31 lines
748 B
C
31 lines
748 B
C
#include <stall.h>
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#include <stdint.h>
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static uint64_t stall_read_tsc (void) {
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uint32_t lo, hi;
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__asm__ volatile ("rdtsc" : "=a"(lo), "=d"(hi));
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return ((uint64_t)hi << 32) | lo;
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}
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static uint64_t stall_get_tsc_freq_hz (void) {
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uint32_t eax, ebx, ecx, edx;
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__asm__ volatile ("cpuid" : "=a"(eax), "=b"(ebx), "=c"(ecx), "=d"(edx) : "a"(0x15));
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if (eax == 0 || ebx == 0 || ecx == 0)
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return 2500000000ULL;
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return (uint64_t)ecx * ebx / eax;
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}
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void stall_ms (uint64_t ms) {
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uint64_t freq_hz = stall_get_tsc_freq_hz ();
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uint64_t cycles = freq_hz / 1000;
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uint64_t wait_cycles = ms * cycles;
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uint64_t now = stall_read_tsc ();
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while ((stall_read_tsc () - now) < wait_cycles)
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__asm__ volatile ("pause" ::: "memory");
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}
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