windows: _win.v => windows.v

vlib/crypto/rand/rand_windows.v

@@ -0,0 +1,24 @@
+// Copyright (c) 2019 Alexander Medvednikov. All rights reserved.
+// Use of this source code is governed by an MIT license
+// that can be found in the LICENSE file.
+
+module rand
+
+#flag windows -Llibraries/bcrypt
+#flag windows -lbcrypt
+#include <bcrypt.h>
+
+const (
+	STATUS_SUCCESS                  = 0x00000000
+	BCRYPT_USE_SYSTEM_PREFERRED_RNG = 0x00000002
+)
+
+pub fn read(bytes_needed int) ?[]byte {	
+	mut buffer := malloc(bytes_needed)
+	// use BCRYPT_USE_SYSTEM_PREFERRED_RNG because we passed null as algo
+	status := C.BCryptGenRandom(0, buffer, bytes_needed, BCRYPT_USE_SYSTEM_PREFERRED_RNG)
+	if status != STATUS_SUCCESS {
+		return ReadError
+	}
+	return c_array_to_bytes_tmp(bytes_needed, buffer)
+}