/*
** GENERAL NOTE: This timer module has two functions to use it. First is a
** designed as a single-use interval timer. This is convenient for a frame
** rate display. It is accessed through the function TMXframe_rate(). The
** second mode of functionality is a stack of timers. In this mode, a time
** is kept for each timer on the stack, but only the timer at the top of the
** stack is accumulating time. A push operation stops the current timer and
** creates a new one, pushing it on the stack. Initially, there is a timer
** on the stack, but it is not accessible since there it was not pushed on
** the stack. A function could be added to gather this data, of course. A
** pop operation returns the time accumulated by the timer on the top of the
** stack and removes it. This implicitly restarts the timer that becomes
** the new top of the stack. A push operation stop the current timer (and
** adds in the time), and creates a new timer as the new top of the stack,
** starting it.
**
** The current time is read directly from /dev/mmem, to which an open file
** descriptor is maintained. The file is memory-mapped so that the address
** retrieved initially is always correct. Details on this procedure are in
** the manual page for syssgi(2) under SGI_QUERY_CYCLECTR. The units are
** obtained from the syssgi() call, in picoseconds per cycle. This value is
** then used to convert all returned times into seconds. Time values read
** read the clock are in cycles. This method of getting the current time is
** significantly faster than gettimeofday().
**
** ONE VERY IMPORTANT NOTE: In order not to take up a great deal of time,
** there is no policing of the order of calls. If you attempt to pop too
** many timers off the stack, the stack pointers will point into non-related
** data. Similarly, calling TMXframe_rate(), TMXpush(), or TMXpop() without
** calling TMXinit() will likely cause a segmentation violation or bus error,
** crashing your program.
*/
#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <fcntl.h>
#include <unistd.h>
#include <sys/mman.h>
#include <sys/syssgi.h>
#include <sys/immu.h>
#include <invent.h>
#include <bstring.h>
#include <quat.h>
#include <gl.h>
#include "time.h"
/* Mark's fix to Andrei's hack to make it compile under 6.2; */
#ifndef _PAGESZ
#define _PAGESZ ( getpagesize( ) )
#endif
/* These three variables are general information used for all timers */
static volatile unsigned long *iotimer_addr; /* hardware address of timer */
static int fd; /* file descriptor of mmem */
/* These variables are only for the general frame rate display */
static double sec_per_cyc; /* conversion factor for time */
static unsigned long last_frame_low = 0; /* time stamp last read */
/* These variables are for the stack of timers */
static unsigned long *acc_time; /* Total time attributed to this timer */
static unsigned long start_time; /* Time the current timer was started */
static unsigned long *cur_time; /* pointer to active timer */
/* This variable is for the time stamp function */
static unsigned long time_zero; /* Time the timer was initialized */
/*
** General initialization
** The argument is the number of timers that should be created on the stack.
*/
void
TMXinit( int n )
{
 unsigned long *time_a;
 unsigned int phys_addr, raddr, cycleval;
 inventory_t *iv;
 /* The following code is virtually copied from the syssgi(2) man page */
 /* Get the hardware address and cycle time (in picoseconds) */
 phys_addr = syssgi( SGI_QUERY_CYCLECNTR, &cycleval );
 if( phys_addr == ENODEV ) {
 fprintf( stderr, "TMXinit: Sorry, hardware counter not supported\n" );
 return;
 }
 /* Mask the address to be page-aligned */
 raddr = ( phys_addr & ~POFFMASK );
 /* Open the pseudo-kernel memory /dev/mmem */
 fd = open( "/dev/mmem", O_RDONLY );
 /* Map the page-aligned address */
 time_a = (unsigned long *) mmap( 0, POFFMASK, PROT_READ,
				 MAP_PRIVATE, fd, (int) raddr );
 /* Add back the offset to get the true address */
 time_a = (unsigned long *) ( (unsigned long) time_a + poff( phys_addr ) );
 /* Assign it to the variable visible throughout the module */
 iotimer_addr = (unsigned long *) time_a;
 /* Now, try to figure out what length of timer we have, and adjust the
 ** address accordingly - i.e. add one for a 64-bit timer to use only the
 ** low-order 32 bits. The constants for the inv_state field are in
 ** invent.h and get reported by "uname -m" (Unix command).
 */
 setinvent( );
 for( iv = getinvent( );
	 iv->inv_class != INV_PROCESSOR &#124;&#124; iv->inv_type != INV_CPUBOARD;
	 iv = getinvent( ) ) /*EMPTY*/;
 if( iv == NULL ) {
 printf( "TMXinit(): unable to determine CPU type, assuming 64-bit\n" );
 } else {
 switch( iv->inv_state ) {
 case INV_IP22BOARD: /* UNC: indigo[12], lysine, csg, lionfish, noyce */
	break; /* 32-bit timer */
 case INV_IP19BOARD: /* UNC: coons, histidine */
	iotimer_addr++; /* 64-bit timer, using only low-order 32 bits */
	break;
 case INV_IP21BOARD: /* UNC: milli - don't know what length */
 default:
	printf( "TMXinit(): unknown CPU type (%d), assuming 64-bit timer\n",
	 iv->inv_state );
 iotimer_addr++;
 break;
 } /* end switch */
 }
 endinvent( );
 /* Now the functionality that we desire */
 /* Timer stack initialization */
 acc_time = (unsigned long *) malloc( n * sizeof( unsigned long ) );
 if( acc_time == NULL ) {
 fprintf( stderr, "ERROR: Unable to initialize timer.\n" );
 fprintf( stderr, " The program should crash now.\n");
 }
 bzero( (void *) acc_time, n * sizeof( unsigned long ) );
 cur_time = acc_time;
 /* Frame rate timer initialization */
 /* Compute the number of cycles per second. This will be divided by the
 ** number of cycles to return Hertz.
 */
 sec_per_cyc = (double) cycleval / 1e+12;
 /* Prime the pump for the frame timer, timer stack, and the time stamp */
 time_zero = start_time = last_frame_low = *( iotimer_addr );
 return;
}
/* Clean up */
void
TMXdestroy( void )
{
 close( fd );
 if( acc_time != NULL ) {
 free( acc_time );
 acc_time = NULL;
 }
 return;
}
/*
** Stop the current timer.
** Create a new one.
** Push the new one on the stack and start it.
*/
void
TMXpush( void )
{
 unsigned long timestamp;
 /* Stop the previous timer and record the time */
 timestamp = *( iotimer_addr );
 *cur_time += timestamp - start_time;
 /* Initialize the new timer */
 cur_time++;
 *cur_time = 0;
 /* Start (time stamp) the new timer */
 start_time = timestamp;
 return;
}
double
TMXpop( void )
{
 unsigned long timestamp;
 double elapsed;
 /* Stop the timer and compute elapsed time in seconds */
 timestamp = *( iotimer_addr );
 *cur_time += timestamp - start_time;
 elapsed = *cur_time * sec_per_cyc;
 /* Point to the previous timer and restart it (new time stamp) */
 cur_time--;
 start_time = timestamp;
 return elapsed;
}
double
TMXframeRate( double *seconds )
{
 unsigned long low;
 double fr = 0.0;
 low = *( iotimer_addr );
 *seconds = (double) ( low - last_frame_low ) * sec_per_cyc;
 fr = 1.0 / *seconds;
 last_frame_low = low;
 return fr;
}
void
TMXsetMarker( void )
{
 time_zero = *( iotimer_addr );
 return;
}
double
TMXtimeStamp( void )
{
 double t;
 t = (double) ( *( iotimer_addr ) - time_zero ) * sec_per_cyc;
 return t;
}
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