This repository has been archived on 2026-04-17. You can view files and clone it. You cannot open issues or pull requests or push a commit.
Files
bhlib/src/Algo.c

412 lines
10 KiB
C

#include <BH/Algo.h>
#include <string.h>
void BH_Swap(void *dest,
void *src,
size_t size)
{
int tmp;
/* Swap bytes in int-sized chunks */
while (size >= sizeof(tmp))
{
memmove(&tmp, dest, sizeof(tmp));
memmove(dest, src, sizeof(tmp));
memmove(src, &tmp, sizeof(tmp));
dest = (char *)dest + sizeof(tmp);
src = (char *)src + sizeof(tmp);
size -= sizeof(tmp);
}
/* Swap the remaining size */
if (size)
{
memmove(&tmp, dest, size);
memmove(dest, src, size);
memmove(src, &tmp, size);
}
}
void *BH_Partition(void *pivot,
void *array,
size_t size,
size_t element,
BH_EqualCallback equal)
{
char *start, *end, *i, *j;
/* Calculate start, end and item pointers */
start = (char *)array;
end = start + size * element;
i = start;
j = start + (size - 1) * element;
/* Iterate over array */
while (1)
{
/* Find first element from the left that are bigger then pivot */
while (i < end && equal(i, pivot) < 0)
i += element;
/* Find first element from the right that are less then pivot*/
while (j >= start && equal(j, pivot) >= 0)
j -= element;
/* If item elemetns passed each other - we are done */
if (i >= j)
break;
/* Special case when pivot is actually part of the array */
if (pivot == i)
pivot = j;
else if (pivot == j)
pivot = i;
/* Swap elements and continue */
BH_Swap(i, j, element);
i += element;
j -= element;
}
/* Return pointer to the middle of the partition */
return j + element;
}
#if 0
static void BH_SortInsert(void *array,
size_t size,
size_t element,
BH_EqualCallback equal)
{
size_t i, j;
/* Standard insert sort */
for (i = 1; i < size; i++)
{
for (j = i; j >= 1; j -= 1)
{
char *lhs, *rhs;
lhs = (char *)array + j * element;
rhs = (char *)array + (j - 1) * element;
if (equal(lhs, rhs) < 0)
BH_Swap(lhs, rhs, element);
else
break;
}
}
}
#endif
static void BH_SortShell(void *array,
size_t size,
size_t element,
BH_EqualCallback equal)
{
static const size_t gaps[10] = {1750, 701, 301, 132, 57, 23, 10, 4, 1, 0};
const size_t *gap;
size_t i, j;
/* Shell sort with A102549 sequence */
for (gap = gaps; *gap; ++gap)
{
for (i = *gap; i < size; i++)
{
for (j = i; j >= *gap; j -= *gap)
{
char *lhs, *rhs;
lhs = (char *)array + j * element;
rhs = (char *)array + (j - *gap) * element;
if (equal(lhs, rhs) < 0)
BH_Swap(lhs, rhs, element);
else
break;
}
}
}
}
static void BH_SortHeap(void *array,
size_t size,
size_t element,
BH_EqualCallback equal)
{
size_t i;
BH_HeapMake(array, size, element, equal);
for (i = size; i > 0; i--)
BH_HeapRemove(array, i, element, equal);
}
static void BH_SortIntroR(void *array,
size_t size,
size_t element,
BH_EqualCallback equal,
size_t depth)
{
/* Introsort (with manual tail call optimization) */
while (1)
{
char *start, *middle, *end, *pivot;
if (size < 16)
{
/* There are less then 16 elements left - use Shell/Insert sort */
BH_SortShell(array, size, element, equal);
return;
}
else if (!depth)
{
/* Max depth reached - use heap sort */
BH_SortHeap(array, size, element, equal);
return;
}
/* Calculate start, middle and end pointers */
start = (char *)array;
middle = start + (size / 2) * element;
end = start + (size - 1) * element;
/* Select middle element */
if (equal(start, middle) > 0)
{
if (equal(middle, end) > 0)
pivot = middle;
else if (equal(start, end) > 0)
pivot = end;
else
pivot = start;
}
else
{
if (equal(start, end) > 0)
pivot = start;
else if (equal(middle, end) > 0)
pivot = end;
else
pivot = middle;
}
/* Partition the array */
middle = BH_Partition(pivot, array, size, element, equal);
/* Recursive call into first half */
BH_SortIntroR(array, (middle - start) / element, element, equal, depth - 1);
/* Setup array and size for the second half */
array = middle;
size = size - (middle - start) / element;
depth--;
}
}
void BH_Sort(void *array,
size_t size,
size_t element,
BH_EqualCallback equal)
{
size_t depth, depth_log;
/* Calculate max depth */
depth = 0;
depth_log = 1;
while (depth_log < size)
{
depth++;
depth_log <<= 1;
}
/* Call main sorting function */
BH_SortIntroR(array, size, element, equal, depth);
}
void BH_HeapMake(void *array,
size_t size,
size_t element,
BH_EqualCallback equal)
{
char *start, *end;
size_t i;
/* Calculate start and end pointers of the array */
start = (char *)array;
end = start + size * element;
/* Bottom up heapify algorithm */
for (i = size / 2 + 1; i; --i)
{
char *current, *left, *right;
/* Calculate current and children pointers */
current = start + (i - 1) * element;
left = start + (current - start) * 2 + element;
right = left + element;
while (left < end)
{
char *biggest;
/* Determine biggest child */
biggest = left;
if (right < end && equal(left, right) < 0)
biggest = right;
/* Compare biggest child with current */
if (equal(current, biggest) < 0)
{
/* Swap content and recalculate children pointers */
BH_Swap(current, biggest, element);
current = biggest;
left = start + (current - start) * 2 + element;
right = left + element;
}
else
break;
}
}
}
void BH_HeapRemove(void *array,
size_t size,
size_t element,
BH_EqualCallback equal)
{
char *start, *end, *current, *left, *right;
if (size <= 1)
return;
/* Calculate start, end and children pointers */
start = (char *)array;
end = start + (size - 1) * element;
current = start;
left = start + (current - start) * 2 + element;
right = left + element;
/* Swap first and last element */
BH_Swap(current, end, element);
/* Iterate until we reach the end */
while (left < end)
{
char *biggest;
/* Determine biggest child */
biggest = left;
if (right < end && equal(left, right) < 0)
biggest = right;
/* Compare biggest child with current */
if (equal(current, biggest) < 0)
{
/* Swap content and recalculate children pointers */
BH_Swap(current, biggest, element);
current = biggest;
left = start + (current - start) * 2 + element;
right = left + element;
}
else
break;
}
}
void BH_HeapInsert(void *value,
void *array,
size_t size,
size_t element,
BH_EqualCallback equal)
{
char *start, *end, *current;
/* Calculate begin and end pointers */
start = (char *)array;
end = start + size * element;
current = end;
/* Copy value into array */
if (value)
memmove(current, value, element);
while (current > start)
{
char *parent;
/* Calculate parent pointer */
parent = start + (((current - start) / element - 1) / 2) * element;
/* Compare current and parent */
if (equal(parent, current) < 0)
{
/* Swap current and parent */
BH_Swap(parent, current, element);
current = parent;
}
else
break;
}
}
void BH_HeapReplace(void *value,
void *array,
size_t size,
size_t element,
BH_EqualCallback equal)
{
char *start, *end, *current, *left, *right;
if (size < 1)
return;
/* Calculate start, end and children pointers */
start = (char *)array;
end = start + size * element;
current = start;
left = start + (current - start) * 2 + element;
right = left + element;
/* Copy supplied element to the first (top) position */
if (value)
memmove(current, value, element);
else
memmove(current, start + size * element, element);
/* Iterate until we reach the end */
while (left < end)
{
char *biggest;
/* Determine biggest child */
biggest = left;
if (right < end && equal(left, right) < 0)
biggest = right;
/* Compare biggest child with current */
if (equal(current, biggest) < 0)
{
/* Swap content and recalculate children pointers */
BH_Swap(current, biggest, element);
current = biggest;
left = start + (current - start) * 2 + element;
right = left + element;
}
else
break;
}
}