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authorDeterminant <[email protected]>2020-06-28 14:47:41 -0400
committerDeterminant <[email protected]>2020-06-28 14:47:41 -0400
commitd235e2c6a5788ec4a6cff15a16f56b38a3876a0d (patch)
tree5f2727f7a50ee5840f889c82776d3a30a88dd59b /core/vm/memory.go
parent13ebd8bd9468e9d769d598b0ca2afb72ba78cb97 (diff)
...
Diffstat (limited to 'core/vm/memory.go')
-rw-r--r--core/vm/memory.go124
1 files changed, 124 insertions, 0 deletions
diff --git a/core/vm/memory.go b/core/vm/memory.go
new file mode 100644
index 0000000..5408707
--- /dev/null
+++ b/core/vm/memory.go
@@ -0,0 +1,124 @@
+// Copyright 2015 The go-ethereum Authors
+// This file is part of the go-ethereum library.
+//
+// The go-ethereum library is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Lesser General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// The go-ethereum library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public License
+// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
+
+package vm
+
+import (
+ "fmt"
+ "math/big"
+
+ "github.com/ava-labs/go-ethereum/common/math"
+)
+
+// Memory implements a simple memory model for the ethereum virtual machine.
+type Memory struct {
+ store []byte
+ lastGasCost uint64
+}
+
+// NewMemory returns a new memory model.
+func NewMemory() *Memory {
+ return &Memory{}
+}
+
+// Set sets offset + size to value
+func (m *Memory) Set(offset, size uint64, value []byte) {
+ // It's possible the offset is greater than 0 and size equals 0. This is because
+ // the calcMemSize (common.go) could potentially return 0 when size is zero (NO-OP)
+ if size > 0 {
+ // length of store may never be less than offset + size.
+ // The store should be resized PRIOR to setting the memory
+ if offset+size > uint64(len(m.store)) {
+ panic("invalid memory: store empty")
+ }
+ copy(m.store[offset:offset+size], value)
+ }
+}
+
+// Set32 sets the 32 bytes starting at offset to the value of val, left-padded with zeroes to
+// 32 bytes.
+func (m *Memory) Set32(offset uint64, val *big.Int) {
+ // length of store may never be less than offset + size.
+ // The store should be resized PRIOR to setting the memory
+ if offset+32 > uint64(len(m.store)) {
+ panic("invalid memory: store empty")
+ }
+ // Zero the memory area
+ copy(m.store[offset:offset+32], []byte{0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0})
+ // Fill in relevant bits
+ math.ReadBits(val, m.store[offset:offset+32])
+}
+
+// Resize resizes the memory to size
+func (m *Memory) Resize(size uint64) {
+ if uint64(m.Len()) < size {
+ m.store = append(m.store, make([]byte, size-uint64(m.Len()))...)
+ }
+}
+
+// Get returns offset + size as a new slice
+func (m *Memory) Get(offset, size int64) (cpy []byte) {
+ if size == 0 {
+ return nil
+ }
+
+ if len(m.store) > int(offset) {
+ cpy = make([]byte, size)
+ copy(cpy, m.store[offset:offset+size])
+
+ return
+ }
+
+ return
+}
+
+// GetPtr returns the offset + size
+func (m *Memory) GetPtr(offset, size int64) []byte {
+ if size == 0 {
+ return nil
+ }
+
+ if len(m.store) > int(offset) {
+ return m.store[offset : offset+size]
+ }
+
+ return nil
+}
+
+// Len returns the length of the backing slice
+func (m *Memory) Len() int {
+ return len(m.store)
+}
+
+// Data returns the backing slice
+func (m *Memory) Data() []byte {
+ return m.store
+}
+
+// Print dumps the content of the memory.
+func (m *Memory) Print() {
+ fmt.Printf("### mem %d bytes ###\n", len(m.store))
+ if len(m.store) > 0 {
+ addr := 0
+ for i := 0; i+32 <= len(m.store); i += 32 {
+ fmt.Printf("%03d: % x\n", addr, m.store[i:i+32])
+ addr++
+ }
+ } else {
+ fmt.Println("-- empty --")
+ }
+ fmt.Println("####################")
+}