (q31_t) a1 *Yn1;
+      /* acc +=  a2 * y[n-2] */
+      acc += (q31_t) a2 *Yn2;
+
+      /* The result is converted to 1.31  */
+      acc = __SSAT((acc >> shift), 16);
+
+      /* Every time after the output is computed state should be updated. */
+      /* The states should be updated as:  */
+      /* Xn2 = Xn1    */
+      /* Xn1 = Xn     */
+      /* Yn2 = Yn1    */
+      /* Yn1 = acc    */
+      Xn2 = Xn1;
+      Xn1 = Xn;
+      Yn2 = Yn1;
+      Yn1 = (q15_t) acc;
+
+      /* Store the output in the destination buffer. */
+      *pOut++ = (q15_t) acc;
+
+      /* decrement the loop counter */
+      sample--;
+    }
+
+    /*  The first stage goes from the input buffer to the output buffer. */
+    /*  Subsequent stages occur in-place in the output buffer */
+    pIn = pDst;
+
+    /* Reset to destination pointer */
+    pOut = pDst;
+
+    /*  Store the updated state variables back into the pState array */
+    *pState++ = Xn1;
+    *pState++ = Xn2;
+    *pState++ = Yn1;
+    *pState++ = Yn2;
+
+  } while(--stage);
+
+#endif /*     #ifndef ARM_MATH_CM0 */
+
+}
+
+
+/**    
+ * @} end of BiquadCascadeDF1 group    
+ */