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LibC: Implement qsort_r

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This is not really required by anything but i've seen few ports
optionally use it if available. This was trivial to implement so why not
add it :^)
This commit is contained in:
Bananymous
2026-07-05 01:55:57 +03:00
parent 58c58bcccf
commit 3e16e69602
2 changed files with 17 additions and 6 deletions
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22
userspace/libraries/LibC/stdlib.cpp
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@@ -566,7 +566,8 @@ struct qsort_pair
uint8_t* gt;
};
static qsort_pair qsort_partition(uint8_t* pbegin, uint8_t* pend, size_t width, int (*compar)(const void*, const void*))
template<typename... Args>
static qsort_pair qsort_partition(uint8_t* pbegin, uint8_t* pend, size_t width, int (*compar)(const void*, const void*, Args...), Args... args)
{
uint8_t* pivot = pbegin + (pend - pbegin) / width / 2 * width;
@@ -576,7 +577,7 @@ static qsort_pair qsort_partition(uint8_t* pbegin, uint8_t* pend, size_t width,
while (eq < gt)
{
const int comp = (eq == pivot) ? 0 : compar(eq, pivot);
const int comp = (eq == pivot) ? 0 : compar(eq, pivot, args...);
if (comp < 0)
{
@@ -602,13 +603,14 @@ static qsort_pair qsort_partition(uint8_t* pbegin, uint8_t* pend, size_t width,
return { lt, gt };
}
static void qsort_impl(uint8_t* pbegin, uint8_t* pend, size_t width, int (*compar)(const void*, const void*))
template<typename... Args>
static void qsort_impl(uint8_t* pbegin, uint8_t* pend, size_t width, int (*compar)(const void*, const void*, Args...), Args... args)
{
if (pbegin + width >= pend)
return;
auto [lt, gt] = qsort_partition(pbegin, pend, width, compar);
qsort_impl(pbegin, lt, width, compar);
qsort_impl(gt, pend, width, compar);
auto [lt, gt] = qsort_partition(pbegin, pend, width, compar, args...);
qsort_impl(pbegin, lt, width, compar, args...);
qsort_impl(gt, pend, width, compar, args...);
}
void qsort(void* base, size_t nel, size_t width, int (*compar)(const void*, const void*))
@@ -619,6 +621,14 @@ void qsort(void* base, size_t nel, size_t width, int (*compar)(const void*, cons
qsort_impl(pbegin, pbegin + nel * width, width, compar);
}
void qsort_r(void* base, size_t nel, size_t width, int (*compar)(const void*, const void*, void*), void* arg)
{
if (width == 0 || nel <= 1)
return;
uint8_t* pbegin = static_cast<uint8_t*>(base);
qsort_impl(pbegin, pbegin + nel * width, width, compar, arg);
}
// Constants and algorithm from https://en.wikipedia.org/wiki/Permuted_congruential_generator
static constexpr uint64_t s_rand_multiplier = 6364136223846793005;