summaryrefslogtreecommitdiff
path: root/ShellPkg/Library/BaseSortLib/BaseSortLib.c
blob: a7b37a0f550573a3c7b9a5b8e178731ab155fe38 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
/** @file
  Library used for sorting routines.

Copyright (c) 2009, Intel Corporation<BR>
All rights reserved. This program and the accompanying materials
are licensed and made available under the terms and conditions of the BSD License
which accompanies this distribution.  The full text of the license may be found at
http://opensource.org/licenses/bsd-license.php

THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.

**/

#include <Uefi.h>

#include <Library/BaseLib.h>
#include <Library/BaseMemoryLib.h>
#include <Library/DebugLib.h>
#include <Library/MemoryAllocationLib.h>
#include <Library/SortLib.h> 

/**
  Worker function for QuickSorting.  This function is identical to PerformQuickSort, 
  except that is uses the pre-allocated buffer so the in place sorting does not need to 
  allocate and free buffers constantly.

  Each element must be equal sized.

  if BufferToSort is NULL, then ASSERT.
  if CompareFunction is NULL, then ASSERT.
  if Buffer is NULL, then ASSERT.

  if Count is < 2 then perform no action.
  if Size is < 1 then perform no action.

  @param[in,out] BufferToSort   on call a Buffer of (possibly sorted) elements
                                on return a buffer of sorted elements
  @param[in] Count              the number of elements in the buffer to sort
  @param[in] ElementSize        Size of an element in bytes
  @param[in] CompareFunction    The function to call to perform the comparison 
                                of any 2 elements
  @param[in] Buffer             Buffer of size ElementSize for use in swapping
**/
VOID
EFIAPI
QuickSortWorker (
  IN OUT VOID                           *BufferToSort,
  IN CONST UINTN                        Count,
  IN CONST UINTN                        ElementSize,
  IN       SORT_COMPARE                 CompareFunction,
  IN VOID                               *Buffer
  )
{
  VOID        *Pivot;
  UINTN       LoopCount;
  UINTN       NextSwapLocation;

  ASSERT(BufferToSort     != NULL);
  ASSERT(CompareFunction  != NULL);
  ASSERT(Buffer  != NULL);

  if ( Count < 2 
    || ElementSize  < 1
    ){
    return;
  }

  NextSwapLocation = 0;

  //
  // pick a pivot (we choose last element)
  //
  Pivot = ((UINT8*)BufferToSort+((Count-1)*ElementSize));

  //
  // Now get the pivot such that all on "left" are below it
  // and everything "right" are above it
  //
  for ( LoopCount = 0
      ; LoopCount < Count -1 
      ; LoopCount++
      ){
    //
    // if the element is less than the pivot
    //
    if (CompareFunction((VOID*)((UINT8*)BufferToSort+((LoopCount)*ElementSize)),Pivot) <= 0){
      //
      // swap 
      //
      CopyMem (Buffer, (UINT8*)BufferToSort+(NextSwapLocation*ElementSize), ElementSize);
      CopyMem ((UINT8*)BufferToSort+(NextSwapLocation*ElementSize), (UINT8*)BufferToSort+((LoopCount)*ElementSize), ElementSize);
      CopyMem ((UINT8*)BufferToSort+((LoopCount)*ElementSize), Buffer, ElementSize);

      //
      // increment NextSwapLocation
      // 
      NextSwapLocation++;
    }
  }
  //
  // swap pivot to it's final position (NextSwapLocaiton)
  //
  CopyMem (Buffer, Pivot, ElementSize);
  CopyMem (Pivot, (UINT8*)BufferToSort+(NextSwapLocation*ElementSize), ElementSize);
  CopyMem ((UINT8*)BufferToSort+(NextSwapLocation*ElementSize), Buffer, ElementSize);

  //
  // Now recurse on 2 paritial lists.  neither of these will have the 'pivot' element 
  // IE list is sorted left half, pivot element, sorted right half...
  //
  QuickSortWorker(
    BufferToSort, 
    NextSwapLocation, 
    ElementSize, 
    CompareFunction,
    Buffer);

  QuickSortWorker(
    (UINT8 *)BufferToSort + (NextSwapLocation+1) * ElementSize,
    Count - NextSwapLocation - 1, 
    ElementSize, 
    CompareFunction,
    Buffer);

  return;
}
/**
  Function to perform a Quick Sort alogrithm on a buffer of comparable elements.

  Each element must be equal sized.

  if BufferToSort is NULL, then ASSERT.
  if CompareFunction is NULL, then ASSERT.

  if Count is < 2 then perform no action.
  if Size is < 1 then perform no action.

  @param[in,out] BufferToSort   on call a Buffer of (possibly sorted) elements
                                on return a buffer of sorted elements
  @param[in] Count              the number of elements in the buffer to sort
  @param[in] ElementSize        Size of an element in bytes
  @param[in] CompareFunction    The function to call to perform the comparison 
                                of any 2 elements
**/
VOID
EFIAPI
PerformQuickSort (
  IN OUT VOID                           *BufferToSort,
  IN CONST UINTN                        Count,
  IN CONST UINTN                        ElementSize,
  IN       SORT_COMPARE                 CompareFunction
  )
{
  VOID  *Buffer;

  ASSERT(BufferToSort     != NULL);
  ASSERT(CompareFunction  != NULL);

  Buffer = AllocatePool(ElementSize);
  ASSERT(Buffer != NULL);

  QuickSortWorker(
    BufferToSort,
    Count,
    ElementSize,
    CompareFunction,
    Buffer);

  FreePool(Buffer);
  return;
}

/**
  Not supported in Base version.
  
  ASSERT and return 0.
**/
INTN
DevicePathCompare (
  IN  CONST VOID             *Buffer1,
  IN  CONST VOID             *Buffer2
  )
{
  ASSERT(FALSE);
  return 0;
}

/**
  Function to compare 2 strings without regard to case of the characters.

  @param[in] Buffer1            Pointer to String to compare.
  @param[in] Buffer2            Pointer to second String to compare.

  @retval 0                     Buffer1 equal to Buffer2.
  @return < 0                   Buffer1 is less than Buffer2.
  @return > 0                   Buffer1 is greater than Buffer2.                 
**/
INTN
EFIAPI
StringNoCaseCompare (
  IN  CONST VOID             *Buffer1,
  IN  CONST VOID             *Buffer2
  )
{
  ASSERT(FALSE);
  return 0;
}