c: TestLongDouble

c/c_test.go

@@ -0,0 +1,31 @@
+/*
+ * Copyright (c) 2026 The XGo Authors (xgo.dev). All rights reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package c_test
+
+import (
+	"testing"
+	"unsafe"
+
+	"github.com/goplus/lib/c"
+)
+
+func TestLongDouble(t *testing.T) {
+	var ld c.LongDouble
+	if c.LongDoubleSize != unsafe.Sizeof(ld) {
+		t.Fatalf("unexpected LongDoubleSize: %d", c.LongDoubleSize)
+	}
+}

c/ldobule_float64.go → c/ldouble_float64.go

@@ -1,7 +1,7 @@
 //go:build (windows && !(mingw && (amd64 || 386))) || (darwin && arm64) || arm || mips || mipsle || ((ppc64 || ppc64le) && !linux)
 
 /*
- * Copyright (c) 2024 The XGo Authors (xgo.dev). All rights reserved.
+ * Copyright (c) 2026 The XGo Authors (xgo.dev). All rights reserved.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.

c/ldouble_x87.go

@@ -0,0 +1,35 @@
+//go:build amd64 && (!windows || mingw)
+
+/*
+ * Copyright (c) 2026 The XGo Authors (xgo.dev). All rights reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package c
+
+// LongDouble is the x87 80-bit extended precision format, stored in 16 bytes
+// (10 significant bytes + 6 bytes padding). Applies to x86-64 on
+// Linux/macOS/BSD and MinGW on Windows.
+//
+// The C ABI requires 16-byte alignment, which Go cannot express (Go caps
+// alignment at 8); the zero-size field below gives 8-byte alignment at most.
+// When embedding LongDouble in a mirrored C struct, add explicit padding so
+// the field offset is a multiple of 16.
+type LongDouble struct {
+	_    [0]uint64
+	Data [16]byte
+}
+
+// LongDoubleSize is sizeof(long double) in bytes on this target.
+const LongDoubleSize = 16