glibc/manual/platform.texi
Tulio Magno Quites Machado Filho d9dc34cd56 Manual for platform-specific features and new __ppc_get_timebase inline.
[BZ #13743]
A new class of installed headers has been documented for low-level
platform-specific functionality.  PowerPC added the first instance with a
function to provide time base register access (__ppc_get_timebase).  This
is required for applications that measure time at high frequencies with
high precision that can't afford a syscall.
2012-06-04 13:46:37 -05:00

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@node Platform, Contributors, Maintenance, Top
@c %MENU% Describe all platform-specific facilities provided
@appendix Platform-specific facilities
@Theglibc{} can provide machine-specific functionality.
@menu
* PowerPC:: Facilities Specific to the PowerPC Architecture
@end menu
@node PowerPC
@appendixsec PowerPC-specific Facilities
Facilities specific to PowerPC that are not specific to a particular
operating system are declared in @file{sys/platform/ppc.h}.
@deftypefun {uint64_t} __ppc_get_timebase (void)
Read the current value of the Time Base Register.
The @dfn{Time Base Register} is a 64-bit register that stores a monotonically
incremented value updated at a system-dependent frequency that may be
different from the processor frequency. More information is available in
@cite{Power ISA 2.06b - Book II - Section 5.2}.
@code{__ppc_get_timebase} uses the processor's time base facility directly
without requiring assistance from the operating system, so it is very
efficient.
@end deftypefun