debugger: implement scrolling in the hex view

debugger/hexview.go

@@ -56,6 +56,17 @@ func (m *HexView) moveSelection(delta int) bool {
 	newAddr := m.selectedAddr + delta
 	if newAddr >= 0 && newAddr < m.mem.Len() {
 		m.selectedAddr = newAddr
+		start, end := m.VisibleBytes()
+		newFirstLine := newAddr / 16
+		if newAddr < start {
+			newFirstLine = newFirstLine - (m.height * 4 / 5)
+			newFirstLine = max(newFirstLine, 0)
+			m.firstAddr = newFirstLine * 16
+		} else if newAddr >= end {
+			newFirstLine = newFirstLine - (m.height * 1 / 5)
+			newFirstLine = min(newFirstLine, (m.mem.Len()/16)-m.height)
+			m.firstAddr = newFirstLine * 16
+		}
 		return true
 	}
 	return false

debugger/main.go

@@ -14,7 +14,7 @@ func main() {
 	}
 	defer dbg.Close()
 
-	mem := memory.New(dbg, 768)
+	mem := memory.New(dbg, 4*1024)
 
 	if err := UI(mem); err != nil {
 		log.Fatal(err)