diff --git a/common/math/big.go b/common/math/big.go index fd0174b366..7872786503 100644 --- a/common/math/big.go +++ b/common/math/big.go @@ -130,6 +130,34 @@ func PaddedBigBytes(bigint *big.Int, n int) []byte { return ret } +// bigEndianByteAt returns the byte at position n, +// in Big-Endian encoding +// So n==0 returns the least significant byte +func bigEndianByteAt(bigint *big.Int, n int) byte { + words := bigint.Bits() + // Check word-bucket the byte will reside in + i := n / wordBytes + if i >= len(words) { + return byte(0) + } + word := words[i] + // Offset of the byte + shift := 8 * uint(n%wordBytes) + + return byte(word >> shift) +} + +// Byte returns the byte at position n, +// with the supplied padlength in Little-Endian encoding. +// n==0 returns the MSB +// Example: bigint '5', padlength 32, n=31 => 5 +func Byte(bigint *big.Int, padlength, n int) byte { + if n >= padlength { + return byte(0) + } + return bigEndianByteAt(bigint, padlength-1-n) +} + // ReadBits encodes the absolute value of bigint as big-endian bytes. Callers must ensure // that buf has enough space. If buf is too short the result will be incomplete. func ReadBits(bigint *big.Int, buf []byte) { diff --git a/common/math/big_test.go b/common/math/big_test.go index e789bd18e1..be9810dc8c 100644 --- a/common/math/big_test.go +++ b/common/math/big_test.go @@ -21,6 +21,8 @@ import ( "encoding/hex" "math/big" "testing" + + "github.com/ethereum/go-ethereum/common" ) func TestHexOrDecimal256(t *testing.T) { @@ -133,8 +135,44 @@ func TestPaddedBigBytes(t *testing.T) { } } -func BenchmarkPaddedBigBytes(b *testing.B) { +func BenchmarkPaddedBigBytesLargePadding(b *testing.B) { bigint := MustParseBig256("123456789123456789123456789123456789") + for i := 0; i < b.N; i++ { + PaddedBigBytes(bigint, 200) + } +} + +func BenchmarkPaddedBigBytesSmallPadding(b *testing.B) { + bigint := MustParseBig256("0x18F8F8F1000111000110011100222004330052300000000000000000FEFCF3CC") + for i := 0; i < b.N; i++ { + PaddedBigBytes(bigint, 5) + } +} + +func BenchmarkPaddedBigBytesSmallOnePadding(b *testing.B) { + bigint := MustParseBig256("0x18F8F8F1000111000110011100222004330052300000000000000000FEFCF3CC") + for i := 0; i < b.N; i++ { + PaddedBigBytes(bigint, 32) + } +} + +func BenchmarkByteAtBrandNew(b *testing.B) { + bigint := MustParseBig256("0x18F8F8F1000111000110011100222004330052300000000000000000FEFCF3CC") + for i := 0; i < b.N; i++ { + bigEndianByteAt(bigint, 15) + } +} + +func BenchmarkByteAt(b *testing.B) { + bigint := MustParseBig256("0x18F8F8F1000111000110011100222004330052300000000000000000FEFCF3CC") + for i := 0; i < b.N; i++ { + bigEndianByteAt(bigint, 15) + } +} + +func BenchmarkByteAtOld(b *testing.B) { + + bigint := MustParseBig256("0x18F8F8F1000111000110011100222004330052300000000000000000FEFCF3CC") for i := 0; i < b.N; i++ { PaddedBigBytes(bigint, 32) } @@ -174,6 +212,65 @@ func TestU256(t *testing.T) { } } +func TestBigEndianByteAt(t *testing.T) { + tests := []struct { + x string + y int + exp byte + }{ + {"00", 0, 0x00}, + {"01", 1, 0x00}, + {"00", 1, 0x00}, + {"01", 0, 0x01}, + {"0000000000000000000000000000000000000000000000000000000000102030", 0, 0x30}, + {"0000000000000000000000000000000000000000000000000000000000102030", 1, 0x20}, + {"ABCDEF0908070605040302010000000000000000000000000000000000000000", 31, 0xAB}, + {"ABCDEF0908070605040302010000000000000000000000000000000000000000", 32, 0x00}, + {"ABCDEF0908070605040302010000000000000000000000000000000000000000", 500, 0x00}, + } + for _, test := range tests { + v := new(big.Int).SetBytes(common.Hex2Bytes(test.x)) + actual := bigEndianByteAt(v, test.y) + if actual != test.exp { + t.Fatalf("Expected [%v] %v:th byte to be %v, was %v.", test.x, test.y, test.exp, actual) + } + + } +} +func TestLittleEndianByteAt(t *testing.T) { + tests := []struct { + x string + y int + exp byte + }{ + {"00", 0, 0x00}, + {"01", 1, 0x00}, + {"00", 1, 0x00}, + {"01", 0, 0x00}, + {"0000000000000000000000000000000000000000000000000000000000102030", 0, 0x00}, + {"0000000000000000000000000000000000000000000000000000000000102030", 1, 0x00}, + {"ABCDEF0908070605040302010000000000000000000000000000000000000000", 31, 0x00}, + {"ABCDEF0908070605040302010000000000000000000000000000000000000000", 32, 0x00}, + {"ABCDEF0908070605040302010000000000000000000000000000000000000000", 0, 0xAB}, + {"ABCDEF0908070605040302010000000000000000000000000000000000000000", 1, 0xCD}, + {"00CDEF090807060504030201ffffffffffffffffffffffffffffffffffffffff", 0, 0x00}, + {"00CDEF090807060504030201ffffffffffffffffffffffffffffffffffffffff", 1, 0xCD}, + {"0000000000000000000000000000000000000000000000000000000000102030", 31, 0x30}, + {"0000000000000000000000000000000000000000000000000000000000102030", 30, 0x20}, + {"ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff", 32, 0x0}, + {"ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff", 31, 0xFF}, + {"ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff", 0xFFFF, 0x0}, + } + for _, test := range tests { + v := new(big.Int).SetBytes(common.Hex2Bytes(test.x)) + actual := Byte(v, 32, test.y) + if actual != test.exp { + t.Fatalf("Expected [%v] %v:th byte to be %v, was %v.", test.x, test.y, test.exp, actual) + } + + } +} + func TestS256(t *testing.T) { tests := []struct{ x, y *big.Int }{ {x: big.NewInt(0), y: big.NewInt(0)}, diff --git a/core/vm/instructions.go b/core/vm/instructions.go index 42f1781d88..f5164fcdd4 100644 --- a/core/vm/instructions.go +++ b/core/vm/instructions.go @@ -256,15 +256,14 @@ func opXor(pc *uint64, evm *EVM, contract *Contract, memory *Memory, stack *Stac } func opByte(pc *uint64, evm *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) { - th, val := stack.pop(), stack.pop() - if th.Cmp(big.NewInt(32)) < 0 { - byte := evm.interpreter.intPool.get().SetInt64(int64(math.PaddedBigBytes(val, 32)[th.Int64()])) - stack.push(byte) + th, val := stack.pop(), stack.peek() + if th.Cmp(common.Big32) < 0 { + b := math.Byte(val, 32, int(th.Int64())) + val.SetUint64(uint64(b)) } else { - stack.push(new(big.Int)) + val.SetUint64(0) } - - evm.interpreter.intPool.put(th, val) + evm.interpreter.intPool.put(th) return nil, nil } func opAddmod(pc *uint64, evm *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) { diff --git a/core/vm/instructions_test.go b/core/vm/instructions_test.go new file mode 100644 index 0000000000..ae428aeaba --- /dev/null +++ b/core/vm/instructions_test.go @@ -0,0 +1,42 @@ +package vm + +import ( + "math/big" + "testing" + + "github.com/ethereum/go-ethereum/common" + "github.com/ethereum/go-ethereum/params" +) + +func TestByteOp(t *testing.T) { + var ( + env = NewEVM(Context{}, nil, params.TestChainConfig, Config{EnableJit: false, ForceJit: false}) + stack = newstack() + ) + tests := []struct { + v string + th uint64 + expected *big.Int + }{ + {"ABCDEF0908070605040302010000000000000000000000000000000000000000", 0, big.NewInt(0xAB)}, + {"ABCDEF0908070605040302010000000000000000000000000000000000000000", 1, big.NewInt(0xCD)}, + {"00CDEF090807060504030201ffffffffffffffffffffffffffffffffffffffff", 0, big.NewInt(0x00)}, + {"00CDEF090807060504030201ffffffffffffffffffffffffffffffffffffffff", 1, big.NewInt(0xCD)}, + {"0000000000000000000000000000000000000000000000000000000000102030", 31, big.NewInt(0x30)}, + {"0000000000000000000000000000000000000000000000000000000000102030", 30, big.NewInt(0x20)}, + {"ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff", 32, big.NewInt(0x0)}, + {"ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff", 0xFFFFFFFFFFFFFFFF, big.NewInt(0x0)}, + } + pc := uint64(0) + for _, test := range tests { + val := new(big.Int).SetBytes(common.Hex2Bytes(test.v)) + th := new(big.Int).SetUint64(test.th) + stack.push(val) + stack.push(th) + opByte(&pc, env, nil, nil, stack) + actual := stack.pop() + if actual.Cmp(test.expected) != 0 { + t.Fatalf("Expected [%v] %v:th byte to be %v, was %v.", test.v, test.th, test.expected, actual) + } + } +}