/* heap sort, based on Matt Mackall's linux kernel version */
static void sort(void *base0, size_t num, size_t size, struct fdisk_context *cxt,
int (*cmp_func)(struct fdisk_context *, const void *, const void *))
{
/* pre-scale counters for performance */
int i = (num/2 - 1) * size;
size_t n = num * size, c, r;
char *base = base0;
/* heapify */
for ( ; i >= 0; i -= size) {
for (r = i; r * 2 + size < n; r = c) {
c = r * 2 + size;
if (c < n - size &&
cmp_func(cxt, base + c, base + c + size) < 0)
c += size;
if (cmp_func(cxt, base + r, base + c) >= 0)
break;
generic_swap(base + r, base + c, size);
}
}
/* sort */
for (i = n - size; i > 0; i -= size) {
generic_swap(base, base + i, size);
for (r = 0; r * 2 + size < (size_t) i; r = c) {
c = r * 2 + size;
if (c < i - size &&
cmp_func(cxt, base + c, base + c + size) < 0)
c += size;
if (cmp_func(cxt, base + r, base + c) >= 0)
break;
generic_swap(base + r, base + c, size);
}
}
}
/**
* sort - sort an array of elements
* @base: pointer to data to sort
* @num: number of elements
* @size: size of each element
* @cmp: pointer to comparison function
* @swap: pointer to swap function or NULL
*
* This function does a heapsort on the given array. You may provide a
* swap function optimized to your element type.
*
* Sorting time is O(n log n) both on average and worst-case. While
* qsort is about 20% faster on average, it suffers from exploitable
* O(n*n) worst-case behavior and extra memory requirements that make
* it less suitable for kernel use.
*/
void
sort (void *base, unsigned int *index, size_t num, size_t size,
int (*cmp) (const void *, const void *),
void (*swap) (void *, void *, int size))
{
/* pre-scale counters for performance */
// ssize_t i = (num/2 - 1) * size, n = num * size, c, r;
long i = (num / 2 - 1) * size, idxi = (num / 2 - 1) * sizeof(unsigned int);
long n = num * size, idxn = num * sizeof(unsigned int), idxc, idxr, c, r;
void *idx = (void *)index;
if (!swap)
swap = (size == 4 ? u32_swap : generic_swap);
/* heapify */
for ( ; i >= 0; i -= size, idxi -= sizeof(unsigned int)) {
for (r = i, idxr = idxi; r * 2 + size < n; r = c, idxr = idxc) {
c = r * 2 + size;
idxc = idxr * 2 + sizeof(unsigned int);
if (c < n - size && cmp (base + c, base + c + size) < 0) {
c += size;
idxc += sizeof(unsigned int);
}
if (cmp (base + r, base + c) >= 0)
break;
swap (base + r, base + c, size);
generic_swap (idx + idxr, idx + idxc, sizeof(unsigned int));
}
}
/* sort */
for (i = n - size, idxi = idxn - sizeof(unsigned int); i > 0;
i -= size, idxi -= sizeof(unsigned int)) {
swap (base, base + i, size);
generic_swap (idx, idx + idxi, sizeof(unsigned int));
for (r = 0, idxr = 0; r * 2 + size < i; r = c, idxr = idxc) {
c = r * 2 + size;
idxc = idxr * 2 + sizeof(unsigned int);
if (c < i - size && cmp (base + c, base + c + size) < 0) {
c += size;
idxc += sizeof(unsigned int);
}
if (cmp (base + r, base + c) >= 0)
break;
swap (base + r, base + c, size);
generic_swap (idx + idxr, idx + idxc, sizeof(unsigned int));
}
}
}
