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[reactos.git] / subsystems / mvdm / ntvdm / cpu / callback.c
1 /*
2 * COPYRIGHT: GPL - See COPYING in the top level directory
3 * PROJECT: ReactOS Virtual DOS Machine
4 * FILE: subsystems/mvdm/ntvdm/cpu/callback.c
5 * PURPOSE: 16 and 32-bit Callbacks Support
6 * PROGRAMMERS: Aleksandar Andrejevic <theflash AT sdf DOT lonestar DOT org>
7 * Hermes Belusca-Maito (hermes.belusca@sfr.fr)
8 */
9
10 /******************************************************************************\
11 | WARNING! WARNING! WARNING! WARNING! WARNING! WARNING! WARNING! WARNING!
12 |
13 | Callbacks support supposes implicitly that the callbacks are used
14 | in the SAME thread as the CPU thread, otherwise messing in parallel
15 | with the CPU registers is 100% prone to bugs!!
16 \******************************************************************************/
17
18 /* INCLUDES *******************************************************************/
19
20 #include "ntvdm.h"
21
22 #define NDEBUG
23 #include <debug.h>
24
25 #include "emulator.h"
26 #include "callback.h"
27
28 #include "cpu.h"
29 #include "bop.h"
30 #include <isvbop.h>
31
32 /* PRIVATE VARIABLES **********************************************************/
33
34 #if 0
35 /* FIXME: Are we going to use this somewhere? */
36 static BYTE Yield[] =
37 {
38 0x90, 0x90, 0x90, 0x90, 0x90, 0x90, 0x90,
39 0x90, 0x90, 0x90, 0x90, 0x90, 0x90, // 13x nop
40 BOP(BOP_UNSIMULATE), // UnSimulate16 BOP
41 };
42 C_ASSERT(sizeof(Yield) == 16 * sizeof(BYTE));
43 #endif
44
45 /* PUBLIC FUNCTIONS ***********************************************************/
46
47 VOID
48 InitializeContextEx(IN PCALLBACK16 Context,
49 IN ULONG TrampolineSize,
50 IN USHORT Segment,
51 IN USHORT Offset)
52 {
53 Context->TrampolineFarPtr = MAKELONG(Offset, Segment);
54 Context->TrampolineSize = max(TRAMPOLINE_SIZE, TrampolineSize);
55 Context->Segment = Segment;
56 Context->NextOffset = Offset + Context->TrampolineSize;
57 }
58
59 VOID
60 InitializeContext(IN PCALLBACK16 Context,
61 IN USHORT Segment,
62 IN USHORT Offset)
63 {
64 InitializeContextEx(Context,
65 TRAMPOLINE_SIZE,
66 Segment,
67 Offset);
68 }
69
70 VOID
71 Call16(IN USHORT Segment,
72 IN USHORT Offset)
73 {
74 /* Save CS:IP */
75 USHORT OrgCS = getCS();
76 USHORT OrgIP = getIP();
77
78 /* Set the new CS:IP */
79 setCS(Segment);
80 setIP(Offset);
81
82 DPRINT("Call16(%04X:%04X)\n", Segment, Offset);
83
84 /* Start CPU simulation */
85 CpuSimulate();
86
87 /* Restore CS:IP */
88 setCS(OrgCS);
89 setIP(OrgIP);
90 }
91
92 VOID
93 RunCallback16(IN PCALLBACK16 Context,
94 IN ULONG FarPtr)
95 {
96 PUCHAR TrampolineBase = (PUCHAR)FAR_POINTER(Context->TrampolineFarPtr);
97 PUCHAR Trampoline = TrampolineBase;
98 UCHAR OldTrampoline[TRAMPOLINE_SIZE];
99
100 /* Save the old trampoline */
101 ((PULONGLONG)&OldTrampoline)[0] = ((PULONGLONG)TrampolineBase)[0];
102
103 DPRINT("RunCallback16(0x%p)\n", FarPtr);
104
105 /* Build the generic entry-point for 16-bit far calls */
106 *Trampoline++ = 0x9A; // Call far seg:off
107 *(PULONG)Trampoline = FarPtr;
108 Trampoline += sizeof(ULONG);
109 UnSimulate16(Trampoline);
110
111 /* Perform the call */
112 Call16(HIWORD(Context->TrampolineFarPtr),
113 LOWORD(Context->TrampolineFarPtr));
114
115 /* Restore the old trampoline */
116 ((PULONGLONG)TrampolineBase)[0] = ((PULONGLONG)&OldTrampoline)[0];
117 }
118
119 ULONG
120 RegisterCallback16(IN ULONG FarPtr,
121 IN LPBYTE CallbackCode,
122 IN SIZE_T CallbackSize,
123 OUT PSIZE_T CodeSize OPTIONAL)
124 {
125 LPBYTE CodeStart = (LPBYTE)FAR_POINTER(FarPtr);
126 LPBYTE Code = CodeStart;
127
128 SIZE_T OurCodeSize = CallbackSize;
129
130 if (CallbackCode == NULL) CallbackSize = 0;
131
132 if (CallbackCode)
133 {
134 /* 16-bit interrupt code */
135 RtlCopyMemory(Code, CallbackCode, CallbackSize);
136 Code += CallbackSize;
137 }
138
139 /* Return the real size of the code if needed */
140 if (CodeSize) *CodeSize = OurCodeSize; // == (ULONG_PTR)Code - (ULONG_PTR)CodeStart;
141
142 // /* Return the entry-point address for 32-bit calls */
143 // return (ULONG_PTR)(CodeStart + CallbackSize);
144 return OurCodeSize;
145 }
146
147 /* EOF */