a7bb9496ae
Vanilla-faithful overworld generator (final_density + multi-noise biomes), full connection lifecycle (status/login/configuration/play), chunk streaming, creative block editing, and the protocol/nbt/registry infrastructure.
59 lines
1.6 KiB
Go
59 lines
1.6 KiB
Go
package nbt
|
|
|
|
import (
|
|
"errors"
|
|
"unicode/utf16"
|
|
)
|
|
|
|
// errBadMUTF8 is returned when a modified-UTF-8 byte sequence is malformed.
|
|
var errBadMUTF8 = errors.New("nbt: invalid modified UTF-8")
|
|
|
|
// encodeModifiedUTF8 encodes s as Java modified UTF-8: ASCII stays one byte,
|
|
// NUL and code points up to U+07FF take two bytes, U+0800..U+FFFF take three,
|
|
// and supplementary code points are split into a surrogate pair (six bytes).
|
|
func encodeModifiedUTF8(dst []byte, s string) []byte {
|
|
for _, u := range utf16.Encode([]rune(s)) {
|
|
switch {
|
|
case u >= 0x0001 && u <= 0x007F:
|
|
dst = append(dst, byte(u))
|
|
case u == 0 || u <= 0x07FF:
|
|
dst = append(dst,
|
|
0xC0|byte(u>>6),
|
|
0x80|byte(u&0x3F))
|
|
default:
|
|
dst = append(dst,
|
|
0xE0|byte(u>>12),
|
|
0x80|byte((u>>6)&0x3F),
|
|
0x80|byte(u&0x3F))
|
|
}
|
|
}
|
|
return dst
|
|
}
|
|
|
|
// decodeModifiedUTF8 decodes b (length-delimited modified UTF-8) into a string.
|
|
func decodeModifiedUTF8(b []byte) (string, error) {
|
|
units := make([]uint16, 0, len(b))
|
|
for i := 0; i < len(b); {
|
|
c := b[i]
|
|
switch {
|
|
case c&0x80 == 0: // 0xxxxxxx
|
|
units = append(units, uint16(c))
|
|
i++
|
|
case c&0xE0 == 0xC0: // 110xxxxx 10xxxxxx
|
|
if i+1 >= len(b) || b[i+1]&0xC0 != 0x80 {
|
|
return "", errBadMUTF8
|
|
}
|
|
units = append(units, uint16(c&0x1F)<<6|uint16(b[i+1]&0x3F))
|
|
i += 2
|
|
case c&0xF0 == 0xE0: // 1110xxxx 10xxxxxx 10xxxxxx
|
|
if i+2 >= len(b) || b[i+1]&0xC0 != 0x80 || b[i+2]&0xC0 != 0x80 {
|
|
return "", errBadMUTF8
|
|
}
|
|
units = append(units, uint16(c&0x0F)<<12|uint16(b[i+1]&0x3F)<<6|uint16(b[i+2]&0x3F))
|
|
i += 3
|
|
default:
|
|
return "", errBadMUTF8
|
|
}
|
|
}
|
|
return string(utf16.Decode(units)), nil
|
|
}
|