/* filter the signal using normalized lattice filter */
void WebRtcIsacfix_NormLatticeFilterAr(int16_t orderCoef,
int16_t *stateGQ0,
int32_t *lat_inQ25,
int16_t *filt_coefQ15,
int32_t *gain_lo_hiQ17,
int16_t lo_hi,
int16_t *lat_outQ0)
{
int ii,n,k,i,u;
int16_t sthQ15[MAX_AR_MODEL_ORDER];
int16_t cthQ15[MAX_AR_MODEL_ORDER];
int32_t tmp32;
int16_t tmpAR;
int16_t ARfQ0vec[HALF_SUBFRAMELEN];
int16_t ARgQ0vec[MAX_AR_MODEL_ORDER+1];
int32_t inv_gain32;
int16_t inv_gain16;
int16_t den16;
int16_t sh;
int16_t temp2,temp3;
int16_t ord_1 = orderCoef+1;
for (u=0;u<SUBFRAMES;u++)
{
int32_t temp1 = WEBRTC_SPL_MUL_16_16(u, HALF_SUBFRAMELEN);
//set the denominator and numerator of the Direct Form
temp2 = (int16_t)WEBRTC_SPL_MUL_16_16(u, orderCoef);
temp3 = (int16_t)WEBRTC_SPL_MUL_16_16(2, u) + lo_hi;
for (ii=0; ii<orderCoef; ii++) {
sthQ15[ii] = filt_coefQ15[temp2+ii];
}
WebRtcSpl_SqrtOfOneMinusXSquared(sthQ15, orderCoef, cthQ15);
/* Simulation of the 25 files shows that maximum value in
the vector gain_lo_hiQ17[] is 441344, which means that
it is log2((2^31)/441344) = 12.2 shifting bits from
saturation. Therefore, it should be safe to use Q27 instead
of Q17. */
tmp32 = WEBRTC_SPL_LSHIFT_W32(gain_lo_hiQ17[temp3], 10); // Q27
for (k=0;k<orderCoef;k++) {
tmp32 = WEBRTC_SPL_MUL_16_32_RSFT15(cthQ15[k], tmp32); // Q15*Q27>>15 = Q27
}
sh = WebRtcSpl_NormW32(tmp32); // tmp32 is the gain
den16 = (int16_t) WEBRTC_SPL_SHIFT_W32(tmp32, sh-16); //Q(27+sh-16) = Q(sh+11) (all 16 bits are value bits)
inv_gain32 = WebRtcSpl_DivW32W16((int32_t)2147483647, den16); // 1/gain in Q31/Q(sh+11) = Q(20-sh)
//initial conditions
inv_gain16 = (int16_t)(inv_gain32 >> 2); // 1/gain in Q(20-sh-2) = Q(18-sh)
for (i=0;i<HALF_SUBFRAMELEN;i++)
{
tmp32 = WEBRTC_SPL_LSHIFT_W32(lat_inQ25[i + temp1], 1); //Q25->Q26
tmp32 = WEBRTC_SPL_MUL_16_32_RSFT16(inv_gain16, tmp32); //lat_in[]*inv_gain in (Q(18-sh)*Q26)>>16 = Q(28-sh)
tmp32 = WEBRTC_SPL_SHIFT_W32(tmp32, -(28-sh)); // lat_in[]*inv_gain in Q0
ARfQ0vec[i] = (int16_t)WebRtcSpl_SatW32ToW16(tmp32); // Q0
}
for (i=orderCoef-1;i>=0;i--) //get the state of f&g for the first input, for all orders
{
tmp32 = (cthQ15[i] * ARfQ0vec[0] - sthQ15[i] * stateGQ0[i] + 16384) >> 15;
tmpAR = (int16_t)WebRtcSpl_SatW32ToW16(tmp32); // Q0
tmp32 = (sthQ15[i] * ARfQ0vec[0] + cthQ15[i] * stateGQ0[i] + 16384) >> 15;
ARgQ0vec[i+1] = (int16_t)WebRtcSpl_SatW32ToW16(tmp32); // Q0
ARfQ0vec[0] = tmpAR;
}
ARgQ0vec[0] = ARfQ0vec[0];
// Filter ARgQ0vec[] and ARfQ0vec[] through coefficients cthQ15[] and sthQ15[].
WebRtcIsacfix_FilterArLoop(ARgQ0vec, ARfQ0vec, cthQ15, sthQ15, orderCoef);
for(n=0;n<HALF_SUBFRAMELEN;n++)
{
lat_outQ0[n + temp1] = ARfQ0vec[n];
}
/* cannot use memcpy in the following */
for (i=0;i<ord_1;i++)
{
stateGQ0[i] = ARgQ0vec[i];
}
}
return;
}
/* filter the signal using normalized lattice filter */
void WebRtcIsacfix_NormLatticeFilterAr(size_t orderCoef,
int16_t *stateGQ0,
int32_t *lat_inQ25,
int16_t *filt_coefQ15,
int32_t *gain_lo_hiQ17,
int16_t lo_hi,
int16_t *lat_outQ0)
{
size_t ii, k, i;
int n, u;
int16_t sthQ15[MAX_AR_MODEL_ORDER];
int16_t cthQ15[MAX_AR_MODEL_ORDER];
int32_t tmp32;
int16_t tmpAR;
int16_t ARfQ0vec[HALF_SUBFRAMELEN];
int16_t ARgQ0vec[MAX_AR_MODEL_ORDER+1];
int32_t inv_gain32;
int16_t inv_gain16;
int16_t den16;
int16_t sh;
int16_t temp2,temp3;
size_t ord_1 = orderCoef+1;
for (u=0;u<SUBFRAMES;u++)
{
int32_t temp1 = u * HALF_SUBFRAMELEN;
//set the denominator and numerator of the Direct Form
temp2 = (int16_t)(u * orderCoef);
temp3 = (int16_t)(2 * u + lo_hi);
for (ii=0; ii<orderCoef; ii++) {
sthQ15[ii] = filt_coefQ15[temp2+ii];
}
WebRtcSpl_SqrtOfOneMinusXSquared(sthQ15, orderCoef, cthQ15);
// Originally, this line was assumed to never overflow, since "[s]imulation
// of the 25 files shows that maximum value in the vector gain_lo_hiQ17[]
// is 441344, which means that it is log2((2^31)/441344) = 12.2 shifting
// bits from saturation. Therefore, it should be safe to use Q27 instead of
// Q17." However, a fuzzer test succeeded in provoking an overflow here,
// which we ignore on the theory that only "abnormal" inputs cause
// overflow.
tmp32 = OverflowingLShiftS32(gain_lo_hiQ17[temp3], 10); // Q27
for (k=0;k<orderCoef;k++) {
tmp32 = WEBRTC_SPL_MUL_16_32_RSFT15(cthQ15[k], tmp32); // Q15*Q27>>15 = Q27
}
sh = WebRtcSpl_NormW32(tmp32); // tmp32 is the gain
den16 = (int16_t) WEBRTC_SPL_SHIFT_W32(tmp32, sh-16); //Q(27+sh-16) = Q(sh+11) (all 16 bits are value bits)
inv_gain32 = WebRtcSpl_DivW32W16((int32_t)2147483647, den16); // 1/gain in Q31/Q(sh+11) = Q(20-sh)
//initial conditions
inv_gain16 = (int16_t)(inv_gain32 >> 2); // 1/gain in Q(20-sh-2) = Q(18-sh)
for (i=0;i<HALF_SUBFRAMELEN;i++)
{
tmp32 = OverflowingLShiftS32(lat_inQ25[i + temp1], 1); // Q25->Q26
tmp32 = WEBRTC_SPL_MUL_16_32_RSFT16(inv_gain16, tmp32); //lat_in[]*inv_gain in (Q(18-sh)*Q26)>>16 = Q(28-sh)
tmp32 = WEBRTC_SPL_SHIFT_W32(tmp32, -(28-sh)); // lat_in[]*inv_gain in Q0
ARfQ0vec[i] = (int16_t)WebRtcSpl_SatW32ToW16(tmp32); // Q0
}
// Get the state of f & g for the first input, for all orders.
for (i = orderCoef; i > 0; i--)
{
tmp32 = (cthQ15[i - 1] * ARfQ0vec[0] - sthQ15[i - 1] * stateGQ0[i - 1] +
16384) >> 15;
tmpAR = (int16_t)WebRtcSpl_SatW32ToW16(tmp32); // Q0
tmp32 = (sthQ15[i - 1] * ARfQ0vec[0] + cthQ15[i - 1] * stateGQ0[i - 1] +
16384) >> 15;
ARgQ0vec[i] = (int16_t)WebRtcSpl_SatW32ToW16(tmp32); // Q0
ARfQ0vec[0] = tmpAR;
}
ARgQ0vec[0] = ARfQ0vec[0];
// Filter ARgQ0vec[] and ARfQ0vec[] through coefficients cthQ15[] and sthQ15[].
WebRtcIsacfix_FilterArLoop(ARgQ0vec, ARfQ0vec, cthQ15, sthQ15, orderCoef);
for(n=0;n<HALF_SUBFRAMELEN;n++)
{
lat_outQ0[n + temp1] = ARfQ0vec[n];
}
/* cannot use memcpy in the following */
for (i=0;i<ord_1;i++)
{
stateGQ0[i] = ARgQ0vec[i];
}
}
return;
}
