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SubjectRe: [PATCH v3 08/16] MIPS: math-emu: <MAXA|MINA>.<D|S>: Fix cases of input values with opposite signs
On Fri, Jul 21, 2017 at 04:09:06PM +0200, Aleksandar Markovic wrote:
> From: Aleksandar Markovic <aleksandar.markovic@imgtec.com>
>
> Fix the value returned by <MAXA|MINA>.<D|S>, if inputs are normal fp
> numbers of the same absolute value, but opposite signs.
>
> The relevant example:
>
> MAXA.S fd,fs,ft:
> If fs contains -3, and ft contains +3, fd is going to contain +3
> (without this patch, it used to contain -3).

I think its worth mentioning also that for MINA.*, it returns the
negative one when the absolute values are equal (The phrase "For equal
absolute values, returns the smallest positive argument" in the manual
is a bit ambiguous IMO, so I ended up checking what I6500 did).

>

Usual fixes/stable thing.

> Signed-off-by: Miodrag Dinic <miodrag.dinic@imgtec.com>
> Signed-off-by: Goran Ferenc <goran.ferenc@imgtec.com>
> Signed-off-by: Aleksandar Markovic <aleksandar.markovic@imgtec.com>

Reviewed-by: James Hogan <james.hogan@imgtec.com>

Thanks
James

> ---
> arch/mips/math-emu/dp_fmax.c | 8 ++++++--
> arch/mips/math-emu/dp_fmin.c | 6 +++++-
> arch/mips/math-emu/sp_fmax.c | 8 ++++++--
> arch/mips/math-emu/sp_fmin.c | 6 +++++-
> 4 files changed, 22 insertions(+), 6 deletions(-)
>
> diff --git a/arch/mips/math-emu/dp_fmax.c b/arch/mips/math-emu/dp_fmax.c
> index a0175cc..860b43f9 100644
> --- a/arch/mips/math-emu/dp_fmax.c
> +++ b/arch/mips/math-emu/dp_fmax.c
> @@ -224,7 +224,11 @@ union ieee754dp ieee754dp_fmaxa(union ieee754dp x, union ieee754dp y)
> return y;
>
> /* Compare mantissa */
> - if (xm <= ym)
> + if (xm < ym)
> return y;
> - return x;
> + else if (xm > ym)
> + return x;
> + else if (xs == 0)
> + return x;
> + return y;
> }
> diff --git a/arch/mips/math-emu/dp_fmin.c b/arch/mips/math-emu/dp_fmin.c
> index 074a858..73d85e4 100644
> --- a/arch/mips/math-emu/dp_fmin.c
> +++ b/arch/mips/math-emu/dp_fmin.c
> @@ -224,7 +224,11 @@ union ieee754dp ieee754dp_fmina(union ieee754dp x, union ieee754dp y)
> return x;
>
> /* Compare mantissa */
> - if (xm <= ym)
> + if (xm < ym)
> + return x;
> + else if (xm > ym)
> + return y;
> + else if (xs == 1)
> return x;
> return y;
> }
> diff --git a/arch/mips/math-emu/sp_fmax.c b/arch/mips/math-emu/sp_fmax.c
> index 15825db..fec7f64 100644
> --- a/arch/mips/math-emu/sp_fmax.c
> +++ b/arch/mips/math-emu/sp_fmax.c
> @@ -224,7 +224,11 @@ union ieee754sp ieee754sp_fmaxa(union ieee754sp x, union ieee754sp y)
> return y;
>
> /* Compare mantissa */
> - if (xm <= ym)
> + if (xm < ym)
> return y;
> - return x;
> + else if (xm > ym)
> + return x;
> + else if (xs == 0)
> + return x;
> + return y;
> }
> diff --git a/arch/mips/math-emu/sp_fmin.c b/arch/mips/math-emu/sp_fmin.c
> index f1418f7..74780bc 100644
> --- a/arch/mips/math-emu/sp_fmin.c
> +++ b/arch/mips/math-emu/sp_fmin.c
> @@ -225,7 +225,11 @@ union ieee754sp ieee754sp_fmina(union ieee754sp x, union ieee754sp y)
> return x;
>
> /* Compare mantissa */
> - if (xm <= ym)
> + if (xm < ym)
> + return x;
> + else if (xm > ym)
> + return y;
> + else if (xs == 1)
> return x;
> return y;
> }
> --
> 2.7.4
>
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