Support negatives INT128

driver_test.go

@@ -480,6 +480,41 @@ func TestInt128(t *testing.T) {
 	conn.Close()
 }
 
+func TestNegativeInt128(t *testing.T) {
+	conn, err := sql.Open("firebirdsql_createdb", GetTestDSN("test_negative_int128_"))
+	if err != nil {
+		t.Fatalf("Error connecting: %v", err)
+	}
+
+	firebird_major_version := get_firebird_major_version(conn)
+	if firebird_major_version < 4 {
+		return
+	}
+
+	sql := `
+        CREATE TABLE test_negative_int128 (
+            i int128
+        )
+    `
+	conn.Exec(sql)
+	conn.Exec("insert into test_negative_int128(i) values (-170141183460469231731687303715884105727)")
+
+	var i128 *big.Int
+	err = conn.QueryRow("SELECT i FROM test_negative_int128").Scan(&i128)
+	if err != nil {
+		t.Fatalf("Error SELECT: %v", err)
+	}
+
+	var toCmp = new(big.Int)
+	toCmp, _ = toCmp.SetString("-170141183460469231731687303715884105727", 10)
+
+	if i128.Cmp(toCmp) != 0 {
+		t.Fatalf("Negative INT128 Error: %v", i128)
+	}
+
+	conn.Close()
+}
+
 func TestLegacyAuthWireCrypt(t *testing.T) {
 	test_dsn := GetTestDSN("test_legacy_auth_")
 	var n int

xsqlvar.go

@@ -463,6 +463,20 @@ func (x *xSQLVAR) value(raw_value []byte, timezone string, charset string) (v in
 			v = i64
 		}
 	case SQL_TYPE_INT128:
+		var isNegative bool
+
+		// when raw_value[0] is > 127, then subtract 255 in every index
+		if raw_value[0] > 127 {
+			for i := range raw_value {
+				if raw_value[i] < 255 {
+					raw_value[i] = 255 - raw_value[i]
+				} else {
+					raw_value[i] -= 255
+				}
+			}
+			isNegative = true
+		}
+
 		// reverse
 		for i, j := 0, len(raw_value)-1; i < j; i, j = i+1, j-1 {
 			raw_value[i], raw_value[j] = raw_value[j], raw_value[i]
@@ -489,6 +503,12 @@ func (x *xSQLVAR) value(raw_value []byte, timezone string, charset string) (v in
 			// add to x
 			x.Add(x, xx)
 		}
+
+		// when negative, add 1 and mul -1
+		if isNegative {
+			x.Add(x, big.NewInt(1))
+			x.Mul(x, big.NewInt(-1))
+		}
 		v = x
 	case SQL_TYPE_DATE:
 		v = x.parseDate(raw_value, timezone)