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path: root/ber/len.go
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package ber

import (
	"io"
)

func UnmarshalLen(r io.ByteReader) int {
	b, _ := r.ReadByte()
	if b&0x80 == 0 {
		return int(b)
	}
	n := int(b & 0x7f)
	var i int
	for k := 0; k <= n; k++ {
		b, _ := r.ReadByte()
		i |= int(b) << uint(k*8)
	}
	return i
}

func unmarshalLen(b []byte) (i, n int) {
	if b[0]&0x80 == 0 {
		return int(b[0]), 1
	}
	n = int(b[0] & 0x7f)
	for k := 0; k <= n; k++ {
		i |= int(b[k]) << uint((k-1)*8)
	}
	return i, n + 1
}

func lenLen(i int) (n int) {
	for ; i > 255; i >>= 8 {
		n++
	}
	return n + 1
}

func MarshalLen(i int) []byte {
	if i < 0x80 {
		return []byte{byte(i)}
	}
	n := lenLen(i)
	b := []byte{byte(n) | 0x80}
	for ; n > 0; n-- {
		b = append(b, byte(i>>uint((n-1)*8)))
	}
	return b
}