Skip to content

Write VarInt as fast as possible by unrolling the loop #363

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Open
wants to merge 1 commit into
base: master
Choose a base branch
from
Open

Write VarInt as fast as possible by unrolling the loop #363

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
175 changes: 163 additions & 12 deletions minecraft/nbt/encoding.go
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -57,35 +57,186 @@ type networkLittleEndian struct{ littleEndian }

// WriteInt32 ...
func (networkLittleEndian) WriteInt32(w *offsetWriter, x int32) error {
ux := uint32(x) << 1
u := uint32(x) << 1
if x < 0 {
ux = ^ux
u = ^u
}
for ux >= 0x80 {
if err := w.WriteByte(byte(ux) | 0x80); err != nil {

if u < 1<<7 {
if err := w.WriteByte(byte(u)); err != nil {
return FailedWriteError{Op: "WriteInt32", Off: w.off}
}
ux >>= 7
return nil
}
if err := w.WriteByte(byte(ux)); err != nil {
if u < 1<<14 {
// Two WriteByte() calls on bytes.Buffer is faster than a single Write() with []byte.
if err := w.WriteByte(byte(u) | 0x80); err != nil {
return FailedWriteError{Op: "WriteInt32", Off: w.off}
}
if err := w.WriteByte(byte(u >> 7)); err != nil {
return FailedWriteError{Op: "WriteInt32", Off: w.off}
}
return nil
}
if u < 1<<21 {
if _, err := w.Write([]byte{
byte(u) | 0x80,
byte(u>>7) | 0x80,
byte(u >> 14),
}); err != nil {
return FailedWriteError{Op: "WriteInt32", Off: w.off}
}
return nil
}
if u < 1<<28 {
if _, err := w.Write([]byte{
byte(u) | 0x80,
byte(u>>7) | 0x80,
byte(u>>14) | 0x80,
byte(u >> 21),
}); err != nil {
return FailedWriteError{Op: "WriteInt32", Off: w.off}
}
return nil
}
if _, err := w.Write([]byte{
byte(u) | 0x80,
byte(u>>7) | 0x80,
byte(u>>14) | 0x80,
byte(u>>21) | 0x80,
byte(u >> 28),
}); err != nil {
return FailedWriteError{Op: "WriteInt32", Off: w.off}
}
return nil
}

// WriteInt64 ...
func (networkLittleEndian) WriteInt64(w *offsetWriter, x int64) error {
ux := uint64(x) << 1
u := uint64(x) << 1
if x < 0 {
ux = ^ux
u = ^u
}
for ux >= 0x80 {
if err := w.WriteByte(byte(ux) | 0x80); err != nil {

if u < 1<<7 {
if err := w.WriteByte(byte(u)); err != nil {
return FailedWriteError{Op: "WriteInt64", Off: w.off}
}
ux >>= 7
return nil
}
if err := w.WriteByte(byte(ux)); err != nil {
if u < 1<<14 {
// Two WriteByte() calls on bytes.Buffer is faster than a single Write() with []byte.
if err := w.WriteByte(byte(u) | 0x80); err != nil {
return FailedWriteError{Op: "WriteInt64", Off: w.off}
}
if err := w.WriteByte(byte(u >> 7)); err != nil {
return FailedWriteError{Op: "WriteInt64", Off: w.off}
}
return nil
}
if u < 1<<21 {
if _, err := w.Write([]byte{
byte(u) | 0x80,
byte(u>>7) | 0x80,
byte(u >> 14),
}); err != nil {
return FailedWriteError{Op: "WriteInt64", Off: w.off}
}
return nil
}
if u < 1<<28 {
if _, err := w.Write([]byte{
byte(u) | 0x80,
byte(u>>7) | 0x80,
byte(u>>14) | 0x80,
byte(u >> 21),
}); err != nil {
return FailedWriteError{Op: "WriteInt64", Off: w.off}
}
return nil
}
if u < 1<<35 {
if _, err := w.Write([]byte{
byte(u) | 0x80,
byte(u>>7) | 0x80,
byte(u>>14) | 0x80,
byte(u>>21) | 0x80,
byte(u >> 28),
}); err != nil {
return FailedWriteError{Op: "WriteInt64", Off: w.off}
}
return nil
}
if u < 1<<42 {
if _, err := w.Write([]byte{
byte(u) | 0x80,
byte(u>>7) | 0x80,
byte(u>>14) | 0x80,
byte(u>>21) | 0x80,
byte(u>>28) | 0x80,
byte(u >> 35),
}); err != nil {
return FailedWriteError{Op: "WriteInt64", Off: w.off}
}
return nil
}
if u < 1<<49 {
if _, err := w.Write([]byte{
byte(u) | 0x80,
byte(u>>7) | 0x80,
byte(u>>14) | 0x80,
byte(u>>21) | 0x80,
byte(u>>28) | 0x80,
byte(u>>35) | 0x80,
byte(u >> 42),
}); err != nil {
return FailedWriteError{Op: "WriteInt64", Off: w.off}
}
return nil
}
if u < 1<<56 {
if _, err := w.Write([]byte{
byte(u) | 0x80,
byte(u>>7) | 0x80,
byte(u>>14) | 0x80,
byte(u>>21) | 0x80,
byte(u>>28) | 0x80,
byte(u>>35) | 0x80,
byte(u>>42) | 0x80,
byte(u >> 49),
}); err != nil {
return FailedWriteError{Op: "WriteInt64", Off: w.off}
}
return nil
}
if u < 1<<63 {
if _, err := w.Write([]byte{
byte(u) | 0x80,
byte(u>>7) | 0x80,
byte(u>>14) | 0x80,
byte(u>>21) | 0x80,
byte(u>>28) | 0x80,
byte(u>>35) | 0x80,
byte(u>>42) | 0x80,
byte(u>>49) | 0x80,
byte(u >> 56),
}); err != nil {
return FailedWriteError{Op: "WriteInt64", Off: w.off}
}
return nil
}
if _, err := w.Write([]byte{
byte(u) | 0x80,
byte(u>>7) | 0x80,
byte(u>>14) | 0x80,
byte(u>>21) | 0x80,
byte(u>>28) | 0x80,
byte(u>>35) | 0x80,
byte(u>>42) | 0x80,
byte(u>>49) | 0x80,
byte(u>>56) | 0x80,
byte(u >> 63),
}); err != nil {
return FailedWriteError{Op: "WriteInt64", Off: w.off}
}
return nil
Expand Down
Loading