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memory.go
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memory.go
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// 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 evm
import "github.com/holiman/uint256"
// evm的简单内存模型
type Memory struct {
store []byte
lastGasCost uint64
}
func NewMemory() *Memory {
return &Memory{}
}
func (m *Memory) Set(offset, size uint64, val []byte) {
if size > 0 {
if offset+size > uint64(m.Len()) {
panic("invalid memory: store empty")
}
copy(m.store[offset:offset+size], val)
}
}
// solidity的int/int256/uint/uint256数值类型
func (m *Memory) Set32(offset uint64, val *uint256.Int) {
if offset+32 > uint64(m.Len()) {
panic("invalid memory: store empty")
}
b32 := val.Bytes32()
copy(m.store[offset:], b32[:])
}
func (m *Memory) Resize(size uint64) {
if uint64(m.Len()) < size {
m.store = append(m.store, make([]byte, size-uint64(m.Len()))...)
}
}
func (m *Memory) Len() int {
return len(m.store)
}
func (m *Memory) Data() []byte {
return m.store
}
// 复制src位置的数据到dst位置,数据可能会覆盖
// 默认slice容量足够大, 否则会panic
func (m *Memory) Copy(dst, src, len uint64) {
if len == 0 {
return
}
copy(m.store[dst:], m.store[src:src+len])
}
// 复制Memory中指定位置的数据到新的Slice中,并返回
func (m *Memory) GetCopy(offset, size int64) (cpy []byte) {
if size == 0 {
return nil
}
if m.Len() > int(offset) {
cpy = make([]byte, size)
copy(cpy, m.store[offset:offset+size])
}
return
}
// 返回Memory指定位置数据的指针
func (m *Memory) GetPtr(offset, size int64) []byte {
if size == 0 {
return nil
}
if m.Len() > int(offset) {
return m.store[offset : offset+size]
}
return nil
}