133 lines
3.6 KiB
Go
133 lines
3.6 KiB
Go
package encoding
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import (
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"errors"
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)
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// SizeOfNVarInt32 return the buffer size after encoding value as NVarInt32
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func SizeOfNVarInt32(value int32) int {
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return sizeOfNVarInt(int64(value), 32)
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}
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// EncodeNVarInt32 encode value as NVarInt32 to buffer
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func (codec *VarCodec) EncodeNVarInt32(buffer []byte, value int32) error {
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return codec.encodeNVarInt(buffer, int64(value))
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}
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// DecodeNVarInt32 decode to value as NVarInt32 from buffer
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func (codec *VarCodec) DecodeNVarInt32(buffer []byte, value *int32) error {
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var val = int64(*value)
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var err = codec.decodeNVarInt(buffer, &val)
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*value = int32(val)
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return err
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}
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// SizeOfNVarUInt32 return the buffer size after encoding value as NVarUInt32
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func SizeOfNVarUInt32(value uint32) int {
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return sizeOfNVarInt(int64(int32(value)), 32)
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}
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// EncodeNVarUInt32 encode value as NVarUInt32 to buffer
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func (codec *VarCodec) EncodeNVarUInt32(buffer []byte, value uint32) error {
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return codec.encodeNVarInt(buffer, int64(int32(value)))
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}
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// DecodeNVarUInt32 decode to value as NVarUInt32 from buffer
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func (codec *VarCodec) DecodeNVarUInt32(buffer []byte, value *uint32) error {
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var val = int64(int32(*value))
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var err = codec.decodeNVarInt(buffer, &val)
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*value = uint32(val)
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return err
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}
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// SizeOfNVarInt64 return the buffer size after encoding value as NVarInt64
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func SizeOfNVarInt64(value int64) int {
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return sizeOfNVarInt(value, 64)
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}
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// EncodeNVarInt64 encode value as NVarInt64 to buffer
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func (codec *VarCodec) EncodeNVarInt64(buffer []byte, value int64) error {
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return codec.encodeNVarInt(buffer, value)
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}
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// DecodeNVarInt64 decode to value as NVarInt64 from buffer
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func (codec *VarCodec) DecodeNVarInt64(buffer []byte, value *int64) error {
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return codec.decodeNVarInt(buffer, value)
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}
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// SizeOfNVarUInt64 return the buffer size after encoding value as NVarUInt64
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func SizeOfNVarUInt64(value uint64) int {
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return sizeOfNVarInt(int64(value), 64)
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}
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// EncodeNVarUInt64 encode value as NVarUInt64 to buffer
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func (codec *VarCodec) EncodeNVarUInt64(buffer []byte, value uint64) error {
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return codec.encodeNVarInt(buffer, int64(value))
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}
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// DecodeNVarUInt64 decode to value as NVarUInt64 from buffer
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func (codec *VarCodec) DecodeNVarUInt64(buffer []byte, value *uint64) error {
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var val = int64(*value)
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var err = codec.decodeNVarInt(buffer, &val)
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*value = uint64(val)
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return err
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}
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// SizeOfNVarInt return the buffer size after encoding value as NVarInt
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func sizeOfNVarInt(value int64, width int) int {
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const unit = 8 // bit width of encoding unit
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var lead = value >> (width - 1)
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for size := width / unit - 1; size > 0; size-- {
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var lookAhead = value >> (size*unit - 1)
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if lookAhead != lead {
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return size + 1
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}
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}
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return 1
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}
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func (codec *VarCodec) encodeNVarInt(buffer []byte, value int64) error {
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if codec == nil || codec.Size == 0 {
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return errors.New("nothing to encode")
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}
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const unit = 8 // bit width of encoding unit
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for codec.Size > 0 {
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if codec.Ptr >= len(buffer) {
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return ErrBufferInsufficient
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}
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codec.Size--
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buffer[codec.Ptr] = byte(value >> (codec.Size * unit))
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codec.Ptr++
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}
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return nil
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}
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func (codec *VarCodec) decodeNVarInt(buffer []byte, value *int64) error {
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if codec == nil || codec.Size == 0 {
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return errors.New("nothing to decode")
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}
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const unit = 8 // bit width of encoding unit
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if codec.Size > 0 { // initialize sign bit
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if codec.Ptr >= len(buffer) {
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return ErrBufferInsufficient
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}
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*value = int64(int8(buffer[codec.Ptr]) >> (unit - 1))
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codec.Size = -codec.Size
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}
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for codec.Size < 0 {
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if codec.Ptr >= len(buffer) {
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return ErrBufferInsufficient
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}
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codec.Size++
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*value = (*value << unit) | int64(buffer[codec.Ptr])
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codec.Ptr++
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}
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return nil
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}
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