From d8c68ed00351e359142500d3e15ae82ed3d9bcc6 Mon Sep 17 00:00:00 2001
From: belliash <belliash@codingworkshop.eu.org>
Date: Wed, 8 Feb 2023 16:33:57 +0100
Subject: [PATCH] Add endian conversion routines

---
 sdk/xtdk/rtlfuncs.h     | 12 +++++++
 xtoskrnl/CMakeLists.txt |  1 +
 xtoskrnl/rtl/byteswap.c | 72 +++++++++++++++++++++++++++++++++++++++++
 3 files changed, 85 insertions(+)
 create mode 100644 xtoskrnl/rtl/byteswap.c

diff --git a/sdk/xtdk/rtlfuncs.h b/sdk/xtdk/rtlfuncs.h
index 18895c4..bab140e 100644
--- a/sdk/xtdk/rtlfuncs.h
+++ b/sdk/xtdk/rtlfuncs.h
@@ -91,6 +91,18 @@ RtlStringToWideString(OUT PWCHAR Destination,
                       IN CONST PUCHAR *Source,
                       IN SIZE_T Length);
 
+XTFASTCALL
+ULONG
+RtlUlongByteSwap(IN ULONG Source);
+
+XTFASTCALL
+ULONGLONG
+RtlUlonglongByteSwap(IN ULONGLONG Source);
+
+XTFASTCALL
+USHORT
+RtlUshortByteSwap(IN USHORT Source);
+
 XTCDECL
 INT
 RtlWideStringCompare(IN CONST PWCHAR String1,
diff --git a/xtoskrnl/CMakeLists.txt b/xtoskrnl/CMakeLists.txt
index f296af1..2137316 100644
--- a/xtoskrnl/CMakeLists.txt
+++ b/xtoskrnl/CMakeLists.txt
@@ -18,6 +18,7 @@ list(APPEND XTOSKRNL_SOURCE
     ${XTOSKRNL_SOURCE_DIR}/ke/globals.c
     ${XTOSKRNL_SOURCE_DIR}/ke/krnlinit.c
     ${XTOSKRNL_SOURCE_DIR}/ke/${ARCH}/krnlinit.c
+    ${XTOSKRNL_SOURCE_DIR}/rtl/byteswap.c
     ${XTOSKRNL_SOURCE_DIR}/rtl/memory.c
     ${XTOSKRNL_SOURCE_DIR}/rtl/plist.c
     ${XTOSKRNL_SOURCE_DIR}/rtl/string.c
diff --git a/xtoskrnl/rtl/byteswap.c b/xtoskrnl/rtl/byteswap.c
new file mode 100644
index 0000000..954c89b
--- /dev/null
+++ b/xtoskrnl/rtl/byteswap.c
@@ -0,0 +1,72 @@
+/**
+ * PROJECT:         ExectOS
+ * COPYRIGHT:       See COPYING.md in the top level directory
+ * FILE:            xtoskrnl/rtl/byteswap.c
+ * DESCRIPTION:     Endian conversion routines
+ * DEVELOPERS:      Rafal Kupiec <belliash@codingworkshop.eu.org>
+ */
+
+#include <xtos.h>
+
+
+/**
+ * This routine converts endianness on 32bit value.
+ *
+ * @param Source
+ *        Supplies a value to swap bytes.
+ *
+ * @return Swapped 32bit value.
+ *
+ * @since NT 4.0
+ */
+XTFASTCALL
+ULONG
+RtlUlongByteSwap(IN ULONG Source)
+{
+    return (ULONG)(((Source >> 24) & 0x000000FF) |
+                   ((Source >> 8)  & 0x0000FF00) |
+                   ((Source << 8)  & 0x00FF0000) |
+                   ((Source << 24) & 0xFF000000));
+}
+
+/**
+ * This routine converts endianness on 64bit value.
+ *
+ * @param Source
+ *        Supplies a value to swap bytes.
+ *
+ * @return Swapped 64bit value.
+ *
+ * @since NT 4.0
+ */
+XTFASTCALL
+ULONGLONG
+RtlUlonglongByteSwap(IN ULONGLONG Source)
+{
+    return (ULONGLONG)(((Source >> 56) & 0x00000000000000FF) |
+                       ((Source >> 40) & 0x000000000000FF00) |
+                       ((Source >> 24) & 0x0000000000FF0000) |
+                       ((Source >> 8)  & 0x00000000FF000000) |
+                       ((Source << 8)  & 0x000000FF00000000) |
+                       ((Source << 24) & 0x0000FF0000000000) |
+                       ((Source << 40) & 0x00FF000000000000) |
+                       ((Source << 56) & 0xFF00000000000000));
+}
+
+/**
+ * This routine converts endianness on 16bit value.
+ *
+ * @param Source
+ *        Supplies a value to swap bytes.
+ *
+ * @return Swapped 16bit value.
+ *
+ * @since NT 4.0
+ */
+XTFASTCALL
+USHORT
+RtlUshortByteSwap(IN USHORT Source)
+{
+    return (USHORT)(((Source >> 8) & 0x00FF) |
+                    ((Source << 8) & 0xFF00));
+}