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path: root/core/vm/memory.go
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package vm

import "fmt"

type Memory struct {
    store []byte
}

func NewMemory() *Memory {
    return &Memory{nil}
}

func (m *Memory) Set(offset, size uint64, value []byte) {
    // length of store may never be less than offset + size.
    // The store should be resized PRIOR to setting the memory
    if size > uint64(len(m.store)) {
        panic("INVALID memory: store empty")
    }

    // 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 {
        copy(m.store[offset:offset+size], value)
    }
}

func (m *Memory) Resize(size uint64) {
    if uint64(m.Len()) < size {
        m.store = append(m.store, make([]byte, size-uint64(m.Len()))...)
    }
}

func (self *Memory) Get(offset, size int64) (cpy []byte) {
    if size == 0 {
        return nil
    }

    if len(self.store) > int(offset) {
        cpy = make([]byte, size)
        copy(cpy, self.store[offset:offset+size])

        return
    }

    return
}

func (self *Memory) GetPtr(offset, size int64) []byte {
    if size == 0 {
        return nil
    }

    if len(self.store) > int(offset) {
        return self.store[offset : offset+size]
    }

    return nil
}

func (m *Memory) Len() int {
    return len(m.store)
}

func (m *Memory) Data() []byte {
    return m.store
}

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("####################")
}