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* MIPS: math-emu: Add IEEE Std 754-2008 ABS.fmt and NEG.fmt emulationMaciej W. Rozycki2016-01-201-13/+25
| | | | | | | | | | | | | | | | | Implement IEEE Std 754-2008 non-arithmetic ABS.fmt and NEG.fmt emulation wired to the state of the FCSR.ABS2008 bit. In the non-arithmetic mode the sign bit is altered according to the operation requested regardless of the datum encoded in the input operand, no other bits are changed, the resulting bit pattern is written to the output operand and no exception is ever signalled. Signed-off-by: Maciej W. Rozycki <macro@imgtec.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Matthew Fortune <Matthew.Fortune@imgtec.com> Cc: linux-mips@linux-mips.org Cc: linux-kernel@vger.kernel.org Patchwork: https://patchwork.linux-mips.org/patch/11476/ Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
* MIPS: math-emu: Make ABS.fmt and NEG.fmt arithmetic againMaciej W. Rozycki2015-04-081-36/+19
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The ABS.fmt and NEG.fmt instructions have been specified as arithmetic in the MIPS architecture, which in particular implies handling NaN data in the usual way with qNaN bit patterns propagated unchanged and sNaN bit patterns signalling the usual IEEE 754 Invalid Operation exception and quieted by default. A series of changes applied over time to our implementation: c5033d78 [MIPS] ieee754[sd]p_neg workaround cea2be44 MIPS: Fix abs.[sd] and neg.[sd] emulation for NaN operands has led to the current situation where the sign bit is updated according to the operation requested even for NaN inputs. This is according to these commits a workaround so that broken binaries produced by GCC disregarding the properties of these instructions have a chance to work. For sNaN inputs this remains within IEEE Std 754 as the standard leaves the choice of output qNaN bit patterns produced under the default Invalid Operation exception handling for individual sNaN input bit patterns to implementer's discretion, even though it still recommends as much NaN input information to be preserved in NaN outputs. For qNaN inputs however it violates the standard as it requires a qNaN input bit patterns to propagate unchanged to output. This is also unlike real MIPS FPU hardware behaves where sNaN and/or qNaN processing has been fully implemented with no Unimplemented Operation exception signalled. Such hardware propagates any input qNaN bit pattern unchanged. It also quiets any input sNaN bit pattern in an implementer-specific manner, for example the MIPS 74Kf processor returns the default qNaN pattern with the sign bit always clear and the Broadcom SB-1 and BMIPS5000 processors propagate the input sNaN bit pattern with the sign bit unchanged and the quiet bit first cleared in the trailing significand field and then the next lower bit set if clearing the quiet bit left the field with no other bit set. Especially the latter observation indicates the limited usefulness of the workaround as it will cover many hardware configurations, but not all of them, only making it harder to discover such broken binaries that need to be recompiled with GCC told to avoid the use of ABS.fmt and NEG.fmt instructions where non-arithmetic semantics is required by the algorithm used. Revert the damage done by the series of changes then, and take the opportunity to simplify implementation by calling `ieee754dp_sub' and `ieee754dp_add' as required and also the rounding mode set towards -Inf temporarily so that the sign of 0 is correctly handled. Signed-off-by: Maciej W. Rozycki <macro@linux-mips.org> Cc: linux-mips@linux-mips.org Patchwork: https://patchwork.linux-mips.org/patch/9710/ Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
* MIPS: math-emu: Cleanup coding style.Ralf Baechle2014-05-231-7/+1
| | | | | | | | | | | | o Only define variables in the outermost block o One empty line at most o Format comments as per CodingStyle o Update FSF address in licensing term comment o Spell FPU and MIPS in all capitals. o Remove ####-type of lines in comments. o Try to make things a bit most consistent between sp_*.c / dp_*.c files. Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
* MIPS: math-emu: Get rid of the useless parts of exception handling.Ralf Baechle2014-05-231-2/+2
| | | | | | All it really did was throw a printk for no obvious reason. Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
* MIPS: math-emu: Remove unused code.Ralf Baechle2014-05-231-8/+0
| | | | | | Shrinks the FPU emulator by 4528 bytes. Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
* MIPS: math-emu: Inline ieee754dp_finite and ieee754dp_finite().Ralf Baechle2014-05-231-5/+0
| | | | Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
* MIPS: math-emu: Turn macros into functions where possible.Ralf Baechle2014-05-211-5/+5
| | | | Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
* MIPS: math-emu: Get rid of typedefs.Ralf Baechle2014-05-211-5/+5
| | | | Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
* Update broken web addresses in arch directory.Justin P. Mattock2010-10-181-1/+0
| | | | | | | | | | | The patch below updates broken web addresses in the arch directory. Signed-off-by: Justin P. Mattock <justinmattock@gmail.com> Signed-off-by: Maciej W. Rozycki <macro@linux-mips.org> Cc: Finn Thain <fthain@telegraphics.com.au> Cc: Randy Dunlap <rdunlap@xenotime.net> Reviewed-by: Finn Thain <fthain@telegraphics.com.au> Signed-off-by: Jiri Kosina <jkosina@suse.cz>
* MIPS: Restore signalling NaN behaviour for abs.[sd]Chris Dearman2010-07-051-0/+1
| | | | | | | | | | | Atsushi Nemoto <anemo@mba.ocn.ne.jp> spotted that this had been incorrectly removed in a previous patch Signed-off-by: Chris Dearman <chris@mips.com> To: linux-mips@linux-mips.org Patchwork: http://patchwork.linux-mips.org/patch/1213/ Tested-by: Atsushi Nemoto <anemo@mba.ocn.ne.jp> Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
* MIPS: Fix abs.[sd] and neg.[sd] emulation for NaN operandsNigel Stephens2009-11-021-8/+3
| | | | | | | This patch ensures that the sign bit is always updated for NaN operands. Signed-off-by: Chris Dearman <chris@mips.com> Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
* [MIPS] ieee754[sd]p_neg workaroundAtsushi Nemoto2006-02-071-4/+10
| | | | | | | | | | It looks glibc's pow() assumes an unary '-' operation for any number (including NaNs) always inverts its sign bit (though IEEE754 does not specify the sign bit for NaNs). This patch make the kernel math-emu emulates real MIPS neg.[ds] instruction. Signed-off-by: Atsushi Nemoto <anemo@mba.ocn.ne.jp> Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
* Linux-2.6.12-rc2v2.6.12-rc2Linus Torvalds2005-04-161-0/+84
Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
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