diff options
| author | Aleksandar Markovic <aleksandar.markovic@imgtec.com> | 2017-08-21 14:24:48 +0200 |
|---|---|---|
| committer | Ralf Baechle <ralf@linux-mips.org> | 2017-08-29 15:21:56 +0200 |
| commit | 3ec404d88cefbe42d96a46f20f554f8366d64c33 (patch) | |
| tree | 0be1976f5b627283eac1702b54b3645da2dacca9 /MAINTAINERS | |
| parent | 1ff8560ac9db1cbffcd700b70e1661f2fcc2e5d7 (diff) | |
MIPS: math-emu: RINT.<D|S>: Fix several problems by reimplementation
Reimplement RINT.<D|S> kernel emulation so that all RINT.<D|S>
specifications are met.
For the sake of simplicity, let's analyze RINT.S only. Prior to
this patch, RINT.S emulation was essentially implemented as (in
pseudocode) <output> = ieee754sp_flong(ieee754sp_tlong(<input>)),
where ieee754sp_tlong() and ieee754sp_flong() are functions
providing conversion from double to integer, and from integer
to double, respectively. On surface, this implementation looks
correct, but actually fails in many cases. Following problems
were detected:
1. NaN and infinity cases will not be handled properly. The
function ieee754sp_flong() never returns NaN nor infinity.
2. For RINT.S, for all inputs larger than LONG_MAX, and smaller
than FLT_MAX, the result will be wrong, and the overflow
exception will be erroneously set. A similar problem for
negative inputs exists as well.
3. For some rounding modes, for some negative inputs close to zero,
the return value will be zero, and should be -zero. This is
because ieee754sp_flong() never returns -zero.
This patch removes the problems above by implementing dedicated
functions for RINT.<D|S> emulation.
The core of the new function functionality is adapted version of
the core of the function ieee754sp_tlong(). However, there are many
details that are implemented to match RINT.<D|S> specification. It
should be said that the functionality of ieee754sp_tlong() actually
closely corresponds to CVT.L.S instruction, and it is used while
emulating CVT.L.S. However, RINT.S and CVT.L.S instructions differ
in many aspects. This patch fulfills missing support for RINT.<D|S>.
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>
Cc: David S. Miller <davem@davemloft.net>
Cc: Douglas Leung <douglas.leung@imgtec.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Hans Verkuil <hans.verkuil@cisco.com>
Cc: James Hogan <james.hogan@imgtec.com>
Cc: Maciej W. Rozycki <macro@imgtec.com>
Cc: Masahiro Yamada <yamada.masahiro@socionext.com>
Cc: Mauro Carvalho Chehab <mchehab@kernel.org>
Cc: Paul Burton <paul.burton@imgtec.com>
Cc: Petar Jovanovic <petar.jovanovic@imgtec.com>
Cc: Raghu Gandham <raghu.gandham@imgtec.com>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/17141/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Diffstat (limited to 'MAINTAINERS')
| -rw-r--r-- | MAINTAINERS | 7 |
1 files changed, 7 insertions, 0 deletions
diff --git a/MAINTAINERS b/MAINTAINERS index 63102bac3c45..31d4274efb06 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -8802,6 +8802,13 @@ F: arch/mips/include/asm/mach-loongson32/ F: drivers/*/*loongson1* F: drivers/*/*/*loongson1* +MIPS RINT INSTRUCTION EMULATION +M: Aleksandar Markovic <aleksandar.markovic@imgtec.com> +L: linux-mips@linux-mips.org +S: Supported +F: arch/mips/math-emu/sp_rint.c +F: arch/mips/math-emu/dp_rint.c + MIROSOUND PCM20 FM RADIO RECEIVER DRIVER M: Hans Verkuil <hverkuil@xs4all.nl> L: linux-media@vger.kernel.org |