C Random Number Generation (pure C code, no libraries or functions)

Question

I need to generate some random numbers in C for testing and debugging the system. The system is a custom hardware (SoC) with a limited set of functions so I can only use basic m

Answer 1

You can try Multiply-with-carry by George Marsaglia.

Code from Wikipedia:

#include 

#define PHI 0x9e3779b9

static uint32_t Q[4096], c = 362436;

void init_rand(uint32_t x)
{
    int i;

    Q[0] = x;
    Q[1] = x + PHI;
    Q[2] = x + PHI + PHI;

    for (i = 3; i < 4096; i++)
            Q[i] = Q[i - 3] ^ Q[i - 2] ^ PHI ^ i;
}

uint32_t rand_cmwc(void)
{
    uint64_t t, a = 18782LL;
    static uint32_t i = 4095;
    uint32_t x, r = 0xfffffffe;
    i = (i + 1) & 4095;
    t = a * Q[i] + c;
    c = (t >> 32);
    x = t + c;
    if (x < c) {
            x++;
            c++;
    }
    return (Q[i] = r - x);
}