Joppe Blondel
838204653a
TODO: think of other way of shifting in data. Bit errors make uploading difficult
45 lines
1.1 KiB
C
45 lines
1.1 KiB
C
#include <stdint.h>
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#define GPIO_BASE 0x40000000u
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static volatile uint32_t * const R_FREQ = (volatile uint32_t *)(GPIO_BASE+0);
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static volatile uint32_t * const LEDS = (volatile uint32_t *)(GPIO_BASE+4);
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static volatile uint32_t * const LEDGR = (volatile uint32_t *)(GPIO_BASE+8);
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#define TIMER_BASE 0x40010000u
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static volatile uint32_t * const TIMER = (volatile uint32_t *)(TIMER_BASE+0);
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#define MSTATUS_MIE (1u << 3)
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#define MIE_MTIE (1u << 7)
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extern void trap_entry();
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static inline void irq_init() {
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/* mtvec first */
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asm volatile ("csrw mtvec, %0" :: "r"(trap_entry));
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/* enable machine timer interrupt */
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asm volatile ("csrs mie, %0" :: "r"(MIE_MTIE));
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/* global enable last */
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asm volatile ("csrs mstatus, %0" :: "r"(MSTATUS_MIE));
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}
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void timer_isr(){
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static int set = 0;
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*TIMER = 18400;
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*LEDGR = ~(*LEDGR);
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}
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void main(){
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irq_init();
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*LEDGR = 3;
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*TIMER = 18400;
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for(;;){
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for(int i=1000; i<10000; i++){
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*R_FREQ = i;
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for(int j=0; j<100; j++) asm volatile("nop");
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}
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}
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} |