85 lines
2.9 KiB
C
85 lines
2.9 KiB
C
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#include <c_QuickSort.h>
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/**
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* Internal macro helper to swap two arbitrary blocks of memory of given size.
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*/
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C_STATIC_FORCE_INLINE
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void c_SwapInternal(char* a, char* b, c_size_t size, void* temp) {
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if (a == b) return;
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memcpy(temp, a, size);
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memcpy(a, b, size);
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memcpy(b, temp, size);
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}
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/**
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* Chooses the median of left, center, and right elements as the pivot,
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* hides it at (right - 1), and returns a pointer to it.
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*/
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C_STATIC_FORCE_INLINE
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void* c_MedianOfThree(char* arr, long long left, long long right, c_size_t size,
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void* temp, int (*compar)(const void*, const void*)) {
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long long center = left + (right - left) / 2;
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// Order left, center, right
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if (compar(arr + (left * size), arr + (center * size)) > 0) {
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c_SwapInternal(arr + (left * size), arr + (center * size), size, temp);
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}
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if (compar(arr + (left * size), arr + (right * size)) > 0) {
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c_SwapInternal(arr + (left * size), arr + (right * size), size, temp);
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}
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if (compar(arr + (center * size), arr + (right * size)) > 0) {
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c_SwapInternal(arr + (center * size), arr + (right * size), size, temp);
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}
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// Place pivot at position (right - 1)
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c_SwapInternal(arr + (center * size), arr + ((right - 1) * size), size, temp);
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return arr + ((right - 1) * size);
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}
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/* ------------------------------------------------------------------------------------------------------------------ */
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/* */
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void c_QuickSortSub(char* arr, long long left, long long right, c_size_t size, void* temp,
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int (*compar)(const void*, const void*)) {
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// Optimization: Fallback to manual insertion sort for tiny arrays to prune deep recursion
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if (left + 10 > right) {
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// Basic Inline Insertion Sort boundary loop
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for (long long i = left + 1; i <= right; i++) {
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memcpy(temp, arr + (i * size), size);
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long long j = i;
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while (j > left && compar(arr + ((j - 1) * size), temp) > 0) {
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memcpy(arr + (j * size), arr + ((j - 1) * size), size);
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j--;
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}
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memcpy(arr + (j * size), temp, size);
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}
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return;
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}
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// Retrieve Median Pivot
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c_MedianOfThree(arr, left, right, size, temp, compar);
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long long i = left;
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long long j = right - 1;
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// Hoare Partitioning Loop
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while (1) {
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while (compar(arr + ((++i) * size), arr + ((right - 1) * size)) < 0);
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while (compar(arr + ((--j) * size), arr + ((right - 1) * size)) > 0);
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if (i < j) {
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c_SwapInternal(arr + (i * size), arr + (j * size), size, temp);
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} else {
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break;
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}
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}
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// Restore pivot to its correct final slot
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c_SwapInternal(arr + (i * size), arr + ((right - 1) * size), size, temp);
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// Recursively execute left and right segments
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c_QuickSortSub(arr, left, i - 1, size, temp, compar);
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c_QuickSortSub(arr, i + 1, right, size, temp, compar);
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}
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