feat(gen&zecall): add function support

internal/zecall/generic.go

@@ -0,0 +1,38 @@
+package zecall
+
+import (
+	"errors"
+	"math"
+	"reflect"
+)
+
+type ReturnTypes interface {
+	~int | ~int8 | ~int16 | ~int32 | ~int64 | ~uint | ~uint8 |
+		~uint16 | ~uint32 | ~uint64 | ~uintptr | ~float32 | ~float64
+}
+
+// Call invokes a registered proc by name. For generated call only.
+// The go:uintptrescapes directive tells the compiler that args may contain
+// pointers converted to uintptr, so the GC will keep them alive during the call.
+//
+//go:uintptrescapes
+func Call[T ReturnTypes](name string, args ...uintptr) (r T, err error) {
+	r1, r2, err := Syscall(name, args...)
+	if err != nil {
+		return
+	}
+	k := reflect.TypeOf(r).Kind()
+	switch k {
+	case reflect.Int, reflect.Int8, reflect.Int16,
+		reflect.Int32, reflect.Int64, reflect.Uint, reflect.Uint8,
+		reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr:
+		r = (T)(r1)
+	case reflect.Float32:
+		r = (T)(math.Float32frombits(uint32(r2)))
+	case reflect.Float64:
+		r = (T)(math.Float64frombits(uint64(r2)))
+	default:
+		err = errors.New("zecall unsupported kind " + k.String())
+	}
+	return
+}