glibc/sysdeps/powerpc/sys/platform/ppc.h
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

48 lines
1.5 KiB
C

/* Facilities specific to the PowerPC architecture
Copyright (C) 2012 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<http://www.gnu.org/licenses/>. */
#ifndef _SYS_PLATFORM_PPC_H
#define _SYS_PLATFORM_PPC_H 1
#include <stdint.h>
/* Read the Time Base Register. */
static inline uint64_t
__ppc_get_timebase (void)
{
#ifdef __powerpc64__
uint64_t __tb;
/* "volatile" is necessary here, because the user expects this assembly
isn't moved after an optimization. */
__asm__ volatile ("mfspr %0, 268" : "=r" (__tb));
return __tb;
#else /* not __powerpc64__ */
uint32_t __tbu, __tbl, __tmp; \
__asm__ volatile ("0:\n\t"
"mftbu %0\n\t"
"mftbl %1\n\t"
"mftbu %2\n\t"
"cmpw %0, %2\n\t"
"bne- 0b"
: "=r" (__tbu), "=r" (__tbl), "=r" (__tmp));
return (((uint64_t) __tbu << 32) | __tbl);
#endif /* not __powerpc64__ */
}
#endif /* sys/platform/ppc.h */