Endian conversion: move to platform.h and platform/endian*.c

Starting to move the platform dependent code to platform/ and provide
the abstraction through the platform.h header.

Change-Id: I35640282d451960f2a329ae24339ec05dbae6d30
Signed-off-by: Thomas Heijligen <thomas.heijligen@secunet.com>
Original-Reviewed-on: https://review.coreboot.org/c/flashrom/+/62899
Original-Reviewed-by: Nico Huber <nico.h@gmx.de>
Reviewed-on: https://review.coreboot.org/c/flashrom-stable/+/72316
Reviewed-by: Nico Huber <nico.h@gmx.de>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
diff --git a/platform/endian_big.c b/platform/endian_big.c
new file mode 100644
index 0000000..5d65500
--- /dev/null
+++ b/platform/endian_big.c
@@ -0,0 +1,42 @@
+/*
+ * This file is part of the flashrom project.
+ *
+ * Copyright (C) 2022 secunet Security Networks AG
+ * (written by Thomas Heijligen <thomas.heijligen@secunet.com)
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#include "../platform.h"
+
+/* convert cpu native endian to little endian */
+___return_swapped(cpu_to_le, 8)
+___return_swapped(cpu_to_le, 16)
+___return_swapped(cpu_to_le, 32)
+___return_swapped(cpu_to_le, 64)
+
+/* convert cpu native endian to big endian */
+___return_same(cpu_to_be, 8)
+___return_same(cpu_to_be, 16)
+___return_same(cpu_to_be, 32)
+___return_same(cpu_to_be, 64)
+
+/* convert little endian to cpu native endian */
+___return_swapped(le_to_cpu, 8)
+___return_swapped(le_to_cpu, 16)
+___return_swapped(le_to_cpu, 32)
+___return_swapped(le_to_cpu, 64)
+
+/* convert big endian to cpu native endian */
+___return_same(be_to_cpu, 8)
+___return_same(be_to_cpu, 16)
+___return_same(be_to_cpu, 32)
+___return_same(be_to_cpu, 64)