// vim:fileencoding=utf-8:foldmethod=marker

#include "xorshift.h"
#include "../splitmix64/splitmix64.h"
#include "../../common/aliases/aliases.h"
#include "../../common/misc/misc_utils.h"
#include <stdlib.h>
#include <time.h>

WpXor256State wpPrngXorshiftInit(void) {
	return wpPrngXorshiftInitWithSeed(0);
}

WpXor256State wpPrngXorshiftInitWithSeed(u64 seed) {
	WpSplitmix64State sm64;
	if (seed > 0) {
		sm64 = wpPrngSplitmix64InitWithSeed(seed);
	} else {
		sm64 = wpPrngSplitmix64Init();
	}

	return (WpXor256State){
		.x = wpPrngSplitmix64(&sm64),
		.y = wpPrngSplitmix64(&sm64),
		.z = wpPrngSplitmix64(&sm64),
		.w = wpPrngSplitmix64(&sm64),
	};
}

u64 wpPrngXorshift256(WpXor256State *state) {
	u64 t = state->x ^ (state->x << 11);

	state->x = state->y;
	state->y = state->z;
	state->z = state->w;
	state->w = (state->w ^ (state->w >> 19)) ^ (t ^ (t >> 8));

	return state->w;
}

u64 wpPrngXorshift256ss(WpXor256State *state) {
	const u64 result = wpMiscUtilsRotl64(state->z * 5, 7) * 9;
	const u64 t = state->z << 17;

	state->y ^= state->w;
	state->x ^= state->z;
	state->z ^= state->y;
	state->w ^= state->x;

	state->y ^= t;
	state->x = wpMiscUtilsRotl64(state->x, 45);

	return result;
}

u64 wpPrngXorshift256p(WpXor256State *state) {
	const u64 result = state->w + state->x;
	const u64 t = state->z << 17;

	state->y ^= state->w;
	state->x ^= state->z;
	state->z ^= state->y;
	state->w ^= state->x;

	state->y ^= t;
	state->x  = wpMiscUtilsRotl64(state->x, 45);

	return result;
}

u64 wpPrngXorshift256InRange(WpXor256State *state, u64 start, u64 end) {
	return wpPrngXorshift256(state) % (end - start) + start;
}

u64 wpPrngXorshift256ssInRange(WpXor256State *state, u64 start, u64 end) {
	return wpPrngXorshift256ss(state) % (end - start) + start;
}

u64 wpPrngXorshift256pInRange(WpXor256State *state, u64 start, u64 end) {
	return wpPrngXorshift256p(state) % (end - start) + start;
}

u64 wpPrngXorshift256Choice(WpXor256State *state, u64 available_choices) {
	return wpPrngXorshift256(state) % available_choices;
}

u64 wpPrngXorshift256ssChoice(WpXor256State *state, u64 available_choices) {
	return wpPrngXorshift256ss(state) % available_choices;
}

u64 wpPrngXorshift256pChoice(WpXor256State *state, u64 available_choices) {
	return wpPrngXorshift256p(state) % available_choices;
}