/*
 *  Copyright (C) 2009 Seth Schultz
 *  Version 0.0.1
 *
 *  Libsource.c is a shared library aimed at reducing the system call overhead
 *  of the Source Dedicated Server, thus reducing server sides latencies.  
 *  Take this as my contribution to the community for always being helpful 
 *  in my journey for higher and more stable server side fps.  Please also 
 *  take note that this is my first release, and I am sure there are things 
 *  that can be done better.
 *
 *  This software 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 3 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, see <http://www.gnu.org/licenses/>.
 *
 *  ----------------------------------------------------------------------------
 *  If you are able and willing to help me further develop this library,
 *  please contact me on IRC.
 *
 *  Special thanks:
 *    Monk - Thank you for your brilliant blog, 
 *           it inspired all of my initial work.
 *    Baz - Thank you for your kernel config help
 *          and all the field testing you have done for me.
 *    Hrg - Thank you for your direction and your wiki.
 *    SRCDS Forums - Thank you all for the positive encouragement.
 *
 *  If I have forgotten anyone, I thank you and appreciate your previous 
 *  and continued support!
 *
 *  -DiSTANT
 * 
 *  Compile & Load
 *  ----------------
 *
 *  32-bit:
 *    gcc -shared -o libsource.so libsource.c -lrt
 *    LD_PRELOAD=./libsource.so ./srcds_run ...
 *
 *  64-bit:
 *    gcc -shared -m32 -o libsource.so libsource.c -lrt
 *    LD_PRELOAD_32=./libsource.so ./srcds_run ...
 *
 *  Need Help? Join us on IRC. 
 *    Server: irc.gamesurge.net
 *    Channel: #SourceKernel
 *
*/

#define _GNU_SOURCE
#include <dlfcn.h>
#include <signal.h>
#include <unistd.h>
#include <time.h>
#include <sys/select.h>
#include <sys/time.h>

#define CLOCK_ID CLOCK_REALTIME

int
gettimeofday(struct timeval *tp, struct timezone *tzp)
{
   struct timespec ts;

   //Try to get CLOCK_MONOTONIC working (however, might add time scew)
   clock_gettime(CLOCK_ID, &ts);
   tp->tv_sec = ts.tv_sec;
   tp->tv_usec = ts.tv_nsec / 1000;

   return (0);
}

int
low_latency_sleep(unsigned long msec)
{
   struct timespec req={0};
   time_t sec=(int)(msec/1000);

   msec = msec - (sec * 1000);

   req.tv_sec=sec;
   req.tv_nsec=msec*1000000L;

   while(nanosleep(&req,&req)==-1)
   continue;
   return 1;
}

extern int
usleep (__useconds_t __usec)
{
   low_latency_sleep(__usec/1000);
   return (0);
}

extern int
select (int nfds, fd_set *readfds, fd_set *writefds, fd_set *errorfds, struct timeval *timeout)
{
   //Instead of using pselect can we use poll? (pselect may be adding unecessary overhead)
   struct timespec ts;
   
   ts.tv_sec = timeout->tv_sec / 1000;
   ts.tv_nsec = timeout->tv_usec / 100000;
   
   return pselect(nfds, readfds, writefds, errorfds, &ts, NULL);
}