[PATCH] parisc: test off by one in sgl_frem() and dbl_frem()

[PATCH] parisc: test off by one in sgl_frem() and dbl_frem()

[Roel Kluin]

With `while (stepcount-- > 0)' stepcount reaches -1 after the loop.

Signed-off-by: Roel Kluin <roel.kluin@gmail.com>
---
 arch/parisc/math-emu/dfrem.c |    2 +-
 arch/parisc/math-emu/sfrem.c |    2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

Unless I am missing something?

diff --git a/arch/parisc/math-emu/dfrem.c b/arch/parisc/math-emu/dfrem.c
index b983785..3283445 100644
--- a/arch/parisc/math-emu/dfrem.c
+++ b/arch/parisc/math-emu/dfrem.c
@@ -234,7 +234,7 @@ dbl_frem (dbl_floating_point * srcptr1, dbl_floating_point * srcptr2,
 		Dbl_subtract(opnd1p1,opnd1p2,opnd2p1,opnd2p2,opnd1p1,opnd1p2);
 		roundup = TRUE;
 	}
-	if (stepcount > 0 || Dbl_iszero(opnd1p1,opnd1p2)) {
+	if (stepcount >= 0 || Dbl_iszero(opnd1p1,opnd1p2)) {
 		/* division is exact, remainder is zero */
 		Dbl_setzero_exponentmantissa(resultp1,resultp2);
 		Dbl_copytoptr(resultp1,resultp2,dstptr);
diff --git a/arch/parisc/math-emu/sfrem.c b/arch/parisc/math-emu/sfrem.c
index 3a1b7a3..ad87832 100644
--- a/arch/parisc/math-emu/sfrem.c
+++ b/arch/parisc/math-emu/sfrem.c
@@ -229,7 +229,7 @@ sgl_frem (sgl_floating_point * srcptr1, sgl_floating_point * srcptr2,
 		Sgl_subtract(opnd1,opnd2,opnd1);
 		roundup = TRUE;
 	}
-	if (stepcount > 0 || Sgl_iszero(opnd1)) {
+	if (stepcount >= 0 || Sgl_iszero(opnd1)) {
 		/* division is exact, remainder is zero */
 		Sgl_setzero_exponentmantissa(result);
 		*dstptr = result;

Re: [PATCH] parisc: test off by one in sgl_frem() and dbl_frem()

[John David Anglin]

> With `while (stepcount-- > 0)' stepcount reaches -1 after the loop.
> 
> Signed-off-by: Roel Kluin <roel.kluin@gmail.com>
> ---
>  arch/parisc/math-emu/dfrem.c |    2 +-
>  arch/parisc/math-emu/sfrem.c |    2 +-
>  2 files changed, 2 insertions(+), 2 deletions(-)
> 
> Unless I am missing something?

Are you sure the correct fix isn't to move the decrement of stepcount
into the loop?

Dave
-- 
J. David Anglin                                  dave.anglin@nrc-cnrc.gc.ca
National Research Council of Canada              (613) 990-0752 (FAX: 952-6602)

Re: [PATCH] parisc: test off by one in sgl_frem() and dbl_frem()

[James Bottomley]

On Sun, 2009-12-27 at 14:21 +0100, Roel Kluin wrote:
> With `while (stepcount-- > 0)' stepcount reaches -1 after the loop.

This is true, but seems to be by design

> Signed-off-by: Roel Kluin <roel.kluin@gmail.com>
> ---
>  arch/parisc/math-emu/dfrem.c |    2 +-
>  arch/parisc/math-emu/sfrem.c |    2 +-
>  2 files changed, 2 insertions(+), 2 deletions(-)
> 
> Unless I am missing something?
> 
> diff --git a/arch/parisc/math-emu/dfrem.c b/arch/parisc/math-emu/dfrem.c
> index b983785..3283445 100644
> --- a/arch/parisc/math-emu/dfrem.c
> +++ b/arch/parisc/math-emu/dfrem.c
> @@ -234,7 +234,7 @@ dbl_frem (dbl_floating_point * srcptr1, dbl_floating_point * srcptr2,
>  		Dbl_subtract(opnd1p1,opnd1p2,opnd2p1,opnd2p2,opnd1p1,opnd1p2);
>  		roundup = TRUE;
>  	}
> -	if (stepcount > 0 || Dbl_iszero(opnd1p1,opnd1p2)) {
> +	if (stepcount >= 0 || Dbl_iszero(opnd1p1,opnd1p2)) {
>  		/* division is exact, remainder is zero */
>  		Dbl_setzero_exponentmantissa(resultp1,resultp2);
>  		Dbl_copytoptr(resultp1,resultp2,dstptr);
> diff --git a/arch/parisc/math-emu/sfrem.c b/arch/parisc/math-emu/sfrem.c
> index 3a1b7a3..ad87832 100644
> --- a/arch/parisc/math-emu/sfrem.c
> +++ b/arch/parisc/math-emu/sfrem.c
> @@ -229,7 +229,7 @@ sgl_frem (sgl_floating_point * srcptr1, sgl_floating_point * srcptr2,
>  		Sgl_subtract(opnd1,opnd2,opnd1);
>  		roundup = TRUE;
>  	}
> -	if (stepcount > 0 || Sgl_iszero(opnd1)) {
> +	if (stepcount >= 0 || Sgl_iszero(opnd1)) {
>  		/* division is exact, remainder is zero */
>  		Sgl_setzero_exponentmantissa(result);
>  		*dstptr = result;

Your patch does nothing to the actual execution flow (Sgl_iszero is true
if stepcount == 0) ... what's the point of applying it?

James

Re: [PATCH] parisc: test off by one in sgl_frem() and dbl_frem()

[Roel Kluin]

Op 27-12-09 16:30, James Bottomley schreef:
> On Sun, 2009-12-27 at 14:21 +0100, Roel Kluin wrote:
>> With `while (stepcount-- > 0)' stepcount reaches -1 after the loop.
> 
> This is true, but seems to be by design

>> -	if (stepcount > 0 || Sgl_iszero(opnd1)) {
>> +	if (stepcount >= 0 || Sgl_iszero(opnd1)) {

> 
> Your patch does nothing to the actual execution flow (Sgl_iszero is true
> if stepcount == 0) ... what's the point of applying it?
> 
> James

Ok, please ignore and thanks (also to Dave) for review.

Roel