rand.c

#include <emscripten.h>
#include <stdio.h>
#include <stdlib.h>

static uint64_t x;

EMSCRIPTEN_KEEPALIVE uint64_t xorShiftSeed(int initialState) {
  x = initialState;// & 0xFFFFFFFFFFFFFFFFL;
  return x;
}

EMSCRIPTEN_KEEPALIVE uint64_t xorShift1() {
  x ^= (x << 13);
  x ^= x >> 7;
  x ^= (x << 17);
  return x;
}

EMSCRIPTEN_KEEPALIVE uint64_t* xorShift2(int n) {
  uint64_t* a = (uint64_t*)malloc(sizeof(uint64_t) * n);
  for (int i = 0; i < n; i++) {
    a[i] = xorShift1();
  }
  return a;
}

int main() {
  EM_ASM(
	 
    _xorShiftSeed(1);
    
    const a1 = [];
    console.time("xorShift1");
    for (let i = 0; i < 10000000; i += 1) {
	a1.push(_xorShift1());
    }
    console.timeEnd("xorShift1");

    _xorShiftSeed(1);
    console.time("xorShift2");
    var a2 = _xorShift2(10000000);
    console.timeEnd("xorShift2");
    console.log(typeof(a2));
    console.log(a2);
    for (let i = 0; i < 10; i++) {
      console.log(`${Module.getValue(a2+i*4, 'i32')}`);
    }
  );
}

$ emcc rand.c -o rand.js -sEXPORTED_FUNCTIONS=["_xorShiftSeed","_xorShift1","_xorShift2","getValue","_main"] -sINITIAL_MEMORY=100mb -O2 -sWASM_BIGINT

xorShift1: 821.662ms
xorShift2: 25.896ms
number
5244824
1082269761
0
201397313
268452102
1854285353
-1692498897
1432191013
-178981629
-1873178011
-2046025808