4.0初步改造

util/bits/pio/vec.go

@@ -0,0 +1,68 @@
+package pio
+
+func VecLen(vec [][]byte) (n int) {
+	for _, b := range vec {
+		n += len(b)
+	}
+	return
+}
+
+func VecSliceTo(in [][]byte, out [][]byte, s int, e int) (n int) {
+	if s < 0 {
+		s = 0
+	}
+
+	if e >= 0 && e < s {
+		panic("pio: VecSlice start > end")
+	}
+
+	i := 0
+	off := 0
+	for s > 0 && i < len(in) {
+		left := len(in[i])
+		read := s
+		if left < read {
+			read = left
+		}
+		left -= read
+		off += read
+		s -= read
+		e -= read
+		if left == 0 {
+			i++
+			off = 0
+		}
+	}
+	if s > 0 {
+		panic("pio: VecSlice start out of range")
+	}
+
+	for e != 0 && i < len(in) {
+		left := len(in[i]) - off
+		read := left
+		if e > 0 && e < read {
+			read = e
+		}
+		out[n] = in[i][off : off+read]
+		n++
+		left -= read
+		e -= read
+		off += read
+		if left == 0 {
+			i++
+			off = 0
+		}
+	}
+	if e > 0 {
+		panic("pio: VecSlice end out of range")
+	}
+
+	return
+}
+
+func VecSlice(in [][]byte, s int, e int) (out [][]byte) {
+	out = make([][]byte, len(in))
+	n := VecSliceTo(in, out, s, e)
+	out = out[:n]
+	return
+}