arm_math_rpi.cpp

#if defined(RPI)

#include <stdint.h>
#include "arm_math_rpi.h"

#define __SIMD32_TYPE int32_t
#define __SIMD32(addr)        (*(__SIMD32_TYPE **) & (addr))
#define _SIMD32_OFFSET(addr)  (*(__SIMD32_TYPE *)  (addr))

#define __PKHBT(ARG1, ARG2, ARG3)      ( (((int32_t)(ARG1) <<  0) & (int32_t)0x0000FFFF) | \
                                         (((int32_t)(ARG2) << ARG3) & (int32_t)0xFFFF0000)  )


static uint32_t __SMLAD(
  uint32_t x,
  uint32_t y,
  uint32_t sum)
  {
    return ((uint32_t)(((((q31_t)x << 16) >> 16) * (((q31_t)y << 16) >> 16)) +
                       ((((q31_t)x      ) >> 16) * (((q31_t)y      ) >> 16)) +
                       ( ((q31_t)sum    )                                  )   ));
  }


  /*
   * @brief C custom defined SMLADX for M3 and M0 processors
   */

static uint32_t __SMLADX(
  uint32_t x,
  uint32_t y,
  uint32_t sum)
{
    return ((uint32_t)(((((q31_t)x << 16) >> 16) * (((q31_t)y      ) >> 16)) +
                       ((((q31_t)x      ) >> 16) * (((q31_t)y << 16) >> 16)) +
                       ( ((q31_t)sum    )                                  )   ));
}

void arm_fir_interpolate_q15(
  const arm_fir_interpolate_instance_q15 * S,
  q15_t * pSrc,
  q15_t * pDst,
  uint32_t blockSize)
{
  q15_t *pState = S->pState;                     /* State pointer                                            */
  q15_t *pCoeffs = S->pCoeffs;                   /* Coefficient pointer                                      */
  q15_t *pStateCurnt;                            /* Points to the current sample of the state                */
  q15_t *ptr1, *ptr2;                            /* Temporary pointers for state and coefficient buffers     */
  q63_t sum;                                     /* Accumulator */
  q15_t x0, c0;                                  /* Temporary variables to hold state and coefficient values */
  uint32_t i, blkCnt, tapCnt;                    /* Loop counters                                            */
  uint16_t phaseLen = S->phaseLength;            /* Length of each polyphase filter component */


  /* S->pState buffer contains previous frame (phaseLen - 1) samples */
  /* pStateCurnt points to the location where the new input data should be written */
  pStateCurnt = S->pState + (phaseLen - 1u);

  /* Total number of intput samples */
  blkCnt = blockSize;

  /* Loop over the blockSize. */
  while(blkCnt > 0u)
  {
    /* Copy new input sample into the state buffer */
    *pStateCurnt++ = *pSrc++;

    /* Loop over the Interpolation factor. */
    i = S->L;

    while(i > 0u)
    {
      /* Set accumulator to zero */
      sum = 0;

      /* Initialize state pointer */
      ptr1 = pState;

      /* Initialize coefficient pointer */
      ptr2 = pCoeffs + (i - 1u);

      /* Loop over the polyPhase length */
      tapCnt = (uint32_t) phaseLen;

      while(tapCnt > 0u)
      {
        /* Read the coefficient */
        c0 = *ptr2;

        /* Increment the coefficient pointer by interpolation factor times. */
        ptr2 += S->L;

        /* Read the input sample */
        x0 = *ptr1++;

        /* Perform the multiply-accumulate */
        sum += ((q31_t) x0 * c0);

        /* Decrement the loop counter */
        tapCnt--;
      }

      /* Store the result after converting to 1.15 format in the destination buffer */
      *pDst++ = (q15_t) (__SSAT((sum >> 15), 16));

      /* Decrement the loop counter */
      i--;
    }

    /* Advance the state pointer by 1           
     * to process the next group of interpolation factor number samples */
    pState = pState + 1;

    /* Decrement the loop counter */
    blkCnt--;
  }

  /* Processing is complete.         
   ** Now copy the last phaseLen - 1 samples to the start of the state buffer.       
   ** This prepares the state buffer for the next function call. */

  /* Points to the start of the state buffer */
  pStateCurnt = S->pState;

  i = (uint32_t) phaseLen - 1u;

  while(i > 0u)
  {
    *pStateCurnt++ = *pState++;

    /* Decrement the loop counter */
    i--;
  }

}

void arm_fir_fast_q15(
  const arm_fir_instance_q15 * S,
  q15_t * pSrc,
  q15_t * pDst,
  uint32_t blockSize)
{
  q15_t *pState = S->pState;                     /* State pointer */
  q15_t *pCoeffs = S->pCoeffs;                   /* Coefficient pointer */
  q15_t *pStateCurnt;                            /* Points to the current sample of the state */
  q31_t acc0, acc1, acc2, acc3;                  /* Accumulators */
  q15_t *pb;                                     /* Temporary pointer for coefficient buffer */
  q15_t *px;                                     /* Temporary q31 pointer for SIMD state buffer accesses */
  q31_t x0, x1, x2, c0;                          /* Temporary variables to hold SIMD state and coefficient values */
  uint32_t numTaps = S->numTaps;                 /* Number of taps in the filter */
  uint32_t tapCnt, blkCnt;                       /* Loop counters */


  /* S->pState points to state array which contains previous frame (numTaps - 1) samples */
  /* pStateCurnt points to the location where the new input data should be written */
  pStateCurnt = &(S->pState[(numTaps - 1u)]);

  /* Apply loop unrolling and compute 4 output values simultaneously.      
   * The variables acc0 ... acc3 hold output values that are being computed:      
   *      
   *    acc0 =  b[numTaps-1] * x[n-numTaps-1] + b[numTaps-2] * x[n-numTaps-2] + b[numTaps-3] * x[n-numTaps-3] +...+ b[0] * x[0]      
   *    acc1 =  b[numTaps-1] * x[n-numTaps] +   b[numTaps-2] * x[n-numTaps-1] + b[numTaps-3] * x[n-numTaps-2] +...+ b[0] * x[1]      
   *    acc2 =  b[numTaps-1] * x[n-numTaps+1] + b[numTaps-2] * x[n-numTaps] +   b[numTaps-3] * x[n-numTaps-1] +...+ b[0] * x[2]      
   *    acc3 =  b[numTaps-1] * x[n-numTaps+2] + b[numTaps-2] * x[n-numTaps+1] + b[numTaps-3] * x[n-numTaps]   +...+ b[0] * x[3]      
   */

  blkCnt = blockSize >> 2;

  /* 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)
  {
    /* Copy four new input samples into the state buffer.      
     ** Use 32-bit SIMD to move the 16-bit data.  Only requires two copies. */
    *pStateCurnt++ = *pSrc++;
    *pStateCurnt++ = *pSrc++;
    *pStateCurnt++ = *pSrc++;
    *pStateCurnt++ = *pSrc++;


    /* Set all accumulators to zero */
    acc0 = 0;
    acc1 = 0;
    acc2 = 0;
    acc3 = 0;

    /* Typecast q15_t pointer to q31_t pointer for state reading in q31_t */
    px = pState;

    /* Typecast q15_t pointer to q31_t pointer for coefficient reading in q31_t */
    pb = pCoeffs;

    /* Read the first two samples from the state buffer:  x[n-N], x[n-N-1] */
    x0 = *__SIMD32(px)++;

    /* Read the third and forth samples from the state buffer: x[n-N-2], x[n-N-3] */
    x2 = *__SIMD32(px)++;

    /* Loop over the number of taps.  Unroll by a factor of 4.      
     ** Repeat until we've computed numTaps-(numTaps%4) coefficients. */
    tapCnt = numTaps >> 2;

    while(tapCnt > 0)
    {
      /* Read the first two coefficients using SIMD:  b[N] and b[N-1] coefficients */
      c0 = *__SIMD32(pb)++;

      /* acc0 +=  b[N] * x[n-N] + b[N-1] * x[n-N-1] */
      acc0 = __SMLAD(x0, c0, acc0);

      /* acc2 +=  b[N] * x[n-N-2] + b[N-1] * x[n-N-3] */
      acc2 = __SMLAD(x2, c0, acc2);

      /* pack  x[n-N-1] and x[n-N-2] */
#ifndef ARM_MATH_BIG_ENDIAN
      x1 = __PKHBT(x2, x0, 0);
#else
      x1 = __PKHBT(x0, x2, 0);
#endif

      /* Read state x[n-N-4], x[n-N-5] */
      x0 = _SIMD32_OFFSET(px);

      /* acc1 +=  b[N] * x[n-N-1] + b[N-1] * x[n-N-2] */
      acc1 = __SMLADX(x1, c0, acc1);

      /* pack  x[n-N-3] and x[n-N-4] */
#ifndef ARM_MATH_BIG_ENDIAN
      x1 = __PKHBT(x0, x2, 0);
#else
      x1 = __PKHBT(x2, x0, 0);
#endif

      /* acc3 +=  b[N] * x[n-N-3] + b[N-1] * x[n-N-4] */
      acc3 = __SMLADX(x1, c0, acc3);

      /* Read coefficients b[N-2], b[N-3] */
      c0 = *__SIMD32(pb)++;

      /* acc0 +=  b[N-2] * x[n-N-2] + b[N-3] * x[n-N-3] */
      acc0 = __SMLAD(x2, c0, acc0);

      /* Read state x[n-N-6], x[n-N-7] with offset */
      x2 = _SIMD32_OFFSET(px + 2u);

      /* acc2 +=  b[N-2] * x[n-N-4] + b[N-3] * x[n-N-5] */
      acc2 = __SMLAD(x0, c0, acc2);

      /* acc1 +=  b[N-2] * x[n-N-3] + b[N-3] * x[n-N-4] */
      acc1 = __SMLADX(x1, c0, acc1);

      /* pack  x[n-N-5] and x[n-N-6] */
#ifndef ARM_MATH_BIG_ENDIAN
      x1 = __PKHBT(x2, x0, 0);
#else
      x1 = __PKHBT(x0, x2, 0);
#endif

      /* acc3 +=  b[N-2] * x[n-N-5] + b[N-3] * x[n-N-6] */
      acc3 = __SMLADX(x1, c0, acc3);

      /* Update state pointer for next state reading */
      px += 4u;

      /* Decrement tap count */
      tapCnt--;

    }

    /* If the filter length is not a multiple of 4, compute the remaining filter taps.       
     ** This is always be 2 taps since the filter length is even. */
    if((numTaps & 0x3u) != 0u)
    {

      /* Read last two coefficients */
      c0 = *__SIMD32(pb)++;

      /* Perform the multiply-accumulates */
      acc0 = __SMLAD(x0, c0, acc0);
      acc2 = __SMLAD(x2, c0, acc2);

      /* pack state variables */
#ifndef ARM_MATH_BIG_ENDIAN
      x1 = __PKHBT(x2, x0, 0);
#else
      x1 = __PKHBT(x0, x2, 0);
#endif

      /* Read last state variables */
      x0 = *__SIMD32(px);

      /* Perform the multiply-accumulates */
      acc1 = __SMLADX(x1, c0, acc1);

      /* pack state variables */
#ifndef ARM_MATH_BIG_ENDIAN
      x1 = __PKHBT(x0, x2, 0);
#else
      x1 = __PKHBT(x2, x0, 0);
#endif

      /* Perform the multiply-accumulates */
      acc3 = __SMLADX(x1, c0, acc3);
    }

    /* The results in the 4 accumulators are in 2.30 format.  Convert to 1.15 with saturation.       
     ** Then store the 4 outputs in the destination buffer. */

#ifndef ARM_MATH_BIG_ENDIAN

    *__SIMD32(pDst)++ =
      __PKHBT(__SSAT((acc0 >> 15), 16), __SSAT((acc1 >> 15), 16), 16);

    *__SIMD32(pDst)++ =
      __PKHBT(__SSAT((acc2 >> 15), 16), __SSAT((acc3 >> 15), 16), 16);

#else

    *__SIMD32(pDst)++ =
      __PKHBT(__SSAT((acc1 >> 15), 16), __SSAT((acc0 >> 15), 16), 16);

    *__SIMD32(pDst)++ =
      __PKHBT(__SSAT((acc3 >> 15), 16), __SSAT((acc2 >> 15), 16), 16);


#endif /*      #ifndef ARM_MATH_BIG_ENDIAN       */

    /* Advance the state pointer by 4 to process the next group of 4 samples */
    pState = pState + 4u;

    /* 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)
  {
    /* Copy two samples into state buffer */
    *pStateCurnt++ = *pSrc++;

    /* Set the accumulator to zero */
    acc0 = 0;

    /* Use SIMD to hold states and coefficients */
    px = pState;
    pb = pCoeffs;

    tapCnt = numTaps >> 1u;

    do
    {

      acc0 += (q31_t) * px++ * *pb++;
	  acc0 += (q31_t) * px++ * *pb++;

      tapCnt--;
    }
    while(tapCnt > 0u);

    /* The result is in 2.30 format.  Convert to 1.15 with saturation.      
     ** Then store the output in the destination buffer. */
    *pDst++ = (q15_t) (__SSAT((acc0 >> 15), 16));

    /* Advance state pointer by 1 for the next sample */
    pState = pState + 1u;

    /* Decrement the loop counter */
    blkCnt--;
  }

  /* Processing is complete.      
   ** Now copy the last numTaps - 1 samples to the satrt of the state buffer.      
   ** This prepares the state buffer for the next function call. */

  /* Points to the start of the state buffer */
  pStateCurnt = S->pState;

  /* Calculation of count for copying integer writes */
  tapCnt = (numTaps - 1u) >> 2;

  while(tapCnt > 0u)
  {
    *pStateCurnt++ = *pState++;
    *pStateCurnt++ = *pState++;
    *pStateCurnt++ = *pState++;
    *pStateCurnt++ = *pState++;

    tapCnt--;

  }

  /* Calculation of count for remaining q15_t data */
  tapCnt = (numTaps - 1u) % 0x4u;

  /* copy remaining data */
  while(tapCnt > 0u)
  {
    *pStateCurnt++ = *pState++;

    /* Decrement the loop counter */
    tapCnt--;
  }

}

void arm_biquad_cascade_df1_q31(
  const arm_biquad_casd_df1_inst_q31 * S,
  q31_t * pSrc,
  q31_t * pDst,
  uint32_t blockSize)
{
  q63_t acc;                                     /*  accumulator                   */
  uint32_t uShift = ((uint32_t) S->postShift + 1u);
  uint32_t lShift = 32u - uShift;                /*  Shift to be applied to the output */
  q31_t *pIn = pSrc;                             /*  input pointer initialization  */
  q31_t *pOut = pDst;                            /*  output pointer initialization */
  q31_t *pState = S->pState;                     /*  pState pointer initialization */
  q31_t *pCoeffs = S->pCoeffs;                   /*  coeff pointer initialization  */
  q31_t Xn1, Xn2, Yn1, Yn2;                      /*  Filter state variables        */
  q31_t b0, b1, b2, a1, a2;                      /*  Filter coefficients           */
  q31_t Xn;                                      /*  temporary input               */
  uint32_t sample, stage = S->numStages;         /*  loop counters                     */

 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 = (q63_t) b0 *Xn;

      /* acc +=  b1 * x[n-1] */
      acc += (q63_t) b1 *Xn1;
      /* acc +=  b[2] * x[n-2] */
      acc += (q63_t) b2 *Xn2;
      /* acc +=  a1 * y[n-1] */
      acc += (q63_t) a1 *Yn1;
      /* acc +=  a2 * y[n-2] */
      acc += (q63_t) a2 *Yn2;

      /* The result is converted to 1.31  */
      acc = acc >> lShift;

      /* 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 = (q31_t) acc;

      /* Store the output in the destination buffer. */
      *pOut++ = (q31_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);

}

void arm_q15_to_q31(
  q15_t * pSrc,
  q31_t * pDst,
  uint32_t blockSize)
{
  q15_t *pIn = pSrc;                             /* Src pointer */
  uint32_t blkCnt;                               /* loop counter */

/* Loop over blockSize number of values */
  blkCnt = blockSize;

  while(blkCnt > 0u)
  {
    /* C = (q31_t)A << 16 */
    /* convert from q15 to q31 and then store the results in the destination buffer */
    *pDst++ = (q31_t) * pIn++ << 16;

    /* Decrement the loop counter */
    blkCnt--;
  }

}

#endif