rand.c

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#include "hal/rand/rand.h"
#include "hal/acpi/hpet.h"
#include "hal/cpu/cpuid.h"
#include "init/init.h"
#include "libk/serial.h"
 
static boolean_t random_available = 0;
 
#define RAND_MAX 0xFFFFFFFF
 
INIT(Rand) {
    uint32_t ecx, unused;
    cpuid(1, 0, &unused, &unused, &ecx, &unused);
    random_available = (ecx >> 30) & 1;
    LOG_INFO("Rand ", "random is available %d", random_available);
}
 
uint32_t vxRand() {
    if (random_available) {
        uint32_t rand = 0;
        asm volatile("rdrand %0" : "=r"(rand));
        return rand & RAND_MAX;
    } else if (vxHPETIsAvailable()) {
        // fallback using HPET if available
        uint32_t rand = vxHPETGetMainCount() & RAND_MAX;
        return rand;
    }
    return 0;
}