Patchwork x86: fix daa opcode for al register values higher than 0xf9

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Submitter Boris Figovsky
Date Aug. 30, 2011, 7 a.m.
Message ID <4e5c8d01.05cbe30a.22c4.ffffe8ac@mx.google.com>
Download mbox | patch
Permalink /patch/112183/
State New
Headers show

Comments

Boris Figovsky - Aug. 30, 2011, 7 a.m.
The second if statement should consider the original al register value,
and not the new one.

Signed-off-by: Boris Figovsky <boris.figovksy@ravellosystems.com>
---
 target-i386/op_helper.c |    6 +++---
 1 files changed, 3 insertions(+), 3 deletions(-)
Peter Maydell - Aug. 30, 2011, 11:18 a.m.
On 30 August 2011 08:00, Boris Figovsky
<boris.figovsky@ravellosystems.com> wrote:
> The second if statement should consider the original al register value,
> and not the new one.

Reviewed-by: Peter Maydell <peter.maydell@linaro.org>

(It took me some time to convince myself that the line
   CF <- old_CF or (Carry from AL <- AL + 6)
in the Intel architecture manual is actually redundant; the
AMD docs are much clearer here...)

-- PMM
Stefan Hajnoczi - Sept. 2, 2011, 10:09 a.m.
On Tue, Aug 30, 2011 at 10:00:55AM +0300, Boris Figovsky wrote:
> The second if statement should consider the original al register value,
> and not the new one.
> 
> Signed-off-by: Boris Figovsky <boris.figovksy@ravellosystems.com>
> ---
>  target-i386/op_helper.c |    6 +++---
>  1 files changed, 3 insertions(+), 3 deletions(-)

Thanks, applied to the trivial patches tree:
http://repo.or.cz/w/qemu/stefanha.git/shortlog/refs/heads/trivial-patches

Stefan

Patch

diff --git a/target-i386/op_helper.c b/target-i386/op_helper.c
index 1bbc3b5..1fc248f 100644
--- a/target-i386/op_helper.c
+++ b/target-i386/op_helper.c
@@ -1970,20 +1970,20 @@  void helper_aas(void)
 
 void helper_daa(void)
 {
-    int al, af, cf;
+    int old_al, al, af, cf;
     int eflags;
 
     eflags = helper_cc_compute_all(CC_OP);
     cf = eflags & CC_C;
     af = eflags & CC_A;
-    al = EAX & 0xff;
+    old_al = al = EAX & 0xff;
 
     eflags = 0;
     if (((al & 0x0f) > 9 ) || af) {
         al = (al + 6) & 0xff;
         eflags |= CC_A;
     }
-    if ((al > 0x9f) || cf) {
+    if ((old_al > 0x99) || cf) {
         al = (al + 0x60) & 0xff;
         eflags |= CC_C;
     }