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#define SWAP(x, y) do { x ^= y; y ^= x; x ^= y; } while (0)
#define MIN(x, y) ((x) < (y) ? (x) : (y))
#define MAX(x, y) ((x) > (y) ? (x) : (y))
#define DIV_ROUND_UP(n, d) (((n) + (d) - 1) / (d))
STATIC int64_t permtoindex(size_t, const uint8_t *);
STATIC void indextoperm(int64_t, size_t, uint8_t *);
STATIC int permsign(size_t, const uint8_t *);
STATIC int64_t digitstosumzero(size_t, const uint8_t *, uint8_t);
STATIC void sumzerotodigits(int64_t, size_t, uint8_t, uint8_t *);
STATIC double intpow(double, uint64_t);
/* This code is only used for assertions in debug mode */
#ifdef DEBUG
STATIC bool isperm(size_t, const uint8_t *);
STATIC bool
isperm(size_t n, const uint8_t *a)
{
size_t i;
bool aux[FACTORIAL_MAX+1];
memset(aux, false, n);
for (i = 0; i < n; i++) {
if (a[i] >= n)
return false;
else
aux[a[i]] = true;
}
for (i = 0; i < n; i++)
if (!aux[i])
return false;
return true;
}
#endif
STATIC int64_t
permtoindex(size_t n, const uint8_t *a)
{
size_t i, j;
int64_t c, ret;
DBG_ASSERT(n <= FACTORIAL_MAX, "Error: cannot compute permtoindex() "
"for set of size %zu > %" PRId64 "\n", n, FACTORIAL_MAX);
DBG_ASSERT(isperm(n, a), "Error: cannot compute permtoindex() for "
"invalid permutation\n");
for (i = 0, ret = 0; i < n; i++) {
for (j = i+1, c = 0; j < n; j++)
c += (a[i] > a[j]) ? 1 : 0;
ret += factorial[n-i-1] * c;
}
return ret;
}
STATIC void
indextoperm(int64_t p, size_t n, uint8_t *r)
{
int64_t c;
size_t i, j;
uint8_t a[FACTORIAL_MAX+1];
DBG_ASSERT(n <= FACTORIAL_MAX, "Error: cannot compute indextoperm() "
"for set of size %zu > %" PRId64 "\n", n, FACTORIAL_MAX);
DBG_ASSERT(p >= 0 && p < factorial[n], "Error: invalid permutation "
"index %" PRId64 " for set of size %zu\n", p, n);
memset(a, 0, n);
for (i = 0; i < n; i++) {
for (j = 0, c = 0; c <= p / factorial[n-i-1]; j++)
c += a[j] ? 0 : 1;
r[i] = j-1;
a[j-1] = 1;
p %= factorial[n-i-1];
}
return;
}
STATIC int
permsign(size_t n, const uint8_t *a)
{
size_t i, j, ret;
for (i = 0, ret = 0; i < n; i++)
for (j = i+1; j < n; j++)
ret += a[i] > a[j] ? 1 : 0;
return ret % 2;
}
STATIC int64_t
digitstosumzero(size_t n, const uint8_t *a, uint8_t b)
{
int64_t ret, p;
size_t i, sum;
DBG_ASSERT((n == 8 && b == 3 ) || (n == 12 && b == 2),
"Error: digitstosumzero() called with n=%zu and b=%" PRIu8
" (use n=8 b=3 or n=12 b=2)\n", n, b);
for (i = 1, ret = 0, p = 1, sum = 0; i < n; i++, p *= (int64_t)b) {
DBG_ASSERT(a[i] < b, "Error: digit %" PRIu8
" > %" PRIu8 "in digitstosumzero()\n", a[i], b);
sum += a[i];
ret += p * (int64_t)a[i];
}
return ret;
}
STATIC void
sumzerotodigits(int64_t d, size_t n, uint8_t b, uint8_t *a)
{
uint8_t sum;
size_t i;
DBG_ASSERT((n == 8 && b == 3 ) || (n == 12 && b == 2),
"Error: sumzerotodigits() called with n=%zu and b=%" PRIu8
" (use n=8 b=3 or n=12 b=2)\n", n, b);
for (i = 1, sum = 0; i < n; i++, d /= (int64_t)b) {
a[i] = (uint8_t)(d % (int64_t)b);
sum += a[i];
}
a[0] = (b - (sum % b)) % b;
return;
}
STATIC double
intpow(double b, uint64_t e)
{
double r;
if (e == 0)
return 1;
r = intpow(b, e/2);
return e % 2 == 0 ? r * r : b * r * r;
}
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