From d9dc34cd569bcfe714fe8c708e58c028106e8b2e Mon Sep 17 00:00:00 2001 From: Tulio Magno Quites Machado Filho Date: Mon, 4 Jun 2012 13:46:37 -0500 Subject: 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. --- sysdeps/powerpc/sys/platform/ppc.h | 47 ++++++++++++++++++++++++++++++++++++++ 1 file changed, 47 insertions(+) create mode 100644 sysdeps/powerpc/sys/platform/ppc.h (limited to 'sysdeps/powerpc/sys') diff --git a/sysdeps/powerpc/sys/platform/ppc.h b/sysdeps/powerpc/sys/platform/ppc.h new file mode 100644 index 0000000000..165652c7cc --- /dev/null +++ b/sysdeps/powerpc/sys/platform/ppc.h @@ -0,0 +1,47 @@ +/* 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 + . */ + +#ifndef _SYS_PLATFORM_PPC_H +#define _SYS_PLATFORM_PPC_H 1 + +#include + +/* 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 */ -- cgit v1.2.1