#include <linux/module.h>

/*
 * Verification test for div64_s64.
 */

#ifndef abs64
#define abs64(x) ({			\
	s64 __x = (x);			\
	(__x < 0) ? -__x : __x;		\
})
#endif

int div64_s64_test(void)
{
	s64 u, v, q, r;
	int n, i, j, k, errors = 0;
	const s64 tabs[] = {
	    0, 1, 2, 3, 4, 5, 6, 7, 8, 9,
	    10, 11, 12, 13, 14, 15, 16, 1000, 2003,
	    32765, 32766, 32767, 32768, 32769, 32760,
	    65533, 65534, 65535, 65536, 65537, 65538,
	    0x7ffffffeLL, 0x7fffffffLL, 0x80000000LL, 0x80000001LL,
	    0x7000000000000000LL, 0x7000000080000000LL, 0x7000000080000001LL,
	    0x7fffffffffffffffLL, 0x7fffffff8fffffffLL, 0x7fffffff8ffffff1LL,
	    0x7fffffff00000000LL, 0x7fffffff80000000LL, 0x7fffffff00000001LL,
	    0x0123456789abcdefLL, 0x00000000abcdef01LL, 0x0000000012345678LL,
	};

	printk("%s", "Testing signed 64-bit division.\n");
	n = sizeof(tabs) / sizeof(tabs[0]);
	for (i = 0; i < n; i++) {
		for (j = 1; j < n; j++) {
			for (k = 0; k <= 3; k++) {
				u = (k & 1)  ? -tabs[i] : tabs[i];
				v = (k >= 2) ? -tabs[j] : tabs[j];

				q = div64_s64(u, v);
				r = u - q * v;
				if (abs64(q) >  abs64(u) ||
				    abs64(r) >= abs64(v) ||
				    (r != 0 && (r ^ u) < 0)) {
					printk("%016llx/%016llx != %016llx "
					    "rem %016llx\n", u, v, q, r);
					errors++;
				}
			}
		}
	}

	if (errors) {
		printk("Failed %d/%d tests\n", errors, n * (n - 1));
	} else {
		printk("Passed all %d tests\n", n * (n - 1));
	}

	return 0;
}

void div64_s64_exit(void) { }

module_init(div64_s64_test);
module_exit(div64_s64_exit);