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
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
|
/*++
Copyright (c) 1992 Microsoft Corporation
Module Name:
XNSUMB.C
Abstract:
Routines to service XMS Request UMB and Release UMB functions.
Also includes UMB initialization routine
Author:
William Hsieh (williamh) Created 23-Sept-1992
[Environment:]
User mode, running in the MVDM context (bop from 16bits)
[Notes:]
Revision History:
--*/
#include <xms.h>
#include "umb.h"
#include "softpc.h"
// This global variable points to the first node(lowest address) UMB list
static PXMSUMB xmsUMBHead;
static BOOL xmsIsON = FALSE;
// ------------------------------------------------------------------
// Initialization for UMB support. It create a single direction linked
// list and allocate all available UMBs.
// Input: client (AX:BX) = segment:offset of himem.sys A20State variable
//
// Output: list header, xmsUMBHead set.
//-------------------------------------------------------------------
VOID xmsInitUMB(VOID)
{
PVOID Address;
ULONG Size;
PXMSUMB xmsUMB, xmsUMBNew;
xmsUMBHead = NULL;
while (ReserveUMB(UMB_OWNER_XMS, &Address, &Size) &&
(xmsUMBNew = (PXMSUMB) malloc(sizeof(XMSUMB))) != NULL) {
// convert size in bytes to paragraphs
xmsUMBNew->Size = (WORD) (Size >> 4);
// convert linear address to paragraphs segment
xmsUMBNew->Segment = (WORD)((DWORD)Address >> 4);
xmsUMBNew->Owner = 0;
if (xmsUMBHead == NULL) {
xmsUMBHead = xmsUMBNew;
xmsUMBHead->Next = NULL;
}
else {
xmsUMBNew->Next = xmsUMB->Next;
xmsUMB->Next = xmsUMBNew;
}
xmsUMB = xmsUMBNew;
}
xmsIsON = TRUE;
pHimemA20State = (PBYTE) GetVDMAddr(getAX(), getBX());
xmsEnableA20Wrapping();
}
// This function receives control whenever there has been an UMB released
// Input: PVOID Address = the block address
// ULONG Size = the block size
VOID xmsReleaseUMBNotify(
PVOID Address,
DWORD Size
)
{
// If the block is good and xms driver is ON,
// grab the block and insert it into our xms UMB list
if (Address != NULL && Size > 0 && xmsIsON &&
ReserveUMB(UMB_OWNER_XMS, &Address, &Size)){
xmsInsertUMB(Address, Size);
}
}
// ------------------------------------------------------------------
// Insert a given UMB into the list
// Input: PVOID Address = linear address of the block to be inserted
// ULONG Size = size in byte of the block
// Output: TRUE if the block was inserted to the list successfully
// FALSE if the block wasn't inserted
//-------------------------------------------------------------------
VOID xmsInsertUMB(
PVOID Address,
ULONG Size
)
{
PXMSUMB xmsUMB, xmsUMBNew;
WORD Segment;
Segment = (WORD) ((DWORD)Address >> 4);
Size >>= 4;
xmsUMB = xmsUMBNew = xmsUMBHead;
while (xmsUMBNew != NULL && xmsUMBNew->Segment < Segment) {
xmsUMB = xmsUMBNew;
xmsUMBNew = xmsUMBNew->Next;
}
// merge it with previous block if possible
if (xmsUMB != NULL &&
xmsUMB->Owner == 0 &&
Segment == xmsUMB->Segment + xmsUMB->Size) {
xmsUMB->Size += (WORD) Size;
return;
}
// merge it with the after block if possible
if (xmsUMBNew != NULL &&
xmsUMBNew->Owner == 0 &&
xmsUMBNew->Segment == Segment + Size) {
xmsUMBNew->Size += (WORD) Size;
xmsUMBNew->Segment = Segment;
return;
}
// create a new node for the block
if ((xmsUMBNew = (PXMSUMB)malloc(sizeof(XMSUMB))) != NULL) {
xmsUMBNew->Size = (WORD) Size;
xmsUMBNew->Segment = Segment;
xmsUMBNew->Owner = 0;
if (xmsUMBHead == NULL) {
xmsUMBHead = xmsUMBNew;
xmsUMBNew->Next = NULL;
}
else {
xmsUMBNew->Next = xmsUMB->Next;
xmsUMB->Next = xmsUMBNew;
}
}
}
// ------------------------------------------------------------------
// XMS function 16, Request UMB.
// Input: (DX) = requested size in paragraphs
// Output: (AX) = 1 if succeed and
// (BX) has segment address(number) of the block
// (DX) has actual allocated size in paragraphs
// (AX) = 0 if failed and
// (BL) = 0xB0, (DX) = largest size available
// or
// (BL) = 0xB1 if no UMBs are available
//-------------------------------------------------------------------
VOID xmsRequestUMB(VOID)
{
PXMSUMB xmsUMB, xmsUMBNew;
WORD SizeRequested, SizeLargest;
xmsUMB = xmsUMBHead;
SizeRequested = getDX();
SizeLargest = 0;
while (xmsUMB != NULL) {
if (xmsUMB->Owner == 0) {
if (xmsUMB->Size >= SizeRequested) {
if((xmsUMB->Size - SizeRequested) >= XMSUMB_THRESHOLD &&
(xmsUMBNew = (PXMSUMB) malloc(sizeof(XMSUMB))) != NULL) {
xmsUMBNew->Segment = xmsUMB->Segment + SizeRequested;
xmsUMBNew->Size = xmsUMB->Size - SizeRequested;
xmsUMBNew->Next = xmsUMB->Next;
xmsUMB->Next = xmsUMBNew;
xmsUMBNew->Owner = 0;
xmsUMB->Size -= xmsUMBNew->Size;
}
xmsUMB->Owner = 0xFFFF;
setAX(1);
setBX(xmsUMB->Segment);
setDX(xmsUMB->Size);
return;
}
else {
if (xmsUMB->Size > SizeLargest)
SizeLargest = xmsUMB->Size;
}
}
xmsUMB = xmsUMB->Next;
}
setAX(0);
setDX(SizeLargest);
if (SizeLargest > 0)
setBL(0xB0);
else
setBL(0xB1);
}
//------------------------------------------------------------------
// XMS function 17, Release UMB.
// Input : (DX) = segment to be released
// Output: (AX) = 1 if succeed
// (AX) = 0 if failed and
// (BL) = 0xB2 if segment not found in the list
//------------------------------------------------------------------
VOID xmsReleaseUMB(VOID)
{
PXMSUMB xmsUMB, xmsUMBNext;
WORD Segment;
xmsUMB = xmsUMBHead;
Segment = getDX();
while (xmsUMB != NULL && xmsUMB->Segment != Segment) {
xmsUMB = xmsUMB->Next;
}
if (xmsUMB != NULL && xmsUMB->Owner != 0) {
xmsUMB->Owner = 0;
// no walk through the entire list to combine consecutive
// blocks together
xmsUMB = xmsUMBHead;
while (xmsUMB != NULL) {
while (xmsUMB->Owner == 0 &&
(xmsUMBNext = xmsUMB->Next) != NULL &&
xmsUMBNext->Owner == 0 &&
(WORD)(xmsUMB->Segment + xmsUMB->Size) == xmsUMBNext->Segment){
xmsUMB->Size += xmsUMBNext->Size;
xmsUMB->Next = xmsUMBNext->Next;
free(xmsUMBNext);
}
xmsUMB = xmsUMB->Next;
}
setAX(1);
}
else {
setBL(0xB2);
setAX(0);
}
}
|
