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realemu: implement CMPS and SCAS instructions

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This commit is contained in:
cinap_lenrek 2011-04-22 13:06:55 +00:00
parent fcf2f14760
commit e003d49fe1
1 changed files with 81 additions and 2 deletions
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83
sys/src/cmd/aux/realemu/xec.c
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@ -1040,7 +1040,84 @@ opstos(Cpu *cpu, Inst *i)
}
aw(areg(cpu, i->alen, RDI), d->off);
if(cx)
aw(cx, 0);
aw(cx, c);
}
static int
repcond(Cpu *cpu, int rep)
{
switch(rep){
case OREPNE:
return (cpu->reg[RFL] & ZF) == 0;
case OREPE:
default:
return !rep || (cpu->reg[RFL] & ZF) != 0;
}
}
static void
opscas(Cpu *cpu, Inst *i)
{
Iarg *cx, *s;
ulong c;
long a;
int n;
s = adup(i->a1);
n = s->len;
if(cpu->reg[RFL] & DF)
n = -n;
if(i->rep){
cx = areg(cpu, i->alen, RCX);
c = ar(cx);
} else {
cx = nil;
c = 1;
}
a = ars(i->a2);
while(c){
sub(cpu->reg + RFL, a, ars(s), 0, s->len*8);
s->off += n;
c--;
if(repcond(cpu, i->rep))
break;
}
aw(areg(cpu, i->alen, RDI), s->off);
if(cx)
aw(cx, c);
}
static void
opcmps(Cpu *cpu, Inst *i)
{
Iarg *cx, *s, *d;
ulong c;
int n;
d = adup(i->a1);
s = adup(i->a2);
n = s->len;
if(cpu->reg[RFL] & DF)
n = -n;
if(i->rep){
cx = areg(cpu, i->alen, RCX);
c = ar(cx);
} else {
cx = nil;
c = 1;
}
while(c){
sub(cpu->reg + RFL, ars(s), ars(d), 0, s->len*8);
s->off += n;
d->off += n;
c--;
if(repcond(cpu, i->rep))
break;
}
aw(areg(cpu, i->alen, RDI), d->off);
aw(areg(cpu, i->alen, RSI), s->off);
if(cx)
aw(cx, c);
}
static void
@ -1159,8 +1236,10 @@ static void (*exctab[NUMOP])(Cpu *cpu, Inst*) = {
[OCPUID] = opcpuid,
[OMOVS] = opmovs,
[OSTOS] = opstos,
[OLODS] = oplods,
[OSTOS] = opstos,
[OSCAS] = opscas,
[OCMPS] = opcmps,
[OIN] = opin,
[OOUT] = opout,