risc-v-tlm/tests/C/timer/timer.c

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#include <stdio.h>
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#define TIMER (*(uint64_t volatile *)0x40004000)
#define TIMER_CMP (*(uint64_t volatile *)0x40004008)
#define TRACE (*(unsigned char volatile *)0x40000000)
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volatile uint32_t ticks = 0;
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int _write(int file, const char *ptr, int len) {
int x;
for (x = 0; x < len; x++) {
TRACE = *ptr++;
}
return (len);
}
void timer_ISR() {
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volatile uint32_t timer_value;
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ticks++;
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timer_value = TIMER;
// timer is in nanoseconds, set to 1 ms.
// comparator value fixed to take into account number of instructions executed
TIMER_CMP = timer_value + 610;
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}
void register_timer_isr() {
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asm volatile("la t0, TIMER_CMP_INT");
asm volatile("csrw mtvec, t0");
asm volatile("li t1, 0x888");
asm volatile("csrw mie, t1");
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// enable interrupts
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asm volatile( "csrs mstatus,0x0F" );
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}
int main(void) {
uint32_t timer_value;
uint32_t start_time;
register_timer_isr();
start_time = TIMER;
TIMER_CMP = start_time + 10000;
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printf("set timer to %d ns\n", start_time + 10000);
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do {
timer_value = TIMER;
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} while (timer_value < start_time + 2000000);
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printf("Timer: %d ns\n", timer_value);
printf("ticks: %d\n", ticks);
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if (ticks > 2100) {
printf("Test OK!\n");
}
printf("Finish\n");
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asm volatile ("ecall");
return 0;
}