first commit

av/pktque/timeline.go

@@ -0,0 +1,61 @@
+package pktque
+
+import (
+	"time"
+)
+
+/*
+pop                                   push
+
+     seg                 seg        seg
+  |--------|         |---------|   |---|
+     20ms                40ms       5ms
+----------------- time -------------------->
+headtm                               tailtm
+*/
+
+type tlSeg struct {
+	tm, dur time.Duration
+}
+
+type Timeline struct {
+	segs []tlSeg
+	headtm time.Duration
+}
+
+func (self *Timeline) Push(tm time.Duration, dur time.Duration) {
+	if len(self.segs) > 0 {
+		tail := self.segs[len(self.segs)-1]
+		diff := tm-(tail.tm+tail.dur)
+		if diff < 0 {
+			tm -= diff
+		}
+	}
+	self.segs = append(self.segs, tlSeg{tm, dur})
+}
+
+func (self *Timeline) Pop(dur time.Duration) (tm time.Duration) {
+	if len(self.segs) == 0 {
+		return self.headtm
+	}
+
+	tm = self.segs[0].tm
+	for dur > 0 && len(self.segs) > 0 {
+		seg := &self.segs[0]
+		sub := dur
+		if seg.dur < sub {
+			sub = seg.dur
+		}
+		seg.dur -= sub
+		dur -= sub
+		seg.tm += sub
+		self.headtm += sub
+		if seg.dur == 0 {
+			copy(self.segs[0:], self.segs[1:])
+			self.segs = self.segs[:len(self.segs)-1]
+		}
+	}
+
+	return
+}
+