On Mon, 21 Aug 2006, Igor Kovalenko wrote:
> On 8/21/06, malc <[EMAIL PROTECTED]> wrote:
>>
>> On Mon, 21 Aug 2006, Igor Kovalenko wrote:
>>
>> <snip>
>>
>> > Right. Here is the real one with correct case labels.
>>
>> Sorry, forgot to mention that atop of the hex/bin problem the code also
>> suffers from lack of proper 16/64 bit modrm decoding.
>
>
> seems to me that 16 and 64 bit cases does not apply here
Well, quick experiment in vm86 environment suggests that i'm right at
least for 16bit case.
<moo.asm>
xor ax, ax
int 16h
db 0xf, 0x19, 5, 0xde, 0xad
db 0xf, 0x19, 5, 0xbe, 0xef
mov ah, 9
mov dx, erm
add dx, 0x100
int 21h
xor ax, ax
int 16h
ret
erm db "moo$"
</moo.asm>
nasm -o moo.com moo.asm
dosemu moo.com
64bit case should be investigated by someone who possesses 64bit OS.
Here is the updated patch, should implement 16/32/64 modes according to public intel docs.
Operand size is taken from DisassContext->dflag which is set beforehand; I assume it is decoded correctly wrt appropriate instruction prefixes.
--
Kind Regards,
Igor V. Kovalenko
Index: target-i386/translate.c
===================================================================
RCS file: /cvsroot/qemu/qemu/target-i386/translate.c,v
retrieving revision 1.59
diff -u -r1.59 translate.c
--- target-i386/translate.c 10 Jul 2006 19:53:04 -0000 1.59
+++ target-i386/translate.c 30 Aug 2006 19:19:45 -0000
@@ -1615,6 +1615,63 @@
*offset_ptr = disp;
}
+static void gen_nop_modrm(DisasContext *s, int modrm)
+{
+ int rm, mod;
+ rm = modrm & 7;
+ mod = (modrm >> 6) & 3;
+
+ switch (s->dflag)
+ {
+ case 0:
+ /* 16 bit */
+ if (mod == 0 && rm == 6)
+ {
+ /* 16 bit data follows */
+ s->pc += 2;
+ }
+ else if (mod < 3)
+ {
+ /* 0, 8 or 16 bit data follows */
+ s->pc += mod;
+ }
+ break;
+
+ case 2:
+ /* 64 bit, modr/m size does not change, use 32 bit case */
+ case 1:
+ /*32 bit*/
+ if (mod == 0 && rm == 5)
+ {
+ /* 32 bit data follows */
+ s->pc += 4;
+ }
+ else
+ {
+ if (mod < 3 && rm == 4)
+ {
+ /* SIB byte follows */
+ s->pc += 1;
+ }
+
+ if (mod == 1)
+ {
+ /* 8 bit data follows */
+ s->pc += 1;
+ }
+ else if (mod == 1)
+ {
+ /* 32 bit data follows */
+ s->pc += 4;
+ }
+ }
+ break;
+ default:
+ /* undefined */
+ break;
+ }
+}
+
/* used for LEA and MOV AX, mem */
static void gen_add_A0_ds_seg(DisasContext *s)
{
@@ -5792,9 +5849,15 @@
/* nothing more to do */
break;
default:
- goto illegal_op;
+ gen_nop_modrm(s, modrm);
+ break;
}
break;
+ case 0x119 ... 0x11f:
+ /* multi-byte noop */
+ modrm = ldub_code(s->pc++);
+ gen_nop_modrm(s, modrm);
+ break;
case 0x120: /* mov reg, crN */
case 0x122: /* mov crN, reg */
if (s->cpl != 0) {
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