62 lines
1.3 KiB
C
62 lines
1.3 KiB
C
#include "printf.h"
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typedef unsigned long long uint64_t;
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typedef unsigned long uint32_t;
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#define MTIME_BASE 0x0200BFF8
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volatile uint32_t* mtime_upper = (uint32_t*)(MTIME_BASE+4);
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volatile uint32_t* mtime_lower = (uint32_t*)MTIME_BASE;
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#define FRAMEBUFFER_BASE 0x1D385000
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uint64_t read_mtime_atomic() {
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uint32_t upper1, lower, upper2;
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do {
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upper1 = *mtime_upper;
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lower = *mtime_lower;
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upper2 = *mtime_upper;
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} while (upper1 != upper2); // Repeat if upper changed during the process
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return ((uint64_t)upper1 << 32) | lower;
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}
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uint32_t timediff_ms(uint64_t start, uint64_t end) {
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uint64_t total = end-start;
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// Clock rate is currently 1MHz
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return (uint32_t)total / 1000;
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}
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int fib(int n) {
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if (n == 0 || n == 1)
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return 1;
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return fib(n-1) + fib(n-2);
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}
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void draw() {
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for (int i = 0; i< 640; i++) {
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for (int j = 0; j < 480; j++) {
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uint32_t color = i*j;
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uint32_t* addr = (uint32_t*)(FRAMEBUFFER_BASE + ((j*640) + i) *4);
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*addr = color;
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}
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}
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}
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int main() {
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uint64_t start = read_mtime_atomic();
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draw();
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uint64_t end = read_mtime_atomic();
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int n = 24;
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int res = fib(n);
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uint32_t total_msec = timediff_ms(start, end);
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printf("fib(%d) = %d\n", n, res);
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printf("time: %dms\n", total_msec);
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return 0;
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}
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