diff options
Diffstat (limited to 'compression')
| -rw-r--r-- | compression/rle/read_write.go | 84 | ||||
| -rw-r--r-- | compression/rle/read_write_test.go | 118 |
2 files changed, 202 insertions, 0 deletions
diff --git a/compression/rle/read_write.go b/compression/rle/read_write.go new file mode 100644 index 000000000..dde0e41ab --- /dev/null +++ b/compression/rle/read_write.go @@ -0,0 +1,84 @@ +package rle + +import ( + "bytes" + "errors" + + "github.com/ethereum/go-ethereum/crypto" +) + +const ( + token byte = 0xfe + emptyShaToken = 0xfd + emptyListShaToken = 0xfe + tokenToken = 0xff +) + +var empty = crypto.Sha3([]byte("")) +var emptyList = crypto.Sha3([]byte{0x80}) + +func Decompress(dat []byte) ([]byte, error) { + buf := new(bytes.Buffer) + + for i := 0; i < len(dat); i++ { + if dat[i] == token { + if i+1 < len(dat) { + switch dat[i+1] { + case emptyShaToken: + buf.Write(empty) + case emptyListShaToken: + buf.Write(emptyList) + case tokenToken: + buf.WriteByte(token) + default: + buf.Write(make([]byte, int(dat[i+1]-2))) + } + i++ + } else { + return nil, errors.New("error reading bytes. token encountered without proceeding bytes") + } + } else { + buf.WriteByte(dat[i]) + } + } + + return buf.Bytes(), nil +} + +func compressChunk(dat []byte) (ret []byte, n int) { + switch { + case dat[0] == token: + return []byte{token, tokenToken}, 1 + case len(dat) > 1 && dat[0] == 0x0 && dat[1] == 0x0: + j := 0 + for j <= 254 && j < len(dat) { + if dat[j] != 0 { + break + } + j++ + } + return []byte{token, byte(j + 2)}, j + case len(dat) >= 32: + if dat[0] == empty[0] && bytes.Compare(dat[:32], empty) == 0 { + return []byte{token, emptyShaToken}, 32 + } else if dat[0] == emptyList[0] && bytes.Compare(dat[:32], emptyList) == 0 { + return []byte{token, emptyListShaToken}, 32 + } + fallthrough + default: + return dat[:1], 1 + } +} + +func Compress(dat []byte) []byte { + buf := new(bytes.Buffer) + + i := 0 + for i < len(dat) { + b, n := compressChunk(dat[i:]) + buf.Write(b) + i += n + } + + return buf.Bytes() +} diff --git a/compression/rle/read_write_test.go b/compression/rle/read_write_test.go new file mode 100644 index 000000000..e6aac9093 --- /dev/null +++ b/compression/rle/read_write_test.go @@ -0,0 +1,118 @@ +package rle + +import ( + "testing" + + checker "gopkg.in/check.v1" +) + +func Test(t *testing.T) { checker.TestingT(t) } + +type CompressionRleSuite struct{} + +var _ = checker.Suite(&CompressionRleSuite{}) + +func (s *CompressionRleSuite) TestDecompressSimple(c *checker.C) { + exp := []byte{0xc5, 0xd2, 0x46, 0x1, 0x86, 0xf7, 0x23, 0x3c, 0x92, 0x7e, 0x7d, 0xb2, 0xdc, 0xc7, 0x3, 0xc0, 0xe5, 0x0, 0xb6, 0x53, 0xca, 0x82, 0x27, 0x3b, 0x7b, 0xfa, 0xd8, 0x4, 0x5d, 0x85, 0xa4, 0x70} + res, err := Decompress([]byte{token, 0xfd}) + c.Assert(err, checker.IsNil) + c.Assert(res, checker.DeepEquals, exp) + // if bytes.Compare(res, exp) != 0 { + // t.Error("empty sha3", res) + // } + + exp = []byte{0x56, 0xe8, 0x1f, 0x17, 0x1b, 0xcc, 0x55, 0xa6, 0xff, 0x83, 0x45, 0xe6, 0x92, 0xc0, 0xf8, 0x6e, 0x5b, 0x48, 0xe0, 0x1b, 0x99, 0x6c, 0xad, 0xc0, 0x1, 0x62, 0x2f, 0xb5, 0xe3, 0x63, 0xb4, 0x21} + res, err = Decompress([]byte{token, 0xfe}) + c.Assert(err, checker.IsNil) + c.Assert(res, checker.DeepEquals, exp) + // if bytes.Compare(res, exp) != 0 { + // t.Error("0x80 sha3", res) + // } + + res, err = Decompress([]byte{token, 0xff}) + c.Assert(err, checker.IsNil) + c.Assert(res, checker.DeepEquals, []byte{token}) + // if bytes.Compare(res, []byte{token}) != 0 { + // t.Error("token", res) + // } + + res, err = Decompress([]byte{token, 12}) + c.Assert(err, checker.IsNil) + c.Assert(res, checker.DeepEquals, make([]byte, 10)) + // if bytes.Compare(res, make([]byte, 10)) != 0 { + // t.Error("10 * zero", res) + // } +} + +// func TestDecompressMulti(t *testing.T) { +// res, err := Decompress([]byte{token, 0xfd, token, 0xfe, token, 12}) +// if err != nil { +// t.Error(err) +// } + +// var exp []byte +// exp = append(exp, crypto.Sha3([]byte(""))...) +// exp = append(exp, crypto.Sha3([]byte{0x80})...) +// exp = append(exp, make([]byte, 10)...) + +// if bytes.Compare(res, res) != 0 { +// t.Error("Expected", exp, "result", res) +// } +// } + +// func TestCompressSimple(t *testing.T) { +// res := Compress([]byte{0, 0, 0, 0, 0}) +// if bytes.Compare(res, []byte{token, 7}) != 0 { +// t.Error("5 * zero", res) +// } + +// res = Compress(crypto.Sha3([]byte(""))) +// if bytes.Compare(res, []byte{token, emptyShaToken}) != 0 { +// t.Error("empty sha", res) +// } + +// res = Compress(crypto.Sha3([]byte{0x80})) +// if bytes.Compare(res, []byte{token, emptyListShaToken}) != 0 { +// t.Error("empty list sha", res) +// } + +// res = Compress([]byte{token}) +// if bytes.Compare(res, []byte{token, tokenToken}) != 0 { +// t.Error("token", res) +// } +// } + +// func TestCompressMulti(t *testing.T) { +// in := []byte{0, 0, 0, 0, 0} +// in = append(in, crypto.Sha3([]byte(""))...) +// in = append(in, crypto.Sha3([]byte{0x80})...) +// in = append(in, token) +// res := Compress(in) + +// exp := []byte{token, 7, token, emptyShaToken, token, emptyListShaToken, token, tokenToken} +// if bytes.Compare(res, exp) != 0 { +// t.Error("expected", exp, "got", res) +// } +// } + +// func TestCompressDecompress(t *testing.T) { +// var in []byte + +// for i := 0; i < 20; i++ { +// in = append(in, []byte{0, 0, 0, 0, 0}...) +// in = append(in, crypto.Sha3([]byte(""))...) +// in = append(in, crypto.Sha3([]byte{0x80})...) +// in = append(in, []byte{123, 2, 19, 89, 245, 254, 255, token, 98, 233}...) +// in = append(in, token) +// } + +// c := Compress(in) +// d, err := Decompress(c) +// if err != nil { +// t.Error(err) +// } + +// if bytes.Compare(d, in) != 0 { +// t.Error("multi failed\n", d, "\n", in) +// } +// } |