mirror of
https://github.com/superseriousbusiness/gotosocial.git
synced 2025-11-03 18:42:25 -06:00
82 lines
1.9 KiB
Go
82 lines
1.9 KiB
Go
// Copyright 2019+ Klaus Post. All rights reserved.
|
|
// License information can be found in the LICENSE file.
|
|
// Based on work by Yann Collet, released under BSD License.
|
|
|
|
package zstd
|
|
|
|
// byteReader provides a byte reader that reads
|
|
// little endian values from a byte stream.
|
|
// The input stream is manually advanced.
|
|
// The reader performs no bounds checks.
|
|
type byteReader struct {
|
|
b []byte
|
|
off int
|
|
}
|
|
|
|
// advance the stream b n bytes.
|
|
func (b *byteReader) advance(n uint) {
|
|
b.off += int(n)
|
|
}
|
|
|
|
// overread returns whether we have advanced too far.
|
|
func (b *byteReader) overread() bool {
|
|
return b.off > len(b.b)
|
|
}
|
|
|
|
// Int32 returns a little endian int32 starting at current offset.
|
|
func (b byteReader) Int32() int32 {
|
|
b2 := b.b[b.off:]
|
|
b2 = b2[:4]
|
|
v3 := int32(b2[3])
|
|
v2 := int32(b2[2])
|
|
v1 := int32(b2[1])
|
|
v0 := int32(b2[0])
|
|
return v0 | (v1 << 8) | (v2 << 16) | (v3 << 24)
|
|
}
|
|
|
|
// Uint8 returns the next byte
|
|
func (b *byteReader) Uint8() uint8 {
|
|
v := b.b[b.off]
|
|
return v
|
|
}
|
|
|
|
// Uint32 returns a little endian uint32 starting at current offset.
|
|
func (b byteReader) Uint32() uint32 {
|
|
if r := b.remain(); r < 4 {
|
|
// Very rare
|
|
v := uint32(0)
|
|
for i := 1; i <= r; i++ {
|
|
v = (v << 8) | uint32(b.b[len(b.b)-i])
|
|
}
|
|
return v
|
|
}
|
|
b2 := b.b[b.off:]
|
|
b2 = b2[:4]
|
|
v3 := uint32(b2[3])
|
|
v2 := uint32(b2[2])
|
|
v1 := uint32(b2[1])
|
|
v0 := uint32(b2[0])
|
|
return v0 | (v1 << 8) | (v2 << 16) | (v3 << 24)
|
|
}
|
|
|
|
// Uint32NC returns a little endian uint32 starting at current offset.
|
|
// The caller must be sure if there are at least 4 bytes left.
|
|
func (b byteReader) Uint32NC() uint32 {
|
|
b2 := b.b[b.off:]
|
|
b2 = b2[:4]
|
|
v3 := uint32(b2[3])
|
|
v2 := uint32(b2[2])
|
|
v1 := uint32(b2[1])
|
|
v0 := uint32(b2[0])
|
|
return v0 | (v1 << 8) | (v2 << 16) | (v3 << 24)
|
|
}
|
|
|
|
// unread returns the unread portion of the input.
|
|
func (b byteReader) unread() []byte {
|
|
return b.b[b.off:]
|
|
}
|
|
|
|
// remain will return the number of bytes remaining.
|
|
func (b byteReader) remain() int {
|
|
return len(b.b) - b.off
|
|
}
|