/* 128-bit blocks and associated operations
 *
 * $ gcc -Wall -o blk128 blk128.c
 */
#include <stdlib.h>
#include <stdint.h>
#include <stdio.h>

typedef struct __blk128_t {
	char     mx; /* The 65th bit */
	uint64_t hi;
	uint64_t lo;
} blk128_t;

void blk128_add(blk128_t *blk, uint64_t x)
{
	blk->lo += x;
	if (blk->lo < x) {
		blk->hi++;
		if (!blk->hi)
			blk->mx = 1;
	}
}

#define blk128_init() (blk128_t*)malloc(sizeof(blk128_t))
#define u64(x) ((uint64_t)x)

#define blk128_print(x) \
	do {\
		printf("c: %d, hi: %lu, lo: %lu\n", x.mx, x.hi, x.lo);\
	} while(0);

/* Compose two 64 bit numbers as a 128-bit number */
void blk128_compose(blk128_t *rop, uint64_t x, uint64_t y)
{
	/* Compute x * (B + 1) + y
	 *
	 * Equivalent to x*B + x + y */
	rop->hi = x;
	rop->lo = y;
	blk128_add(rop, x);
}

int main(int argc, char *argv[])
{
	blk128_t t = {0, 0, 0};

	blk128_add(&t, 5);
	blk128_add(&t, u64(~0));
	blk128_print(t);


	/* Max it out! */
	t.hi = u64(~0);
	blk128_print(t);
	
	blk128_add(&t, u64(~0));
	blk128_print(t);

	blk128_t rop = {0, 0, 0};
	blk128_compose(&rop, 5, 7);
	blk128_print(rop);

	return 0;
}