cycles.h

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/*
 * Copyright (C) 2005-2006 Taybin Rutkin <taybin@taybin.com>
 * Copyright (C) 2007-2008 Paul Davis <paul@linuxaudiosystems.com>
 * Copyright (C) 2008-2011 David Robillard <d@drobilla.net>
 * Copyright (C) 2012 Carl Hetherington <carl@carlh.net>
 * Copyright (C) 2018-2019 Robin Gareus <robin@gareus.org>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program 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 General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program; if not, write to the Free Software Foundation, Inc.,
 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 */
 
#pragma once
 
#include <stdint.h>
 
#if defined(__i386__) || defined(__x86_64__)
 
/*
 * Standard way to access the cycle counter on i586+ CPUs.
 * Currently only used on SMP.
 *
 * If you really have a SMP machine with i486 chips or older,
 * compile for that, and this will just always return zero.
 * That's ok, it just means that the nicer scheduling heuristics
 * won't work for you.
 *
 * We only use the low 32 bits, and we'd simply better make sure
 * that we reschedule before that wraps. Scheduling at least every
 * four billion cycles just basically sounds like a good idea,
 * regardless of how fast the machine is.
 */
typedef uint64_t cycles_t;
 
#if defined(__x86_64__)
 
#define rdtscll(lo, hi) \
        __asm__ __volatile__("rdtsc" : "=a" (lo), "=d" (hi))
 
static inline cycles_t get_cycles (void)
{
        cycles_t lo, hi;
 
        rdtscll(lo, hi);
        return lo;
}
 
#else
 
#define rdtscll(val) \
__asm__ __volatile__("rdtsc" : "=A" (val))
 
static inline cycles_t get_cycles (void)
{
        cycles_t ret;
 
        rdtscll(ret);
        return ret & 0xffffffff;
}
#endif
 
#elif defined(__powerpc64__)
 
#ifdef __linux__
#include <sys/platform/ppc.h>
typedef uint64_t cycles_t;
static inline cycles_t get_cycles(void)
{
        return __ppc_get_timebase();
}
#elif defined(__FreeBSD__)
typedef uint64_t cycles_t;
static inline cycles_t get_cycles(void)
{
       cycles_t tbr;
       asm volatile("mfspr %0, 268" : "=r"(tbr));
       return tbr;
}
#endif
        
#elif defined(__powerpc__)
 
#define CPU_FTR_601 0x00000100
 
typedef uint32_t cycles_t;
 
/*
 * For the "cycle" counter we use the timebase lower half.
 * Currently only used on SMP.
 */
 
static inline cycles_t get_cycles(void)
{
        cycles_t ret = 0;
 
        __asm__ __volatile__(
                "98: mftb %0\n"
                "99:\n"
                ".section __ftr_fixup,\"a\"\n"
                " .long %1\n"
                " .long 0\n"
                " .long 98b\n"
                " .long 99b\n"
                ".previous"
                : "=r" (ret) : "i" (CPU_FTR_601));
        return ret;
}
 
#elif defined(__ia64__)
/* ia64 */
 
typedef uint32_t cycles_t;
static inline cycles_t
get_cycles (void)
{
        cycles_t ret;
        __asm__ __volatile__ ("mov %0=ar.itc" : "=r"(ret));
        return ret;
}
 
#elif defined(__alpha__)
/* alpha */
 
/*
 * Standard way to access the cycle counter.
 * Currently only used on SMP for scheduling.
 *
 * Only the low 32 bits are available as a continuously counting entity.
 * But this only means we'll force a reschedule every 8 seconds or so,
 * which isn't an evil thing.
 */
 
typedef uint32_t cycles_t;
static inline cycles_t get_cycles (void)
{
        cycles_t ret;
        __asm__ __volatile__ ("rpcc %0" : "=r"(ret));
        return ret;
}
 
#elif defined(__s390__)
/* s390 */
 
typedef uint32_t long cycles_t;
static inline cycles_t get_cycles(void)
{
        cycles_t cycles;
        __asm__("stck 0(%0)" : : "a" (&(cycles)) : "memory", "cc");
        return cycles >> 2;
}
 
#elif defined(__hppa__)
/* hppa/parisc */
 
#define mfctl(reg)      ({              \
        uint32_t cr;               \
        __asm__ __volatile__(           \
                "mfctl " #reg ",%0" :   \
                 "=r" (cr)              \
        );                              \
        cr;                             \
})
 
typedef uint32_t cycles_t;
static inline cycles_t get_cycles (void)
{
        return mfctl(16);
}
 
#elif defined(__mips__)
/* mips/mipsel */
 
/*
 * Standard way to access the cycle counter.
 * Currently only used on SMP for scheduling.
 *
 * Only the low 32 bits are available as a continuously counting entity.
 * But this only means we'll force a reschedule every 8 seconds or so,
 * which isn't an evil thing.
 *
 * We know that all SMP capable CPUs have cycle counters.
 */
 
#define __read_32bit_c0_register(source, sel)               \
({ int __res;                                               \
        if (sel == 0)                                           \
                __asm__ __volatile__(                               \
                        "mfc0\t%0, " #source "\n\t"                     \
                        : "=r" (__res));                                \
        else                                                    \
                __asm__ __volatile__(                               \
                        ".set\tmips32\n\t"                              \
                        "mfc0\t%0, " #source ", " #sel "\n\t"           \
                        ".set\tmips0\n\t"                               \
                        : "=r" (__res));                                \
        __res;                                                  \
})
 
/* #define CP0_COUNT $9 */
#define read_c0_count()         __read_32bit_c0_register($9, 0)
 
typedef uint32_t cycles_t;
static inline cycles_t get_cycles (void)
{
        return read_c0_count();
}
 
/* begin mach */
#elif defined(__APPLE__)
 
#include <CoreAudio/HostTime.h>
 
typedef UInt64 cycles_t;
static inline cycles_t get_cycles (void)
{
        UInt64 time = AudioGetCurrentHostTime();
        return AudioConvertHostTimeToNanos(time);
}
/* end mach  */
 
#else
 
/* debian: sparc, arm, m68k */
 
#ifndef COMPILER_MSVC
/* GRRR... Annoyingly, #warning aborts the compilation for MSVC !!  */
#warning You are compiling libardour on a platform for which ardour/cycles.h needs work
#endif
 
#include <sys/time.h>
 
typedef long cycles_t;
 
static inline cycles_t get_cycles(void)
{
        struct timeval tv;
        gettimeofday (&tv, NULL);
 
        return tv.tv_usec;
}
 
#endif