Re: [Tinycc-devel] lcall invalid hex code

[Michael Matz]

Hi,

On Mon, 2 May 2016, Michael Matz wrote:

> > ALT(DEF_ASM_OP2(lcall, 0x9a, 0, 0, OPT_IM16, OPT_IM32))
> > -ALT(DEF_ASM_OP1(lcall, 0xff, 3, 0, OPT_EA))
> > +ALT(DEF_ASM_OP1(lcall, 0xff1f, 3, 0, OPT_EA))
> > ALT(DEF_ASM_OP2(ljmp, 0xea, 0, 0, OPT_IM16, OPT_IM32))
> > ALT(DEF_ASM_OP1(ljmp, 0xff, 5, 0, OPT_EA))
>
> You don't say what exactly you want to fix, but whatever it is, the patch is 
> incorrect.  'lcall' is no two-byte opcode (those start with 0x0f), but rather 
> the opcode is 0xff and the sub-opcode is in the mod/rm byte (aka. group #5 
> [1]).  It's sub-opcode 3, hence correct above.
>
> If anything the decoding of the above table in i386-asm.c is wrong, but I 
> can't say without knowing what the problem is.

With your followup I now know your problem.  The mod/rm byte was simply 
missing from the encoding.  I've corrected this in mob.


Ciao,
Michael.