acpi: tag entities with the handle of the table that defines them

This allows us to implement the Unload opcode which given a handle,
removes all entities that are tagged by it.

src/gopheros/device/acpi/aml/parser_test.go

@@ -33,7 +33,7 @@ func TestParser(t *testing.T) {
 
 		for _, tableName := range spec {
 			tableName := strings.Replace(tableName, ".aml", "", -1)
-			if err := p.ParseAML(tableName, resolver.LookupTable(tableName)); err != nil {
+			if err := p.ParseAML(0, tableName, resolver.LookupTable(tableName)); err != nil {
 				t.Errorf("[spec %d] [%s]: %v", specIndex, tableName, err)
 				break
 			}
@@ -41,6 +41,56 @@ func TestParser(t *testing.T) {
 	}
 }
 
+func TestTableHandleAssignment(t *testing.T) {
+	var resolver = mockResolver{tableFiles: []string{"parser-testsuite-DSDT.aml"}}
+
+	// Create default scopes
+	rootNS := &scopeEntity{op: opScope, name: `\`}
+	rootNS.Append(&scopeEntity{op: opScope, name: `_GPE`}) // General events in GPE register block
+	rootNS.Append(&scopeEntity{op: opScope, name: `_PR_`}) // ACPI 1.0 processor namespace
+	rootNS.Append(&scopeEntity{op: opScope, name: `_SB_`}) // System bus with all device objects
+	rootNS.Append(&scopeEntity{op: opScope, name: `_SI_`}) // System indicators
+	rootNS.Append(&scopeEntity{op: opScope, name: `_TZ_`}) // ACPI 1.0 thermal zone namespace
+
+	p := NewParser(ioutil.Discard, rootNS)
+
+	expHandle := uint8(42)
+	tableName := "parser-testsuite-DSDT"
+	if err := p.ParseAML(expHandle, tableName, resolver.LookupTable(tableName)); err != nil {
+		t.Error(err)
+	}
+
+	// Drop all entities that were assigned the handle value
+	var unloadList []Entity
+	scopeVisit(0, p.root, EntityTypeAny, func(_ int, ent Entity) bool {
+		if ent.TableHandle() == expHandle {
+			unloadList = append(unloadList, ent)
+			return false
+		}
+		return true
+	})
+
+	for _, ent := range unloadList {
+		if p := ent.Parent(); p != nil {
+			p.removeChild(ent)
+		}
+	}
+
+	// We should end up with the original tree
+	var visitedNodes int
+	scopeVisit(0, p.root, EntityTypeAny, func(_ int, ent Entity) bool {
+		visitedNodes++
+		if ent.TableHandle() == expHandle {
+			t.Errorf("encounted entity that should have been pruned: %#+v", ent)
+		}
+		return true
+	})
+
+	if exp := len(rootNS.Children()) + 1; visitedNodes != exp {
+		t.Errorf("expected to visit %d nodes; visited %d", exp, visitedNodes)
+	}
+}
+
 func pkgDir() string {
 	_, f, _, _ := runtime.Caller(1)
 	return filepath.Dir(f)