mirror of https://github.com/acidanthera/audk.git
118 lines
3.6 KiB
C
118 lines
3.6 KiB
C
/** @file
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Math worker functions.
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Copyright (c) 2021, Intel Corporation. All rights reserved.<BR>
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SPDX-License-Identifier: BSD-2-Clause-Patent
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**/
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#include "BaseLibInternals.h"
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/**
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This function is identical to perform QuickSort,
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except that is uses the pre-allocated buffer so the in place sorting does not need to
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allocate and free buffers constantly.
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Each element must be equal sized.
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if BufferToSort is NULL, then ASSERT.
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if CompareFunction is NULL, then ASSERT.
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if BufferOneElement is NULL, then ASSERT.
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if ElementSize is < 1, then ASSERT.
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if Count is < 2 then perform no action.
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@param[in, out] BufferToSort on call a Buffer of (possibly sorted) elements
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on return a buffer of sorted elements
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@param[in] Count the number of elements in the buffer to sort
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@param[in] ElementSize Size of an element in bytes
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@param[in] CompareFunction The function to call to perform the comparison
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of any 2 elements
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@param[out] BufferOneElement Caller provided buffer whose size equals to ElementSize.
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It's used by QuickSort() for swapping in sorting.
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**/
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VOID
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EFIAPI
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QuickSort (
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IN OUT VOID *BufferToSort,
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IN CONST UINTN Count,
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IN CONST UINTN ElementSize,
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IN BASE_SORT_COMPARE CompareFunction,
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OUT VOID *BufferOneElement
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)
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{
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VOID *Pivot;
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UINTN LoopCount;
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UINTN NextSwapLocation;
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ASSERT (BufferToSort != NULL);
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ASSERT (CompareFunction != NULL);
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ASSERT (BufferOneElement != NULL);
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ASSERT (ElementSize >= 1);
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if (Count < 2) {
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return;
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}
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NextSwapLocation = 0;
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//
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// pick a pivot (we choose last element)
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//
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Pivot = ((UINT8 *)BufferToSort + ((Count - 1) * ElementSize));
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//
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// Now get the pivot such that all on "left" are below it
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// and everything "right" are above it
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//
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for (LoopCount = 0; LoopCount < Count -1; LoopCount++) {
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//
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// if the element is less than or equal to the pivot
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//
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if (CompareFunction ((VOID *)((UINT8 *)BufferToSort + ((LoopCount) * ElementSize)), Pivot) <= 0) {
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//
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// swap
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//
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CopyMem (BufferOneElement, (UINT8 *)BufferToSort + (NextSwapLocation * ElementSize), ElementSize);
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CopyMem ((UINT8 *)BufferToSort + (NextSwapLocation * ElementSize), (UINT8 *)BufferToSort + ((LoopCount) * ElementSize), ElementSize);
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CopyMem ((UINT8 *)BufferToSort + ((LoopCount)*ElementSize), BufferOneElement, ElementSize);
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//
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// increment NextSwapLocation
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//
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NextSwapLocation++;
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}
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}
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//
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// swap pivot to it's final position (NextSwapLocation)
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//
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CopyMem (BufferOneElement, Pivot, ElementSize);
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CopyMem (Pivot, (UINT8 *)BufferToSort + (NextSwapLocation * ElementSize), ElementSize);
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CopyMem ((UINT8 *)BufferToSort + (NextSwapLocation * ElementSize), BufferOneElement, ElementSize);
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//
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// Now recurse on 2 partial lists. neither of these will have the 'pivot' element
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// IE list is sorted left half, pivot element, sorted right half...
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//
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if (NextSwapLocation >= 2) {
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QuickSort (
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BufferToSort,
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NextSwapLocation,
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ElementSize,
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CompareFunction,
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BufferOneElement
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);
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}
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if ((Count - NextSwapLocation - 1) >= 2) {
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QuickSort (
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(UINT8 *)BufferToSort + (NextSwapLocation + 1) * ElementSize,
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Count - NextSwapLocation - 1,
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ElementSize,
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CompareFunction,
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BufferOneElement
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);
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}
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}
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