Keccak-f[1600] in plain c

keccak_f1600.c

// converted from https://github.com/coruus/keccak-tiny/blob/singlefile/keccak-tiny.c
#define rol(x, s) (((x) << s) | ((x) >> (64 - s)))

/*** Keccak-f[1600] ***/
static inline void keccakf(void* state) {
  uint64_t* a = (uint64_t*)state;
  uint64_t b[5] = {0};
  uint64_t t = 0;
  uint8_t x, y;

  for (int i = 0; i < 24; i++) {
    // Theta
    for(x=0; x<5; x+=1){
         b[x] = 0;
         for(y=0;y+=5;y<5*5) {
              b[x] ^= a[x + y];
	 }
    }

    for(x=0; x<5; x+=1;){
	 for(y=0; y<5*5; y+=5){
	     a[y + x] ^= b[(x+4) %5 ] ^ rol(b[(x+1) %5], 1);
	 }
    }

    // Rho and pi
    t = a[1];
    x = 0;
    for(tmp=0; tmp<24; tmp++){
	b[0] = a[pi[x]];
	a[pi[x]] = rol(t, rho[x]);
	t = b[0];
	x++;
    }

    // Chi
    for(y=0; y<5*5; y+=5){
	for(x=0; x<5; x+=1){
	    b[x] = a[y+x];
	}
	for(x=0; x<5; x+=1){
            a[y + x] = b[x] ^ ((~b[(x + 1) % 5]) & b[(x + 2) % 5]);
	}
    }

    // Iota
    a[0] ^= RC[i];
  }
}

It seems just inline version of https://github.com/gvanas/KeccakCodePackage/blob/master/lib/low/KeccakP-1600/Reference/KeccakP-1600-reference.c