/**
* @brief Core Real IFFT process
* @param[in] *pSrc points to the input buffer.
* @param[in] fftLen length of FFT.
* @param[in] *pATable points to the twiddle Coef A buffer.
* @param[in] *pBTable points to the twiddle Coef B buffer.
* @param[out] *pDst points to the output buffer.
* @param[in] modifier twiddle coefficient modifier that supports different size FFTs with the same twiddle factor table.
* @return none.
*/
void arm_split_rifft_q31(
q31_t * pSrc,
uint32_t fftLen,
q31_t * pATable,
q31_t * pBTable,
q31_t * pDst,
uint32_t modifier)
{
q31_t outR, outI; /* Temporary variables for output */
q31_t *pCoefA, *pCoefB; /* Temporary pointers for twiddle factors */
q31_t CoefA1, CoefA2, CoefB1; /* Temporary variables for twiddle coefficients */
q31_t *pIn1 = &pSrc[0], *pIn2 = &pSrc[(2u * fftLen) + 1u];
pCoefA = &pATable[0];
pCoefB = &pBTable[0];
while(fftLen > 0u)
{
/*
outR = (pIn[2 * i] * pATable[2 * i] + pIn[2 * i + 1] * pATable[2 * i + 1] +
pIn[2 * n - 2 * i] * pBTable[2 * i] -
pIn[2 * n - 2 * i + 1] * pBTable[2 * i + 1]);
outI = (pIn[2 * i + 1] * pATable[2 * i] - pIn[2 * i] * pATable[2 * i + 1] -
pIn[2 * n - 2 * i] * pBTable[2 * i + 1] -
pIn[2 * n - 2 * i + 1] * pBTable[2 * i]);
*/
CoefA1 = *pCoefA++;
CoefA2 = *pCoefA;
/* outR = (pIn[2 * i] * pATable[2 * i] */
mult_32x32_keep32_R(outR, *pIn1, CoefA1);
/* - pIn[2 * i] * pATable[2 * i + 1] */
mult_32x32_keep32_R(outI, *pIn1++, -CoefA2);
/* pIn[2 * i + 1] * pATable[2 * i + 1] */
multAcc_32x32_keep32_R(outR, *pIn1, CoefA2);
/* pIn[2 * i + 1] * pATable[2 * i] */
multAcc_32x32_keep32_R(outI, *pIn1++, CoefA1);
/* pIn[2 * n - 2 * i] * pBTable[2 * i] */
multAcc_32x32_keep32_R(outR, *pIn2, CoefA2);
CoefB1 = *pCoefB;
/* pIn[2 * n - 2 * i] * pBTable[2 * i + 1] */
multSub_32x32_keep32_R(outI, *pIn2--, CoefB1);
/* pIn[2 * n - 2 * i + 1] * pBTable[2 * i + 1] */
multAcc_32x32_keep32_R(outR, *pIn2, CoefB1);
/* pIn[2 * n - 2 * i + 1] * pBTable[2 * i] */
multAcc_32x32_keep32_R(outI, *pIn2--, CoefA2);
/* write output */
*pDst++ = outR;
*pDst++ = outI;
/* update coefficient pointer */
pCoefB = pCoefB + (modifier * 2u);
pCoefA = pCoefA + ((modifier * 2u) - 1u);
/* Decrement loop count */
fftLen--;
}
}
void arm_biquad_cascade_df1_fast_q31(
const arm_biquad_casd_df1_inst_q31 * S,
q31_t * pSrc,
q31_t * pDst,
uint32_t blockSize)
{
q31_t acc = 0; /* accumulator */
q31_t Xn1, Xn2, Yn1, Yn2; /* Filter state variables */
q31_t b0, b1, b2, a1, a2; /* Filter coefficients */
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 Xn; /* temporary input */
int32_t shift = (int32_t) S->postShift + 1; /* Shift to be applied to the output */
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];
/* Apply loop unrolling and compute 4 output values simultaneously. */
/* The variables acc ... acc3 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]
*/
sample = 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(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) (((q63_t) b1 * Xn1) >> 32);*/
mult_32x32_keep32_R(acc, b1, Xn1);
/* acc += b1 * x[n-1] */
/*acc = (q31_t) ((((q63_t) acc << 32) + ((q63_t) b0 * (Xn))) >> 32);*/
multAcc_32x32_keep32_R(acc, b0, Xn);
/* acc += b[2] * x[n-2] */
/*acc = (q31_t) ((((q63_t) acc << 32) + ((q63_t) b2 * (Xn2))) >> 32);*/
multAcc_32x32_keep32_R(acc, b2, Xn2);
/* acc += a1 * y[n-1] */
/*acc = (q31_t) ((((q63_t) acc << 32) + ((q63_t) a1 * (Yn1))) >> 32);*/
multAcc_32x32_keep32_R(acc, a1, Yn1);
/* acc += a2 * y[n-2] */
/*acc = (q31_t) ((((q63_t) acc << 32) + ((q63_t) a2 * (Yn2))) >> 32);*/
multAcc_32x32_keep32_R(acc, a2, Yn2);
/* The result is converted to 1.31 , Yn2 variable is reused */
Yn2 = acc << shift;
/* Read the second input */
Xn2 = *(pIn + 1u);
/* Store the output in the destination buffer. */
*pOut = Yn2;
/* 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) (((q63_t) b0 * (Xn2)) >> 32);*/
mult_32x32_keep32_R(acc, b0, Xn2);
/* acc += b1 * x[n-1] */
/*acc = (q31_t) ((((q63_t) acc << 32) + ((q63_t) b1 * (Xn))) >> 32);*/
multAcc_32x32_keep32_R(acc, b1, Xn);
/* acc += b[2] * x[n-2] */
/*acc = (q31_t) ((((q63_t) acc << 32) + ((q63_t) b2 * (Xn1))) >> 32);*/
multAcc_32x32_keep32_R(acc, b2, Xn1);
/* acc += a1 * y[n-1] */
/*acc = (q31_t) ((((q63_t) acc << 32) + ((q63_t) a1 * (Yn2))) >> 32);*/
multAcc_32x32_keep32_R(acc, a1, Yn2);
/* acc += a2 * y[n-2] */
/*acc = (q31_t) ((((q63_t) acc << 32) + ((q63_t) a2 * (Yn1))) >> 32);*/
multAcc_32x32_keep32_R(acc, a2, Yn1);
/* The result is converted to 1.31, Yn1 variable is reused */
Yn1 = acc << shift;
/* Read the third input */
Xn1 = *(pIn + 2u);
/* Store the output in the destination buffer. */
*(pOut + 1u) = Yn1;
/* 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) (((q63_t) b0 * (Xn1)) >> 32);*/
mult_32x32_keep32_R(acc, b0, Xn1);
/* acc += b1 * x[n-1] */
/*acc = (q31_t) ((((q63_t) acc << 32) + ((q63_t) b1 * (Xn2))) >> 32);*/
multAcc_32x32_keep32_R(acc, b1, Xn2);
/* acc += b[2] * x[n-2] */
/*acc = (q31_t) ((((q63_t) acc << 32) + ((q63_t) b2 * (Xn))) >> 32);*/
multAcc_32x32_keep32_R(acc, b2, Xn);
/* acc += a1 * y[n-1] */
/*acc = (q31_t) ((((q63_t) acc << 32) + ((q63_t) a1 * (Yn1))) >> 32);*/
multAcc_32x32_keep32_R(acc, a1, Yn1);
/* acc += a2 * y[n-2] */
/*acc = (q31_t) ((((q63_t) acc << 32) + ((q63_t) a2 * (Yn2))) >> 32);*/
multAcc_32x32_keep32_R(acc, a2, Yn2);
/* The result is converted to 1.31, Yn2 variable is reused */
Yn2 = acc << shift;
/* Read the forth input */
Xn = *(pIn + 3u);
/* Store the output in the destination buffer. */
*(pOut + 2u) = Yn2;
pIn += 4u;
/* 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) (((q63_t) b0 * (Xn)) >> 32);*/
mult_32x32_keep32_R(acc, b0, Xn);
/* acc += b1 * x[n-1] */
/*acc = (q31_t) ((((q63_t) acc << 32) + ((q63_t) b1 * (Xn1))) >> 32);*/
multAcc_32x32_keep32_R(acc, b1, Xn1);
/* acc += b[2] * x[n-2] */
/*acc = (q31_t) ((((q63_t) acc << 32) + ((q63_t) b2 * (Xn2))) >> 32);*/
multAcc_32x32_keep32_R(acc, b2, Xn2);
/* acc += a1 * y[n-1] */
/*acc = (q31_t) ((((q63_t) acc << 32) + ((q63_t) a1 * (Yn2))) >> 32);*/
multAcc_32x32_keep32_R(acc, a1, Yn2);
/* acc += a2 * y[n-2] */
/*acc = (q31_t) ((((q63_t) acc << 32) + ((q63_t) a2 * (Yn1))) >> 32);*/
multAcc_32x32_keep32_R(acc, a2, Yn1);
/* Every time after the output is computed state should be updated. */
/* The states should be updated as: */
/* Xn2 = Xn1 */
Xn2 = Xn1;
/* The result is converted to 1.31, Yn1 variable is reused */
Yn1 = acc << shift;
/* Xn1 = Xn */
Xn1 = Xn;
/* Store the output in the destination buffer. */
*(pOut + 3u) = Yn1;
pOut += 4u;
/* decrement the loop counter */
sample--;
}
/* If the blockSize is not a multiple of 4, compute any remaining output samples here.
** No loop unrolling is used. */
sample = (blockSize & 0x3u);
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) (((q63_t) b0 * (Xn)) >> 32);*/
mult_32x32_keep32_R(acc, b0, Xn);
/* acc += b1 * x[n-1] */
/*acc = (q31_t) ((((q63_t) acc << 32) + ((q63_t) b1 * (Xn1))) >> 32);*/
multAcc_32x32_keep32_R(acc, b1, Xn1);
/* acc += b[2] * x[n-2] */
/*acc = (q31_t) ((((q63_t) acc << 32) + ((q63_t) b2 * (Xn2))) >> 32);*/
multAcc_32x32_keep32_R(acc, b2, Xn2);
/* acc += a1 * y[n-1] */
/*acc = (q31_t) ((((q63_t) acc << 32) + ((q63_t) a1 * (Yn1))) >> 32);*/
multAcc_32x32_keep32_R(acc, a1, Yn1);
/* acc += a2 * y[n-2] */
/*acc = (q31_t) ((((q63_t) acc << 32) + ((q63_t) a2 * (Yn2))) >> 32);*/
multAcc_32x32_keep32_R(acc, a2, Yn2);
/* The result is converted to 1.31 */
acc = acc << shift;
/* 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 = acc;
/* Store the output in the destination buffer. */
*pOut++ = 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);
}
/**
* @brief Core Real FFT process
* @param[in] *pSrc points to the input buffer.
* @param[in] fftLen length of FFT.
* @param[in] *pATable points to the twiddle Coef A buffer.
* @param[in] *pBTable points to the twiddle Coef B buffer.
* @param[out] *pDst points to the output buffer.
* @param[in] modifier twiddle coefficient modifier that supports different size FFTs with the same twiddle factor table.
* @return none.
*/
void arm_split_rfft_q31(
q31_t * pSrc,
uint32_t fftLen,
q31_t * pATable,
q31_t * pBTable,
q31_t * pDst,
uint32_t modifier)
{
uint32_t i; /* Loop Counter */
q31_t outR, outI; /* Temporary variables for output */
q31_t *pCoefA, *pCoefB; /* Temporary pointers for twiddle factors */
q31_t CoefA1, CoefA2, CoefB1; /* Temporary variables for twiddle coefficients */
q31_t *pOut1 = &pDst[2], *pOut2 = &pDst[(4u * fftLen) - 1u];
q31_t *pIn1 = &pSrc[2], *pIn2 = &pSrc[(2u * fftLen) - 1u];
/* Init coefficient pointers */
pCoefA = &pATable[modifier * 2u];
pCoefB = &pBTable[modifier * 2u];
i = fftLen - 1u;
while(i > 0u)
{
/*
outR = (pSrc[2 * i] * pATable[2 * i] - pSrc[2 * i + 1] * pATable[2 * i + 1]
+ pSrc[2 * n - 2 * i] * pBTable[2 * i] +
pSrc[2 * n - 2 * i + 1] * pBTable[2 * i + 1]);
*/
/* outI = (pIn[2 * i + 1] * pATable[2 * i] + pIn[2 * i] * pATable[2 * i + 1] +
pIn[2 * n - 2 * i] * pBTable[2 * i + 1] -
pIn[2 * n - 2 * i + 1] * pBTable[2 * i]); */
CoefA1 = *pCoefA++;
CoefA2 = *pCoefA;
/* outR = (pSrc[2 * i] * pATable[2 * i] */
mult_32x32_keep32_R(outR, *pIn1, CoefA1);
/* outI = pIn[2 * i] * pATable[2 * i + 1] */
mult_32x32_keep32_R(outI, *pIn1++, CoefA2);
/* - pSrc[2 * i + 1] * pATable[2 * i + 1] */
multSub_32x32_keep32_R(outR, *pIn1, CoefA2);
/* (pIn[2 * i + 1] * pATable[2 * i] */
multAcc_32x32_keep32_R(outI, *pIn1++, CoefA1);
/* pSrc[2 * n - 2 * i] * pBTable[2 * i] */
multSub_32x32_keep32_R(outR, *pIn2, CoefA2);
CoefB1 = *pCoefB;
/* pIn[2 * n - 2 * i] * pBTable[2 * i + 1] */
multSub_32x32_keep32_R(outI, *pIn2--, CoefB1);
/* pSrc[2 * n - 2 * i + 1] * pBTable[2 * i + 1] */
multAcc_32x32_keep32_R(outR, *pIn2, CoefB1);
/* pIn[2 * n - 2 * i + 1] * pBTable[2 * i] */
multSub_32x32_keep32_R(outI, *pIn2--, CoefA2);
/* write output */
*pOut1++ = outR;
*pOut1++ = outI;
/* write complex conjugate output */
*pOut2-- = -outI;
*pOut2-- = outR;
/* update coefficient pointer */
pCoefB = pCoefB + (modifier * 2u);
pCoefA = pCoefA + ((modifier * 2u) - 1u);
i--;
}
pDst[2u * fftLen] = (pSrc[0] - pSrc[1]) >> 1;
pDst[(2u * fftLen) + 1u] = 0;
pDst[0] = (pSrc[0] + pSrc[1]) >> 1;
pDst[1] = 0;
}
