Diff: cmsis_dsp/FilteringFunctions/arm_iir_lattice_q15.c

Revision:

1:fdd22bb7aa52

Child:

2:da51fb522205

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/cmsis_dsp/FilteringFunctions/arm_iir_lattice_q15.c	Wed Nov 28 12:30:09 2012 +0000
@@ -0,0 +1,459 @@
+/* ----------------------------------------------------------------------    
+* Copyright (C) 2010 ARM Limited. All rights reserved.    
+*    
+* $Date:        15. February 2012  
+* $Revision:     V1.1.0  
+*    
+* Project:         CMSIS DSP Library    
+* Title:        arm_iir_lattice_q15.c    
+*    
+* Description:    Q15 IIR lattice filter processing function.    
+*    
+* 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 groupFilters    
+ */
+
+/**    
+ * @addtogroup IIR_Lattice    
+ * @{    
+ */
+
+/**    
+ * @brief Processing function for the Q15 IIR lattice filter.    
+ * @param[in] *S points to an instance of the Q15 IIR lattice structure.    
+ * @param[in] *pSrc points to the block of input data.    
+ * @param[out] *pDst points to the block of output data.    
+ * @param[in] blockSize number of samples to process.    
+ * @return none.    
+ *    
+ * @details    
+ * <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.    
+ * After all additions have been performed, the accumulator is truncated to 34.15 format by discarding low 15 bits.    
+ * Lastly, the accumulator is saturated to yield a result in 1.15 format.    
+ */
+
+void arm_iir_lattice_q15(
+  const arm_iir_lattice_instance_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 */
+
+  q31_t fcurr, fnext, gcurr = 0, gnext;          /* Temporary variables for lattice stages */
+  q15_t gnext1, gnext2;                          /* Temporary variables for lattice stages */
+  uint32_t stgCnt;                               /* Temporary variables for counts */
+  q63_t acc;                                     /* Accumlator */
+  uint32_t blkCnt, tapCnt;                       /* Temporary variables for counts */
+  q15_t *px1, *px2, *pk, *pv;                    /* temporary pointers for state and coef */
+  uint32_t numStages = S->numStages;             /* number of stages */
+  q15_t *pState;                                 /* State pointer */
+  q15_t *pStateCurnt;                            /* State current pointer */
+  q15_t out;                                     /* Temporary variable for output */
+#ifdef UNALIGNED_SUPPORT_DISABLE
+  q15_t v1, v2;
+#endif
+  q31_t v;                                       /* Temporary variable for ladder coefficient */
+
+
+  blkCnt = blockSize;
+
+  pState = &S->pState[0];
+
+  /* Sample processing */
+  while(blkCnt > 0u)
+  {
+    /* Read Sample from input buffer */
+    /* fN(n) = x(n) */
+    fcurr = *pSrc++;
+
+    /* Initialize state read pointer */
+    px1 = pState;
+    /* Initialize state write pointer */
+    px2 = pState;
+    /* Set accumulator to zero */
+    acc = 0;
+    /* Initialize Ladder coeff pointer */
+    pv = &S->pvCoeffs[0];
+    /* Initialize Reflection coeff pointer */
+    pk = &S->pkCoeffs[0];
+
+
+    /* Process sample for first tap */
+    gcurr = *px1++;
+    /* fN-1(n) = fN(n) - kN * gN-1(n-1) */
+    fnext = fcurr - (((q31_t) gcurr * (*pk)) >> 15);
+    fnext = __SSAT(fnext, 16);
+    /* gN(n) = kN * fN-1(n) + gN-1(n-1) */
+    gnext = (((q31_t) fnext * (*pk++)) >> 15) + gcurr;
+    gnext = __SSAT(gnext, 16);
+    /* write gN(n) into state for next sample processing */
+    *px2++ = (q15_t) gnext;
+    /* y(n) += gN(n) * vN  */
+    acc += (q31_t) ((gnext * (*pv++)));
+
+
+    /* Update f values for next coefficient processing */
+    fcurr = fnext;
+
+    /* Loop unrolling.  Process 4 taps at a time. */
+    tapCnt = (numStages - 1u) >> 2;
+
+    while(tapCnt > 0u)
+    {
+
+      /* Process sample for 2nd, 6th ...taps */
+      /* Read gN-2(n-1) from state buffer */
+      gcurr = *px1++;
+      /* Process sample for 2nd, 6th .. taps */
+      /* fN-2(n) = fN-1(n) - kN-1 * gN-2(n-1) */
+      fnext = fcurr - (((q31_t) gcurr * (*pk)) >> 15);
+      fnext = __SSAT(fnext, 16);
+      /* gN-1(n) = kN-1 * fN-2(n) + gN-2(n-1) */
+      gnext = (((q31_t) fnext * (*pk++)) >> 15) + gcurr;
+      gnext1 = (q15_t) __SSAT(gnext, 16);
+      /* write gN-1(n) into state */
+      *px2++ = (q15_t) gnext1;
+
+
+      /* Process sample for 3nd, 7th ...taps */
+      /* Read gN-3(n-1) from state */
+      gcurr = *px1++;
+      /* Process sample for 3rd, 7th .. taps */
+      /* fN-3(n) = fN-2(n) - kN-2 * gN-3(n-1) */
+      fcurr = fnext - (((q31_t) gcurr * (*pk)) >> 15);
+      fcurr = __SSAT(fcurr, 16);
+      /* gN-2(n) = kN-2 * fN-3(n) + gN-3(n-1) */
+      gnext = (((q31_t) fcurr * (*pk++)) >> 15) + gcurr;
+      gnext2 = (q15_t) __SSAT(gnext, 16);
+      /* write gN-2(n) into state */
+      *px2++ = (q15_t) gnext2;
+
+      /* Read vN-1 and vN-2 at a time */
+#ifndef UNALIGNED_SUPPORT_DISABLE
+
+      v = *__SIMD32(pv)++;
+
+#else
+
+      v1 = *pv++;
+      v2 = *pv++;
+
+#ifndef ARM_MATH_BIG_ENDIAN
+
+      v = __PKHBT(v1, v2, 16);
+
+#else
+
+      v = __PKHBT(v2, v1, 16);
+
+#endif    /*     #ifndef ARM_MATH_BIG_ENDIAN        */
+
+#endif    /*    #ifndef UNALIGNED_SUPPORT_DISABLE */
+
+
+      /* Pack gN-1(n) and gN-2(n) */
+
+#ifndef  ARM_MATH_BIG_ENDIAN
+
+      gnext = __PKHBT(gnext1, gnext2, 16);
+
+#else
+
+      gnext = __PKHBT(gnext2, gnext1, 16);
+
+#endif /*   #ifndef  ARM_MATH_BIG_ENDIAN    */
+
+      /* y(n) += gN-1(n) * vN-1  */
+      /* process for gN-5(n) * vN-5, gN-9(n) * vN-9 ... */
+      /* y(n) += gN-2(n) * vN-2  */
+      /* process for gN-6(n) * vN-6, gN-10(n) * vN-10 ... */
+      acc = __SMLALD(gnext, v, acc);
+
+
+      /* Process sample for 4th, 8th ...taps */
+      /* Read gN-4(n-1) from state */
+      gcurr = *px1++;
+      /* Process sample for 4th, 8th .. taps */
+      /* fN-4(n) = fN-3(n) - kN-3 * gN-4(n-1) */
+      fnext = fcurr - (((q31_t) gcurr * (*pk)) >> 15);
+      fnext = __SSAT(fnext, 16);
+      /* gN-3(n) = kN-3 * fN-1(n) + gN-1(n-1) */
+      gnext = (((q31_t) fnext * (*pk++)) >> 15) + gcurr;
+      gnext1 = (q15_t) __SSAT(gnext, 16);
+      /* write  gN-3(n) for the next sample process */
+      *px2++ = (q15_t) gnext1;
+
+
+      /* Process sample for 5th, 9th ...taps */
+      /* Read gN-5(n-1) from state */
+      gcurr = *px1++;
+      /* Process sample for 5th, 9th .. taps */
+      /* fN-5(n) = fN-4(n) - kN-4 * gN-5(n-1) */
+      fcurr = fnext - (((q31_t) gcurr * (*pk)) >> 15);
+      fcurr = __SSAT(fcurr, 16);
+      /* gN-4(n) = kN-4 * fN-5(n) + gN-5(n-1) */
+      gnext = (((q31_t) fcurr * (*pk++)) >> 15) + gcurr;
+      gnext2 = (q15_t) __SSAT(gnext, 16);
+      /* write      gN-4(n) for the next sample process */
+      *px2++ = (q15_t) gnext2;
+
+      /* Read vN-3 and vN-4 at a time */
+#ifndef UNALIGNED_SUPPORT_DISABLE
+
+      v = *__SIMD32(pv)++;
+
+#else
+
+      v1 = *pv++;
+      v2 = *pv++;
+
+#ifndef ARM_MATH_BIG_ENDIAN
+
+      v = __PKHBT(v1, v2, 16);
+
+#else
+
+      v = __PKHBT(v2, v1, 16);
+
+#endif    /* #ifndef ARM_MATH_BIG_ENDIAN     */
+
+#endif    /*    #ifndef UNALIGNED_SUPPORT_DISABLE */
+
+
+      /* Pack gN-3(n) and gN-4(n) */
+#ifndef  ARM_MATH_BIG_ENDIAN
+
+      gnext = __PKHBT(gnext1, gnext2, 16);
+
+#else
+
+      gnext = __PKHBT(gnext2, gnext1, 16);
+
+#endif /*      #ifndef  ARM_MATH_BIG_ENDIAN    */
+
+      /* y(n) += gN-4(n) * vN-4  */
+      /* process for gN-8(n) * vN-8, gN-12(n) * vN-12 ... */
+      /* y(n) += gN-3(n) * vN-3  */
+      /* process for gN-7(n) * vN-7, gN-11(n) * vN-11 ... */
+      acc = __SMLALD(gnext, v, acc);
+
+      tapCnt--;
+
+    }
+
+    fnext = fcurr;
+
+    /* If the filter length is not a multiple of 4, compute the remaining filter taps */
+    tapCnt = (numStages - 1u) % 0x4u;
+
+    while(tapCnt > 0u)
+    {
+      gcurr = *px1++;
+      /* Process sample for last taps */
+      fnext = fcurr - (((q31_t) gcurr * (*pk)) >> 15);
+      fnext = __SSAT(fnext, 16);
+      gnext = (((q31_t) fnext * (*pk++)) >> 15) + gcurr;
+      gnext = __SSAT(gnext, 16);
+      /* Output samples for last taps */
+      acc += (q31_t) (((q31_t) gnext * (*pv++)));
+      *px2++ = (q15_t) gnext;
+      fcurr = fnext;
+
+      tapCnt--;
+    }
+
+    /* y(n) += g0(n) * v0 */
+    acc += (q31_t) (((q31_t) fnext * (*pv++)));
+
+    out = (q15_t) __SSAT(acc >> 15, 16);
+    *px2++ = (q15_t) fnext;
+
+    /* write out into pDst */
+    *pDst++ = out;
+
+    /* Advance the state pointer by 4 to process the next group of 4 samples */
+    pState = pState + 1u;
+    blkCnt--;
+
+  }
+
+  /* Processing is complete. Now copy last S->numStages samples to start of the buffer    
+     for the preperation of next frame process */
+  /* Points to the start of the state buffer */
+  pStateCurnt = &S->pState[0];
+  pState = &S->pState[blockSize];
+
+  stgCnt = (numStages >> 2u);
+
+  /* copy data */
+  while(stgCnt > 0u)
+  {
+#ifndef UNALIGNED_SUPPORT_DISABLE
+
+    *__SIMD32(pStateCurnt)++ = *__SIMD32(pState)++;
+    *__SIMD32(pStateCurnt)++ = *__SIMD32(pState)++;
+
+#else
+
+    *pStateCurnt++ = *pState++;
+    *pStateCurnt++ = *pState++;
+    *pStateCurnt++ = *pState++;
+    *pStateCurnt++ = *pState++;
+
+#endif /*    #ifndef UNALIGNED_SUPPORT_DISABLE */
+
+    /* Decrement the loop counter */
+    stgCnt--;
+
+  }
+
+  /* Calculation of count for remaining q15_t data */
+  stgCnt = (numStages) % 0x4u;
+
+  /* copy data */
+  while(stgCnt > 0u)
+  {
+    *pStateCurnt++ = *pState++;
+
+    /* Decrement the loop counter */
+    stgCnt--;
+  }
+
+#else
+
+  /* Run the below code for Cortex-M0 */
+
+  q31_t fcurr, fnext = 0, gcurr = 0, gnext;      /* Temporary variables for lattice stages */
+  uint32_t stgCnt;                               /* Temporary variables for counts */
+  q63_t acc;                                     /* Accumlator */
+  uint32_t blkCnt, tapCnt;                       /* Temporary variables for counts */
+  q15_t *px1, *px2, *pk, *pv;                    /* temporary pointers for state and coef */
+  uint32_t numStages = S->numStages;             /* number of stages */
+  q15_t *pState;                                 /* State pointer */
+  q15_t *pStateCurnt;                            /* State current pointer */
+  q15_t out;                                     /* Temporary variable for output */
+
+
+  blkCnt = blockSize;
+
+  pState = &S->pState[0];
+
+  /* Sample processing */
+  while(blkCnt > 0u)
+  {
+    /* Read Sample from input buffer */
+    /* fN(n) = x(n) */
+    fcurr = *pSrc++;
+
+    /* Initialize state read pointer */
+    px1 = pState;
+    /* Initialize state write pointer */
+    px2 = pState;
+    /* Set accumulator to zero */
+    acc = 0;
+    /* Initialize Ladder coeff pointer */
+    pv = &S->pvCoeffs[0];
+    /* Initialize Reflection coeff pointer */
+    pk = &S->pkCoeffs[0];
+
+    tapCnt = numStages;
+
+    while(tapCnt > 0u)
+    {
+      gcurr = *px1++;
+      /* Process sample */
+      /* fN-1(n) = fN(n) - kN * gN-1(n-1) */
+      fnext = fcurr - ((gcurr * (*pk)) >> 15);
+      fnext = __SSAT(fnext, 16);
+      /* gN(n) = kN * fN-1(n) + gN-1(n-1) */
+      gnext = ((fnext * (*pk++)) >> 15) + gcurr;
+      gnext = __SSAT(gnext, 16);
+      /* Output samples */
+      /* y(n) += gN(n) * vN */
+      acc += (q31_t) ((gnext * (*pv++)));
+      /* write gN(n) into state for next sample processing */
+      *px2++ = (q15_t) gnext;
+      /* Update f values for next coefficient processing */
+      fcurr = fnext;
+
+      tapCnt--;
+    }
+
+    /* y(n) += g0(n) * v0 */
+    acc += (q31_t) ((fnext * (*pv++)));
+
+    out = (q15_t) __SSAT(acc >> 15, 16);
+    *px2++ = (q15_t) fnext;
+
+    /* write out into pDst */
+    *pDst++ = out;
+
+    /* Advance the state pointer by 1 to process the next group of samples */
+    pState = pState + 1u;
+    blkCnt--;
+
+  }
+
+  /* Processing is complete. Now copy last S->numStages samples to start of the buffer           
+     for the preperation of next frame process */
+  /* Points to the start of the state buffer */
+  pStateCurnt = &S->pState[0];
+  pState = &S->pState[blockSize];
+
+  stgCnt = numStages;
+
+  /* copy data */
+  while(stgCnt > 0u)
+  {
+    *pStateCurnt++ = *pState++;
+
+    /* Decrement the loop counter */
+    stgCnt--;
+  }
+
+#endif /*   #ifndef ARM_MATH_CM0 */
+
+}
+
+
+
+
+/**    
+ * @} end of IIR_Lattice group    
+ */