start to implement operand types and checks

operand/types.go

@@ -0,0 +1,34 @@
+package operand
+
+import (
+	"fmt"
+
+	"github.com/mmcloughlin/avo/reg"
+)
+
+type Mem struct {
+	Disp  int
+	Base  reg.Register
+	Index reg.Register
+	Scale uint8
+}
+
+func (m Mem) Asm() string {
+	a := ""
+	if m.Disp != 0 {
+		a += fmt.Sprintf("%d", m.Disp)
+	}
+	if m.Base != nil {
+		a += fmt.Sprintf("(%s)", m.Base.Asm())
+	}
+	if m.Index != nil && m.Scale != 0 {
+		a += fmt.Sprintf("(%s*%d)", m.Index.Asm(), m.Scale)
+	}
+	return a
+}
+
+type Imm uint64
+
+func (i Imm) Asm() string {
+	return fmt.Sprintf("%#x", uint64(i))
+}