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// Copyright 2009 The Go Authors. All rights reserved.

// Use of this source code is governed by a BSD-style

// license that can be found in the LICENSE file.

#include "runtime.h"

#include <errno.h>

#include <string.h>

#include <time.h>

#include <sys/types.h>

#include <sys/stat.h>

#include <fcntl.h>

#include <unistd.h>

#include <syscall.h>

#include <linux/futex.h>

typedef struct timespec Timespec;

// Atomically,

//      if(*addr == val) sleep

// Might be woken up spuriously; that's allowed.

// Don't sleep longer than ns; ns < 0 means forever.

void

runtime_futexsleep(uint32 *addr, uint32 val, int64 ns)

{

        Timespec ts, *tsp;

        if(ns < 0)

                tsp = nil;

        else {

                ts.tv_sec = ns/1000000000LL;

                ts.tv_nsec = ns%1000000000LL;

                // Avoid overflow

                if(ts.tv_sec > 1<<30)

                        ts.tv_sec = 1<<30;

                tsp = &ts;

        }

        // Some Linux kernels have a bug where futex of

        // FUTEX_WAIT returns an internal error code

        // as an errno.  Libpthread ignores the return value

        // here, and so can we: as it says a few lines up,

        // spurious wakeups are allowed.

        syscall(__NR_futex, addr, FUTEX_WAIT, val, tsp, nil, 0);

}

// If any procs are sleeping on addr, wake up at most cnt.

void

runtime_futexwakeup(uint32 *addr, uint32 cnt)

{

        int64 ret;

        ret = syscall(__NR_futex, addr, FUTEX_WAKE, cnt, nil, nil, 0);

        if(ret >= 0)

                return;

        // I don't know that futex wakeup can return

        // EAGAIN or EINTR, but if it does, it would be

        // safe to loop and call futex again.

        runtime_printf("futexwakeup addr=%p returned %lld\n", addr, (long long)ret);

        *(int32*)0x1006 = 0x1006;

}

#ifndef O_CLOEXEC

#define O_CLOEXEC 0

#endif

static int32

getproccount(void)

{

        int32 fd, rd, cnt, cpustrlen;

        const char *cpustr;

        const byte *pos;

        byte *bufpos;

        byte buf[256];

        fd = open("/proc/stat", O_RDONLY|O_CLOEXEC, 0);

        if(fd == -1)

                return 1;

        cnt = 0;

        bufpos = buf;

        cpustr = "\ncpu";

        cpustrlen = strlen(cpustr);

        for(;;) {

                rd = read(fd, bufpos, sizeof(buf)-cpustrlen);

                if(rd == -1)

                        break;

                bufpos[rd] = 0;

                for(pos=buf; (pos=(const byte*)strstr((const char*)pos, cpustr)) != nil; cnt++, pos++) {

                }

                if(rd < cpustrlen)

                        break;

                memmove(buf, bufpos+rd-cpustrlen+1, cpustrlen-1);

                bufpos = buf+cpustrlen-1;

        }

        close(fd);

        return cnt ? cnt : 1;

}

void

runtime_osinit(void)

{

        runtime_ncpu = getproccount();

}

void

runtime_goenvs(void)

{

        runtime_goenvs_unix();

}