1 files changed, 39 insertions, 0 deletions
diff --git a/vm/memory.go b/vm/memory.go
new file mode 100644
index 0000000..0a9dd2c
--- /dev/null
+++ b/vm/memory.go
@@ -0,0 +1,39 @@
+package main
+
+import (
+	"github.com/holiman/uint256"
+	"log"
+)
+
+type Memory []byte
+
+// store 256b word at offset in memory
+func (m *Memory) sw(ost uint64, val *uint256.Int) {
+	if ost + 32 > uint64(len(*m)) {
+		*m = append(*m, make([]byte, ost + 32 - uint64(len(*m)))...)
+	}
+
+	bytes := val.Bytes32()
+	copy((*m)[ost:], bytes[:])
+}
+
+// store byte at offset in memory
+func (m *Memory) sb(ost uint64, val byte) {
+	if ost + 1 > uint64(len(*m)) {
+		*m = append(*m, make([]byte, ost + 1 - uint64(len(*m)))...)
+	}
+	
+	(*m)[ost] = val
+}
+
+// loads 256b word fron offset in memory
+func (m *Memory) ld(ost uint64) []byte {
+	if ost + 32 > uint64(len(*m)) {
+		log.Fatal("trying to load out of memory")
+	}
+
+	r := make([]byte, 32)
+	copy(r, (*m)[ost:ost+32])
+	return r
+}
+