/**
 * Compile with
 *
 * $ gcc -Wall -I../include -L.. -o div2 div2.c -lsole
 */
#include <sole.h>
#include <stdio.h>
#include <stdlib.h>
#include "../src/blk256.h"

#define B32	(double)(1ULL << 32)
#define B64	((double)B32*B32)
#define B128	((double)B64*B64)
#define B192	((double)B128*B64)
#define B256	((double)B128*B128)

#define LOWMASK ((1ULL << 32) - 1)
#define lo(x) ((x) & LOWMASK)
#define hi(x) ((x) >> 32)

#define u64(x) ((uint64_t)(x))

#define blk256_print(name, t) printf("%s: {%d, [%lu, %lu, %lu, %lu]}\n", name, (t).mx, (t).x[3], (t).x[2], (t).x[1], (t).x[0])


#define blk256_set(t, max, x3, x2, x1, x0)	\
	do {					\
		char tmx = max;			\
		uint64_t tx3 = x3;		\
		uint64_t tx2 = x2;		\
		uint64_t tx1 = x1;		\
		uint64_t tx0 = x0;		\
		(t)->mx   = tmx; 		\
		(t)->x[3] = tx3;		\
		(t)->x[2] = tx2;		\
		(t)->x[1] = tx1;		\
		(t)->x[0] = tx0;		\
	} while(0)

/**
 * Provide a double representation of a 256-bit block
 */
double blk256_as_double(blk256_t *x)
{

	return (double)(x->mx) * B256
		+ (double)(x->x[3]) * B192
		+ (double)(x->x[2]) * B128
		+ (double)(x->x[2]) * B64
		+ (double)(x->x[0]);
}

double blk128_as_double(blk128_t *y)
{
	return (double)y->hi * B64 + (double)y->lo;
}

void double_as_blk256(blk256_t *rop, double x)
{
	rop->mx = (char)(x / B256);
	rop->x[3] = (uint64_t)(x / B192);
	rop->x[2] = (uint64_t)(x / B128);
	rop->x[1] = (uint64_t)(x / B64);
	rop->x[0] = (uint64_t)x;
}


int main()
{
	blk256_t x, z, q;
	blk128_t y = {UINT64_MAX, UINT64_MAX - 2};
	blk256_set(&x, 1, 0, 0, 0, 0);

	/* First division */
	double xx = blk256_as_double(&x);
	double yy = blk128_as_double(&y);

	double zz = xx / yy;

	blk256_print("x", x);
	printf("x=%lg\n", xx);

	double_as_blk256(&z, zz);
	blk256_print("z", z);

	blk256_t rop;
	blk256_mul_blk128(&rop, &z, &y);
	blk256_print("z*y", rop);

	blk256_sub(&x, &x, &rop);
	blk256_print("x", x);

	blk256_cp(&q, &z); /* Save q */

	/* Next division */
	printf("=== Next division\n");
	xx = blk256_as_double(&x);
	zz = xx / yy;

	double_as_blk256(&z, zz);
	printf("zz=%lg\n", zz);
	blk256_print("z", z);
	
	blk256_mul_blk128(&rop, &z, &y);

	blk256_sub(&x, &x, &rop);
	blk256_print("x", x);

	blk256_add(&q, &q, &z);
	blk256_print("q", q);

	return 0;
}