Inline Assembly with Visual C++ 2008

[aurelcly]

Good Afternoon I have an compilation error in my code with inline assembly.I want to get IVT(Interrupt Vector Table)Address using VC++ 2008 I have "Illegal 16 bits instruction" with line MOV AX,ES:[BX]. Can you help me please. #define WORD unsigned short WORD address; __asm { push ES MOV AX,0 MOV ES,AX MOV BX,address MOV AX,ES:[BX] // Compilation Error } Thank you.

[Luc Pattyn]

AFAIK on recent Windows platforms assembly instructions operate by default on either 8-bit or 32-bit quantities, not 16-bit. And the 32-bit version of the CPU registers are called EAX, EBX, etc. If you really want a 16-bit operation, you need a prefix instruction byte, I don't know what syntax it takes though. :)

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[Michel Godfroid]

Yes, I remember MS-DOS fondly. The Interrupt Vector Table was sitting at 0000:0000 to 0000:0400. Sorry to disappoint you, but things have changed a bit in the last 20 years or so. I assume you're not programming for WinMe :laugh: (I think that was the last operating system that supported this) or the 16-bit VDM (Which was probably disposed of in Windows Vista??) If you are, try to lay hands on an old copy of Visual C++. I think the GNU C compiler can still generate 16 bit code for real mode. Have a look at this: Get interrupt vector information in Windows[^] (This is probably only valid for 32-bit versions of Windows, the ULONG's look suspiciously short, but you'll probably find all the info in the latest and greatest DDK -- too lazy to look it up). Oh, yes, before you ask (I just know this is coming): you cannot change this IDT, except in a device driver.