Inline Assembly Question

tjt · 08-06-2004, 11:05 AM

Here is what I have written:

static DWORD lvalue;

asm volatile (
"inl %%dx, %%eax\n\t"
: "=a" (lvalue)
: "d" (port)
: "memory"
);

But when I step through with gdb I always see that eax and lvalue equal 0xffff instead of 0xffffffff. Why aren't they showing up as DWORDs instead of WORDs?

tuxfood · 08-07-2004, 11:18 PM

hi...

with the knowlegde that i have abt assembly..isn't eax supposed to be a 32 bit reg.. (0xffff -----> takes 32 bits)

so maybe that's the reason

isn't it????

tuxfood

frob23 · 08-07-2004, 11:50 PM

0xffff takes 16 bits (0b1111111111111111) not 32. And eax should be 32 bits long.

Just a thought but dx is only 16 bits. Ugh, too bad most of my assembly knowledge comes from when I was still using DOS.

jinksys · 08-08-2004, 04:38 AM

Only thing I could think would be wrong is the static DWORD lvalue; code.
Are you sure DWORD is actually a double word? Can you post the code
that typedef's it?