diff options
Diffstat (limited to 'fw/cdc-dials/Drivers/CMSIS/DSP/DSP_Lib_TestSuite/RefLibs/src/FilteringFunctions/biquad.c')
| -rw-r--r-- | fw/cdc-dials/Drivers/CMSIS/DSP/DSP_Lib_TestSuite/RefLibs/src/FilteringFunctions/biquad.c | 713 |
1 files changed, 713 insertions, 0 deletions
diff --git a/fw/cdc-dials/Drivers/CMSIS/DSP/DSP_Lib_TestSuite/RefLibs/src/FilteringFunctions/biquad.c b/fw/cdc-dials/Drivers/CMSIS/DSP/DSP_Lib_TestSuite/RefLibs/src/FilteringFunctions/biquad.c new file mode 100644 index 0000000..1fe7c54 --- /dev/null +++ b/fw/cdc-dials/Drivers/CMSIS/DSP/DSP_Lib_TestSuite/RefLibs/src/FilteringFunctions/biquad.c @@ -0,0 +1,713 @@ +#include "ref.h"
+
+void ref_biquad_cascade_df2T_f32(
+ const arm_biquad_cascade_df2T_instance_f32 * S,
+ float32_t * pSrc,
+ float32_t * pDst,
+ uint32_t blockSize)
+{
+ float32_t *pIn = pSrc; /* source pointer */
+ float32_t *pOut = pDst; /* destination pointer */
+ float32_t *pState = S->pState; /* State pointer */
+ float32_t *pCoeffs = S->pCoeffs; /* coefficient pointer */
+ float32_t acc; /* accumulator */
+ float32_t b0, b1, b2, a1, a2; /* Filter coefficients */
+ float32_t Xn; /* temporary input */
+ float32_t d1, d2; /* state variables */
+ 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 */
+ d1 = pState[0];
+ d2 = pState[1];
+
+ sample = blockSize;
+
+ while (sample > 0U)
+ {
+ /* Read the input */
+ Xn = *pIn++;
+
+ /* y[n] = b0 * x[n] + d1 */
+ acc = (b0 * Xn) + d1;
+
+ /* Store the result in the accumulator in the destination buffer. */
+ *pOut++ = acc;
+
+ /* Every time after the output is computed state should be updated. */
+ /* d1 = b1 * x[n] + a1 * y[n] + d2 */
+ d1 = (b1 * Xn + a1 * acc) + d2;
+
+ /* d2 = b2 * x[n] + a2 * y[n] */
+ d2 = (b2 * Xn) + (a2 * acc);
+
+ /* decrement the loop counter */
+ sample--;
+ }
+
+ /* Store the updated state variables back into the state array */
+ *pState++ = d1;
+ *pState++ = d2;
+
+ /* The current stage input is given as the output to the next stage */
+ pIn = pDst;
+
+ /*Reset the output working pointer */
+ pOut = pDst;
+
+ /* decrement the loop counter */
+ stage--;
+
+ } while (stage > 0U);
+}
+
+
+void ref_biquad_cascade_stereo_df2T_f32(
+ const arm_biquad_cascade_stereo_df2T_instance_f32 * S,
+ float32_t * pSrc,
+ float32_t * pDst,
+ uint32_t blockSize)
+{
+ float32_t *pIn = pSrc; /* source pointer */
+ float32_t *pOut = pDst; /* destination pointer */
+ float32_t *pState = S->pState; /* State pointer */
+ float32_t *pCoeffs = S->pCoeffs; /* coefficient pointer */
+ float32_t acc1a, acc1b; /* accumulator */
+ float32_t b0, b1, b2, a1, a2; /* Filter coefficients */
+ float32_t Xn1a, Xn1b; /* temporary input */
+ float32_t d1a, d2a, d1b, d2b; /* state variables */
+ 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 */
+ d1a = pState[0];
+ d2a = pState[1];
+ d1b = pState[2];
+ d2b = pState[3];
+
+ sample = blockSize;
+
+ while (sample > 0U)
+ {
+ /* Read the input */
+ Xn1a = *pIn++; //Channel a
+ Xn1b = *pIn++; //Channel b
+
+ /* y[n] = b0 * x[n] + d1 */
+ acc1a = (b0 * Xn1a) + d1a;
+ acc1b = (b0 * Xn1b) + d1b;
+
+ /* Store the result in the accumulator in the destination buffer. */
+ *pOut++ = acc1a;
+ *pOut++ = acc1b;
+
+ /* Every time after the output is computed state should be updated. */
+ /* d1 = b1 * x[n] + a1 * y[n] + d2 */
+ d1a = ((b1 * Xn1a) + (a1 * acc1a)) + d2a;
+ d1b = ((b1 * Xn1b) + (a1 * acc1b)) + d2b;
+
+ /* d2 = b2 * x[n] + a2 * y[n] */
+ d2a = (b2 * Xn1a) + (a2 * acc1a);
+ d2b = (b2 * Xn1b) + (a2 * acc1b);
+
+ /* decrement the loop counter */
+ sample--;
+ }
+
+ /* Store the updated state variables back into the state array */
+ *pState++ = d1a;
+ *pState++ = d2a;
+ *pState++ = d1b;
+ *pState++ = d2b;
+
+ /* The current stage input is given as the output to the next stage */
+ pIn = pDst;
+
+ /*Reset the output working pointer */
+ pOut = pDst;
+
+ /* decrement the loop counter */
+ stage--;
+
+ } while (stage > 0U);
+
+}
+
+void ref_biquad_cascade_df2T_f64(
+ const arm_biquad_cascade_df2T_instance_f64 * S,
+ float64_t * pSrc,
+ float64_t * pDst,
+ uint32_t blockSize)
+{
+ float64_t *pIn = pSrc; /* source pointer */
+ float64_t *pOut = pDst; /* destination pointer */
+ float64_t *pState = S->pState; /* State pointer */
+ float64_t *pCoeffs = S->pCoeffs; /* coefficient pointer */
+ float64_t acc; /* accumulator */
+ float64_t b0, b1, b2, a1, a2; /* Filter coefficients */
+ float64_t Xn; /* temporary input */
+ float64_t d1, d2; /* state variables */
+ 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 */
+ d1 = pState[0];
+ d2 = pState[1];
+
+ sample = blockSize;
+
+ while (sample > 0U)
+ {
+ /* Read the input */
+ Xn = *pIn++;
+
+ /* y[n] = b0 * x[n] + d1 */
+ acc = (b0 * Xn) + d1;
+
+ /* Store the result in the accumulator in the destination buffer. */
+ *pOut++ = acc;
+
+ /* Every time after the output is computed state should be updated. */
+ /* d1 = b1 * x[n] + a1 * y[n] + d2 */
+ d1 = (b1 * Xn + a1 * acc) + d2;
+
+ /* d2 = b2 * x[n] + a2 * y[n] */
+ d2 = (b2 * Xn) + (a2 * acc);
+
+ /* decrement the loop counter */
+ sample--;
+ }
+
+ /* Store the updated state variables back into the state array */
+ *pState++ = d1;
+ *pState++ = d2;
+
+ /* The current stage input is given as the output to the next stage */
+ pIn = pDst;
+
+ /*Reset the output working pointer */
+ pOut = pDst;
+
+ /* decrement the loop counter */
+ stage--;
+
+ } while (stage > 0U);
+}
+
+void ref_biquad_cascade_df1_f32(
+ const arm_biquad_casd_df1_inst_f32 * S,
+ float32_t * pSrc,
+ float32_t * pDst,
+ uint32_t blockSize)
+{
+ float32_t *pIn = pSrc; /* source pointer */
+ float32_t *pOut = pDst; /* destination pointer */
+ float32_t *pState = S->pState; /* pState pointer */
+ float32_t *pCoeffs = S->pCoeffs; /* coefficient pointer */
+ float32_t acc; /* Simulates the accumulator */
+ float32_t b0, b1, b2, a1, a2; /* Filter coefficients */
+ float32_t Xn1, Xn2, Yn1, Yn2; /* Filter pState variables */
+ float32_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 pState 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 * Xn) + (b1 * Xn1) + (b2 * Xn2) + (a1 * Yn1) + (a2 * Yn2);
+
+ /* Store the result in the accumulator in the destination buffer. */
+ *pOut++ = acc;
+
+ /* 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;
+
+ /* decrement the loop counter */
+ sample--;
+ }
+
+ /* Store the updated state variables back into the pState array */
+ *pState++ = Xn1;
+ *pState++ = Xn2;
+ *pState++ = Yn1;
+ *pState++ = Yn2;
+
+ /* The first stage goes from the input buffer to the output buffer. */
+ /* Subsequent numStages occur in-place in the output buffer */
+ pIn = pDst;
+
+ /* Reset the output pointer */
+ pOut = pDst;
+
+ /* decrement the loop counter */
+ stage--;
+
+ } while (stage > 0U);
+}
+
+void ref_biquad_cas_df1_32x64_q31(
+ const arm_biquad_cas_df1_32x64_ins_q31 * S,
+ q31_t * pSrc,
+ q31_t * pDst,
+ uint32_t blockSize)
+{
+ q31_t *pIn = pSrc; /* input pointer initialization */
+ q31_t *pOut = pDst; /* output pointer initialization */
+ q63_t *pState = S->pState; /* state pointer initialization */
+ q31_t *pCoeffs = S->pCoeffs; /* coeff pointer initialization */
+ q63_t acc; /* accumulator */
+ q31_t Xn1, Xn2; /* Input Filter state variables */
+ q63_t Yn1, Yn2; /* Output Filter state variables */
+ q31_t b0, b1, b2, a1, a2; /* Filter coefficients */
+ 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 */
+ q31_t acc_l, acc_h; /* temporary output */
+ uint32_t uShift = ((uint32_t) S->postShift + 1U);
+ uint32_t lShift = 32U - uShift; /* Shift to be applied to the output */
+
+ 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];
+
+ 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 = (q63_t)Xn*b0 + (q63_t)Xn1*b1 + (q63_t)Xn2*b2;
+ /* acc += a1 * y[n-1] */
+ acc += mult32x64(Yn1, a1);
+ /* acc += a2 * y[n-2] */
+ acc += mult32x64(Yn2, a2);
+
+ /* Every time after the output is computed state should be updated. */
+ Xn2 = Xn1;
+ Xn1 = Xn;
+ Yn2 = Yn1;
+
+ /* The result is converted to 1.63, Yn1 variable is reused */
+ Yn1 = acc << shift;
+
+ /* 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 */
+ acc_h = (uint32_t) acc_l >> lShift | acc_h << uShift;
+
+ /* Store the output in the destination buffer in 1.31 format. */
+ *pOut++ = acc_h;
+
+ /* decrement the loop counter */
+ sample--;
+ }
+
+ /* The first stage output is given as input to the second stage. */
+ pIn = pDst;
+
+ /* Reset to destination buffer working pointer */
+ pOut = pDst;
+
+ /* Store the updated state variables back into the pState array */
+ *pState++ = (q63_t) Xn1;
+ *pState++ = (q63_t) Xn2;
+ *pState++ = Yn1;
+ *pState++ = Yn2;
+
+ } while (--stage);
+}
+
+void ref_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 ref_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];
+
+ 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] */
+ mult_32x32_keep32_R(acc, b0, Xn);
+ multAcc_32x32_keep32_R(acc, b1, Xn1);
+ multAcc_32x32_keep32_R(acc, b2, Xn2);
+ multAcc_32x32_keep32_R(acc, a1, Yn1);
+ multAcc_32x32_keep32_R(acc, a2, Yn2);
+
+ /* The result is converted to 1.31 */
+ acc <<= shift;
+
+ /* Every time after the output is computed state should be updated. */
+ 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);
+}
+
+void ref_biquad_cascade_df1_fast_q15(
+ const arm_biquad_casd_df1_inst_q15 * S,
+ q15_t * pSrc,
+ q15_t * pDst,
+ uint32_t blockSize)
+{
+ 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 */
+ q31_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++;
+ pCoeffs++; // skip the 0 coefficient
+ b1 = *pCoeffs++;
+ b2 = *pCoeffs++;
+ a1 = *pCoeffs++;
+ a2 = *pCoeffs++;
+
+ /* Reading the state values */
+ Xn1 = pState[0];
+ Xn2 = pState[1];
+ Yn1 = pState[2];
+ Yn2 = pState[3];
+
+ 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 = (q31_t)b0*Xn + (q31_t)b1*Xn1 + (q31_t)b2*Xn2 + (q31_t)a1*Yn1 + (q31_t)a2*Yn2;
+
+ /* The result is converted to 1.15 */
+ acc = ref_sat_q15(acc >> shift);
+
+ /* Every time after the output is computed state should be updated. */
+ 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);
+}
+
+void ref_biquad_cascade_df1_q15(
+ const arm_biquad_casd_df1_inst_q15 * S,
+ q15_t * pSrc,
+ q15_t * pDst,
+ uint32_t blockSize)
+{
+ 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++;
+ pCoeffs++; // skip the 0 coefficient
+ b1 = *pCoeffs++;
+ b2 = *pCoeffs++;
+ a1 = *pCoeffs++;
+ a2 = *pCoeffs++;
+
+ /* Reading the state values */
+ Xn1 = pState[0];
+ Xn2 = pState[1];
+ Yn1 = pState[2];
+ Yn2 = pState[3];
+
+ 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 = (q31_t)b0*Xn + (q31_t)b1*Xn1 + (q31_t)b2*Xn2 + (q31_t)a1*Yn1 + (q31_t)a2*Yn2;
+
+ /* The result is converted to 1.15 */
+ acc = ref_sat_q15(acc >> shift);
+
+ /* Every time after the output is computed state should be updated. */
+ 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);
+}
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