// Given an input sample, this function mixes echo into the four-channel late
// reverb.
static __inline ALvoid EAXEcho(ALverbState *State, ALfloat in, ALfloat *late)
{
ALfloat out, feed;
// Get the latest attenuated echo sample for output.
feed = AttenuatedDelayLineOut(&State->Echo.Delay,
State->Offset - State->Echo.Offset,
State->Echo.Coeff);
// Mix the output into the late reverb channels.
out = State->Echo.MixCoeff[0] * feed;
late[0] = (State->Echo.MixCoeff[1] * late[0]) + out;
late[1] = (State->Echo.MixCoeff[1] * late[1]) + out;
late[2] = (State->Echo.MixCoeff[1] * late[2]) + out;
late[3] = (State->Echo.MixCoeff[1] * late[3]) + out;
// Mix the energy-attenuated input with the output and pass it through
// the echo low-pass filter.
feed += State->Echo.DensityGain * in;
feed = lerp(feed, State->Echo.LpSample, State->Echo.LpCoeff);
State->Echo.LpSample = feed;
// Then the echo all-pass filter.
feed = AllpassInOut(&State->Echo.ApDelay,
State->Offset - State->Echo.ApOffset,
State->Offset, feed, State->Echo.ApFeedCoeff,
State->Echo.ApCoeff);
// Feed the delay with the mixed and filtered sample.
DelayLineIn(&State->Echo.Delay, State->Offset, feed);
}
static float LateAllPassInOut(IDirectSoundBufferImpl* dsb, unsigned int index, float in)
{
return AllpassInOut(&dsb->eax.Late.ApDelay[index],
dsb->eax.Offset - dsb->eax.Late.ApOffset[index],
dsb->eax.Offset, in, dsb->eax.Late.ApFeedCoeff,
dsb->eax.Late.ApCoeff[index]);
}
// All-pass input/output routine for late reverb.
static __inline ALfloat LateAllPassInOut(ALverbState *State, ALuint index, ALfloat in)
{
return AllpassInOut(&State->Late.ApDelay[index],
State->Offset - State->Late.ApOffset[index],
State->Offset, in, State->Late.ApFeedCoeff,
State->Late.ApCoeff[index]);
}
