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package kcp
const maxAutoTuneSamples = 258
// pulse represents a 0/1 signal with time sequence
type pulse struct {
bit bool // 0 or 1
seq uint32 // sequence of the signal
}
// autoTune object
type autoTune struct {
pulses [maxAutoTuneSamples]pulse
}
// Sample adds a signal sample to the pulse buffer
func (tune *autoTune) Sample(bit bool, seq uint32) {
tune.pulses[seq%maxAutoTuneSamples] = pulse{bit, seq}
}
// Find a period for a given signal
// returns -1 if not found
//
// --- ------
// | |
// |______________|
// Period
// Falling Edge Rising Edge
func (tune *autoTune) FindPeriod(bit bool) int {
// last pulse and initial index setup
lastPulse := tune.pulses[0]
idx := 1
// left edge
var leftEdge int
for ; idx < len(tune.pulses); idx++ {
if lastPulse.bit != bit && tune.pulses[idx].bit == bit { // edge found
if lastPulse.seq+1 == tune.pulses[idx].seq { // ensure edge continuity
leftEdge = idx
break
}
}
lastPulse = tune.pulses[idx]
}
// right edge
var rightEdge int
lastPulse = tune.pulses[leftEdge]
idx = leftEdge + 1
for ; idx < len(tune.pulses); idx++ {
if lastPulse.seq+1 == tune.pulses[idx].seq { // ensure pulses in this level monotonic
if lastPulse.bit == bit && tune.pulses[idx].bit != bit { // edge found
rightEdge = idx
break
}
} else {
return -1
}
lastPulse = tune.pulses[idx]
}
return rightEdge - leftEdge
}
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