Question

I am writing a program in 16 bit Turbo C++ version 3.0 based on partial Assembly and C code. I have to use the local variables of C code in assembly block. I have debug the following code in Borland C++ 5 and MS VC++ 6. It works fine but these compilers are 32 bit therefore I have to do this in Turbo C. In Turbo C++ it displays an Error: “Invalid combination of opcode and oprends” the code is:

void AssignPixel (int X,int Y,int R,int G, int B )
{
_asm {
mov dx, 0x3c8
mov al, 4
out dx, al
inc dx
mov al, R   // ERROR
out dx, al
mov al, G   // ERROR
out dx, al
mov al, B   // ERROR
out dx, al

     mov ah , 0x0c 
     mov al , 4    
     mov cx , X  // ERROR
     mov dx , Y  // ERROR
     int       0x10 
}

Is there any way to use Variables with assembly code. Code Sample will be appreciated.

Answer 1

You can’t do these most likely because the sizes of the registers and variables don’t match (8-bit vs 16-bit):

mov al, R
mov al, G
mov al, B

And here the assembler probably expects different syntax:

mov cx, X
mov dx, Y

Try these instead:

mov al, byte ptr [R] ; I don't remember if the brackets are required here
mov cx, [X]