rpi4-osdev/part12-wgt/examples/wgt03.c

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#include "wgt.h"
#include "include/mb.h"
// ######## REQUIRED FUNCTIONS ########
unsigned long state0 = 1000;
unsigned long state1 = 2000;
unsigned long rand(void)
{
unsigned long s1 = state0;
unsigned long s0 = state1;
state0 = s0;
s1 ^= s1 << 23;
s1 ^= s1 >> 17;
s1 ^= s0;
s1 ^= s0 >> 26;
state1 = s1;
return state0 + state1;
}
void wait_msec(unsigned int n)
{
register unsigned long f, t, r;
// Get the current counter frequency
asm volatile ("mrs %0, cntfrq_el0" : "=r"(f));
// Read the current counter
asm volatile ("mrs %0, cntpct_el0" : "=r"(t));
// Calculate expire value for counter
t+=((f/1000)*n)/1000;
do{asm volatile ("mrs %0, cntpct_el0" : "=r"(r));}while(r<t);
}
// ######## STUB FUNCTIONS ########
unsigned int kb = 0;
unsigned int kbhit(void) {
kb++;
return kb / 15000;
}
void getch(void) {
wait_msec(0x500000);
kb = 0;
}
// ######## WGT EXAMPLES ########
#define TIMERSPEED 60 /* timer_routine is called 60 times per second */
int timer; /* Counts how many times it has been called */
int clearcount; /* Counts the number of screen clears. */
extern int get_el(void);
void timer_routine (void)
{
timer++;
}
void wgt03()
{
vga256 (); /* Initialize WGT system */
debugstr ("WGT Example #3"); debugcrlf(); debugcrlf();
debugstr ("This program will use the wcls routine"); debugcrlf();
debugstr ("to clear the screen using random"); debugcrlf();
debugstr ("colors as fast as it can until you"); debugcrlf();
debugstr ("press a key."); debugcrlf(); debugcrlf();
debugstr ("It will then report the highest frame"); debugcrlf();
debugstr ("rate possible on your computer."); debugcrlf(); debugcrlf(); debugcrlf();
int el = get_el();
debugstr("Exception level: "); debughex(el); debugcrlf();
int setter = set_clock_rate(get_max_clock());
debugstr("Set clock returned "); debughex(setter); debugcrlf(); debugcrlf(); debugcrlf();
debugstr ("Press any key to continue.");
getch ();
clearcount = 0;
timer = 0;
winittimer ();
wstarttimer (timer_routine, TIMERSPEED);
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debugreset();
while (!kbhit ())
{
wcls(vgapal[rand() % 256]); /* Clear with random color out of 256 */
clearcount++;
}
wstoptimer ();
wdonetimer ();
getch ();
wcls(vgapal[0]);
int clock = get_clock_rate();
debugstr("Clock rate: "); debughex(clock); debugcrlf();
int maxclock = get_max_clock();
debugstr("Max clock rate: "); debughex(maxclock); debugcrlf();
unsigned int fps = clearcount / (timer / TIMERSPEED);
debughex(fps); debugstr("frames per second"); debugcrlf(); debugcrlf(); debugcrlf();
debugstr ("This is the highest frame rate your"); debugcrlf();
debugstr ("computer can produce for full screen"); debugcrlf();
debugstr ("animation.");
}
void main()
{
wgt03();
while (1);
}