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/*
Derived from source code of TrueCrypt 7.1a, which is
Copyright (c) 2008-2012 TrueCrypt Developers Association and which is governed
by the TrueCrypt License 3.0.
Modifications and additions to the original source code (contained in this file)
and all other portions of this file are Copyright (c) 2013-2017 IDRIX
and are governed by the Apache License 2.0 the full text of which is
contained in the file License.txt included in VeraCrypt 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);
}
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