static void testmul(void)
{
int kdone, kidx;
u32_t ilo = ex64lo(i), jlo = ex64lo(j);
u64_t prod = mul64(i, j);
int prodbits;
/* compute maximum index of highest-order bit */
prodbits = bsr64(i) + bsr64(j) + 1;
if (cmp64u(i, 0) == 0 || cmp64u(j, 0) == 0) prodbits = -1;
if (bsr64(prod) > prodbits) ERR;
/* compare to 32-bit multiplication if possible */
if (ex64hi(i) == 0 && ex64hi(j) == 0) {
if (cmp64(prod, mul64u(ilo, jlo)) != 0) ERR;
/* if there is no overflow we can check against pure 32-bit */
if (prodbits < 32 && cmp64u(prod, ilo * jlo) != 0) ERR;
}
/* in 32-bit arith low-order DWORD matches regardless of overflow */
if (ex64lo(prod) != ilo * jlo) ERR;
/* multiplication by zero yields zero */
if (prodbits < 0 && cmp64u(prod, 0) != 0) ERR;
/* if there is no overflow, check absence of zero divisors */
if (prodbits >= 0 && prodbits < 64 && cmp64u(prod, 0) == 0) ERR;
/* commutativity */
if (cmp64(prod, mul64(j, i)) != 0) ERR;
/* loop though all argument value combinations for third argument */
for (kdone = 0, kidx = 0; k = getargval(kidx, &kdone), !kdone; kidx++) {
/* associativity */
if (cmp64(mul64(mul64(i, j), k), mul64(i, mul64(j, k))) != 0) ERR;
/* left and right distributivity */
if (cmp64(mul64(add64(i, j), k), add64(mul64(i, k), mul64(j, k))) != 0) ERR;
if (cmp64(mul64(i, add64(j, k)), add64(mul64(i, j), mul64(i, k))) != 0) ERR;
}
}
unsigned bitdelta64(uint64_t *in, unsigned n, uint64_t *out, uint64_t start, unsigned inc) {
typeof(in[0]) b = 0,*op = out; BITDELTA(in, n, inc, start, b |= _x; *op++ = _x);
return bsr64(b);
}