From 3cb7fdea950dd2d0377f0d9ad8a88fcb7c48b842 Mon Sep 17 00:00:00 2001
From: Jedidiah Barber <contact@jedbarber.id.au>
Date: Wed, 14 Jul 2021 11:27:03 +1200
Subject: Initial mirror commit

---
 Boot/Windows/BootMemory.cpp | 82 +++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 82 insertions(+)
 create mode 100644 Boot/Windows/BootMemory.cpp

(limited to 'Boot/Windows/BootMemory.cpp')

diff --git a/Boot/Windows/BootMemory.cpp b/Boot/Windows/BootMemory.cpp
new file mode 100644
index 0000000..6c0ff9d
--- /dev/null
+++ b/Boot/Windows/BootMemory.cpp
@@ -0,0 +1,82 @@
+/*
+ Copyright (c) 2008 TrueCrypt Developers Association. All rights reserved.
+
+ Governed by the TrueCrypt License 3.0 the full text of which is contained in
+ the file License.txt included in TrueCrypt binary and source code distribution
+ packages.
+*/
+
+#include "BootDefs.h"
+#include "BootMemory.h"
+
+static uint32 MemoryMapContValue;
+
+static bool GetMemoryMapEntry (BiosMemoryMapEntry &entry)
+{
+	static const uint32 function = 0x0000E820UL;
+	static const uint32 magic = 0x534D4150UL;
+	static const uint32 bufferSize = sizeof (BiosMemoryMapEntry);
+
+	bool carry = false;
+	uint32 resultMagic;
+	uint32 resultSize;
+
+	__asm
+	{
+		push es
+
+		lea di, function
+		TC_ASM_MOV_EAX_DI
+		lea di, MemoryMapContValue
+		TC_ASM_MOV_EBX_DI
+		lea di, bufferSize
+		TC_ASM_MOV_ECX_DI
+		lea di, magic
+		TC_ASM_MOV_EDX_DI
+		lea di, MemoryMapContValue
+		TC_ASM_MOV_DI_ECX
+
+		// Use alternative segment to prevent memory corruption caused by buggy BIOSes
+		push TC_BOOT_LOADER_ALT_SEGMENT
+		pop es
+		mov di, 0
+		
+		int 0x15
+		jnc no_carry
+		mov carry, true
+	no_carry:
+
+		lea di, resultMagic
+		TC_ASM_MOV_DI_EAX
+		lea di, MemoryMapContValue
+		TC_ASM_MOV_DI_EBX
+		lea di, resultSize
+		TC_ASM_MOV_DI_ECX
+
+		pop es
+	}
+
+	CopyMemory (TC_BOOT_LOADER_ALT_SEGMENT, 0, &entry, sizeof (entry));
+
+	// BIOS may set CF at the end of the list
+	if (carry)
+		MemoryMapContValue = 0;
+
+	return resultMagic == magic && resultSize == bufferSize;
+}
+
+
+bool GetFirstBiosMemoryMapEntry (BiosMemoryMapEntry &entry)
+{
+	MemoryMapContValue = 0;
+	return GetMemoryMapEntry (entry);
+}
+
+
+bool GetNextBiosMemoryMapEntry (BiosMemoryMapEntry &entry)
+{
+	if (MemoryMapContValue == 0)
+		return false;
+
+	return GetMemoryMapEntry (entry);
+}
-- 
cgit