118 lines
2.6 KiB
C
118 lines
2.6 KiB
C
#include <stdint.h>
|
|
#include <stddef.h>
|
|
#include <stdbool.h>
|
|
#include <lib/blib.h>
|
|
#include <lib/print.h>
|
|
#include <lib/rand.h>
|
|
#include <sys/cpu.h>
|
|
#include <mm/pmm.h>
|
|
|
|
// TODO: Find where this mersenne twister implementation is inspired from
|
|
// and properly credit the original author(s).
|
|
|
|
#define rdrand(type) ({ \
|
|
type ret; \
|
|
asm volatile ( \
|
|
"1: " \
|
|
"rdrand %0;" \
|
|
"jnc 1b;" \
|
|
: "=r" (ret) \
|
|
); \
|
|
ret; \
|
|
})
|
|
|
|
#define rdseed(type) ({ \
|
|
type ret; \
|
|
asm volatile ( \
|
|
"1: " \
|
|
"rdrand %0;" \
|
|
"jnc 1b;" \
|
|
: "=r" (ret) \
|
|
); \
|
|
ret; \
|
|
})
|
|
|
|
#define rdtsc(type) ({ \
|
|
type ret; \
|
|
asm volatile ( \
|
|
"rdtsc;" \
|
|
: "=A" (ret) \
|
|
); \
|
|
ret; \
|
|
})
|
|
|
|
static bool rand_initialised = false;
|
|
|
|
#define n ((int)624)
|
|
#define m ((int)397)
|
|
#define matrix_a ((uint32_t)0x9908b0df)
|
|
#define msb ((uint32_t)0x80000000)
|
|
#define lsbs ((uint32_t)0x7fffffff)
|
|
|
|
static uint32_t *status;
|
|
static int ctr;
|
|
|
|
static void init_rand(void) {
|
|
uint32_t seed = ((uint32_t)0xc597060c * rdtsc(uint32_t))
|
|
* ((uint32_t)0xce86d624)
|
|
^ ((uint32_t)0xee0da130 * rdtsc(uint32_t));
|
|
|
|
uint32_t eax, ebx, ecx, edx;
|
|
|
|
// Check for rdseed
|
|
if (cpuid(0x07, 0, &eax, &ebx, &ecx, &edx) && (ebx & (1 << 18))) {
|
|
seed *= (seed ^ rdseed(uint32_t));
|
|
} else if (cpuid(0x01, 0, &eax, &ebx, &ecx, &edx) && (ecx & (1 << 30))) {
|
|
seed *= (seed ^ rdrand(uint32_t));
|
|
}
|
|
|
|
status = ext_mem_alloc(n);
|
|
|
|
srand(seed);
|
|
|
|
rand_initialised = true;
|
|
}
|
|
|
|
void srand(uint32_t s) {
|
|
status[0] = s;
|
|
for (ctr = 1; ctr < n; ctr++)
|
|
status[ctr] = (1812433253 * (status[ctr - 1] ^ (status[ctr - 1] >> 30)) + ctr);
|
|
}
|
|
|
|
uint32_t rand32(void) {
|
|
if (!rand_initialised)
|
|
init_rand();
|
|
|
|
const uint32_t mag01[2] = {0, matrix_a};
|
|
|
|
if (ctr >= n) {
|
|
for (int kk = 0; kk < n - m; kk++) {
|
|
uint32_t y = (status[kk] & msb) | (status[kk + 1] & lsbs);
|
|
status[kk] = status[kk + m] ^ (y >> 1) ^ mag01[y & 1];
|
|
}
|
|
|
|
for (int kk = n - m; kk < n - 1; kk++) {
|
|
uint32_t y = (status[kk] & msb) | (status[kk + 1] & lsbs);
|
|
status[kk] = status[kk + (m - n)] ^ (y >> 1) ^ mag01[y & 1];
|
|
}
|
|
|
|
uint32_t y = (status[n - 1] & msb) | (status[0] & lsbs);
|
|
status[n - 1] = status[m - 1] ^ (y >> 1) ^ mag01[y & 1];
|
|
|
|
ctr = 0;
|
|
}
|
|
|
|
uint32_t res = status[ctr++];
|
|
|
|
res ^= (res >> 11);
|
|
res ^= (res << 7) & 0x9d2c5680;
|
|
res ^= (res << 15) & 0xefc60000;
|
|
res ^= (res >> 18);
|
|
|
|
return res;
|
|
}
|
|
|
|
uint64_t rand64(void) {
|
|
return (((uint64_t)rand32()) << 32) | (uint64_t)rand32();
|
|
}
|