glibc/ports/sysdeps/mips/fpu
Maciej W. Rozycki b72ca61b71 MIPS: Correct the handling of reserved FCSR bits
Reserved bits in the Floating-Point Control and Status Register (FCSR)
should not be implicitly cleared by fedisableexcept or feenableexcept,
there is no reason to.  Among these are the 8 condition codes and one of
the two bits reserved for architecture implementers (bits #22 & #21).

As to the latter, there is no reason to treat any of them as reserved
either, they should be user controllable and settable via __fpu_control
override as the user sees fit.  For example in processors implemented by
MIPS Technologies, such as the 5Kf or the 24Kf, these bits are used to
change the treatment of denormalised operands and tiny results: bit #22
is Flush Override (FO) and bit #21 is Flush to Nearest (FN).  They cause
non-IEEE-compliant behaviour, but some programs may have a use for such
modes of operation; the library should not obstruct such use just as it
does not for the architectural Flush to Zero (FS) bit (bit #24).

Therefore the change adjusts the reserved mask accordingly and also
documents the distinction between bits 22:21 and 20:18.
2013-08-22 17:55:17 +01:00
..
e_sqrt.c Add support for building as MIPS16 code. 2013-02-27 23:45:07 +00:00
e_sqrtf.c Add support for building as MIPS16 code. 2013-02-27 23:45:07 +00:00
fclrexcpt.c Update copyright notices with scripts/update-copyrights. 2013-01-02 19:05:09 +00:00
fedisblxcpt.c MIPS: Correct the handling of reserved FCSR bits 2013-08-22 17:55:17 +01:00
feenablxcpt.c MIPS: Correct the handling of reserved FCSR bits 2013-08-22 17:55:17 +01:00
fegetenv.c Update copyright notices with scripts/update-copyrights. 2013-01-02 19:05:09 +00:00
fegetexcept.c Update copyright notices with scripts/update-copyrights. 2013-01-02 19:05:09 +00:00
fegetround.c Update copyright notices with scripts/update-copyrights. 2013-01-02 19:05:09 +00:00
feholdexcpt.c Update copyright notices with scripts/update-copyrights. 2013-01-02 19:05:09 +00:00
fenv_libc.h Update copyright notices with scripts/update-copyrights. 2013-01-02 19:05:09 +00:00
fesetenv.c Update copyright notices with scripts/update-copyrights. 2013-01-02 19:05:09 +00:00
fesetround.c Update copyright notices with scripts/update-copyrights. 2013-01-02 19:05:09 +00:00
feupdateenv.c Update copyright notices with scripts/update-copyrights. 2013-01-02 19:05:09 +00:00
fgetexcptflg.c Remove trailing whitespace in ports. 2013-06-05 20:26:40 +00:00
fraiseexcpt.c Remove trailing whitespace in ports. 2013-06-05 20:26:40 +00:00
fsetexcptflg.c Update copyright notices with scripts/update-copyrights. 2013-01-02 19:05:09 +00:00
ftestexcept.c Update copyright notices with scripts/update-copyrights. 2013-01-02 19:05:09 +00:00