2 * 8253/8254 Programmable Interval Timer (PIT) emulation
4 * Copyright 2003 Jukka Heinonen
6 * This library is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU Lesser General Public
8 * License as published by the Free Software Foundation; either
9 * version 2.1 of the License, or (at your option) any later version.
11 * This library is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 * Lesser General Public License for more details.
16 * You should have received a copy of the GNU Lesser General Public
17 * License along with this library; if not, write to the Free Software
18 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
24 #include "wine/debug.h"
28 WINE_DEFAULT_DEBUG_CHANNEL(int);
31 * FIXME: Use QueryPerformanceCounter for
32 * more precise GetTimer implementation.
33 * FIXME: Use QueryPerformanceCounter (or GetTimer implementation)
34 * in timer tick routine to compensate for lost ticks.
35 * This should also make it possible to
36 * emulate really fast timers.
37 * FIXME: Support special timer modes in addition to periodic mode.
38 * FIXME: Make sure that there are only limited number
39 * of pending timer IRQ events queued. This makes sure that
40 * timer handling does not eat all available memory even
41 * if IRQ handling stops for some reason (suspended process?).
42 * This is easy to do by using DOSRELAY parameter.
43 * FIXME: Use timeSetEvent, NtSetEvent or timer thread for more precise
45 * FIXME: Move Win16 timer emulation code here.
48 /* The PC clocks ticks at 1193180 Hz. */
49 #define TIMER_FREQ 1193180
51 /* Unique system timer identifier. */
52 static UINT_PTR TIMER_id = 0;
54 /* Time when timer IRQ was last queued. */
55 static DWORD TIMER_stamp = 0;
57 /* Timer ticks between timer IRQs. */
58 static UINT TIMER_ticks = 0;
61 /***********************************************************************
64 static void CALLBACK TIMER_TimerProc( HWND hwnd,
70 DOSVM_QueueEvent( 0, DOS_PRIORITY_REALTIME, NULL, NULL );
74 /***********************************************************************
77 static void WINAPI TIMER_DoSetTimer( ULONG_PTR arg )
79 INT millis = MulDiv( arg, 1000, TIMER_FREQ );
81 /* sanity check - too fast timer */
85 TRACE_(int)( "setting timer tick delay to %d ms\n", millis );
88 KillTimer( NULL, TIMER_id );
90 TIMER_id = SetTimer( NULL, 0, millis, TIMER_TimerProc );
91 TIMER_stamp = GetTickCount();
96 /***********************************************************************
99 UINT WINAPI DOSVM_GetTimer( void )
101 if (!DOSVM_IsWin16())
103 DWORD millis = GetTickCount() - TIMER_stamp;
104 INT ticks = MulDiv( millis, TIMER_FREQ, 1000 );
106 /* sanity check - tick wrap or suspended process or update race */
107 if (ticks < 0 || ticks >= TIMER_ticks)
117 /***********************************************************************
120 void WINAPI DOSVM_SetTimer( UINT ticks )
122 if (!DOSVM_IsWin16())
123 MZ_RunInThread( TIMER_DoSetTimer, ticks );
127 /***********************************************************************
130 * DOS interrupt 08h handler (IRQ0 - TIMER).
132 void WINAPI DOSVM_Int08Handler( CONTEXT86 *context )
134 BIOSDATA *bios_data = DOSVM_BiosData();
135 CONTEXT86 nested_context = *context;
136 FARPROC16 int1c_proc = DOSVM_GetRMHandler( 0x1c );
138 nested_context.SegCs = SELECTOROF(int1c_proc);
139 nested_context.Eip = OFFSETOF(int1c_proc);
142 * Update BIOS ticks since midnight.
144 * FIXME: What to do when number of ticks exceeds ticks per day?
149 * If IRQ is called from protected mode, convert
150 * context into VM86 context. Stack is invalidated so
151 * that DPMI_CallRMProc allocates a new stack.
153 if (!ISV86(&nested_context))
155 nested_context.EFlags |= V86_FLAG;
156 nested_context.SegSs = 0;
160 * Call interrupt 0x1c.
162 DPMI_CallRMProc( &nested_context, NULL, 0, TRUE );
164 DOSVM_AcknowledgeIRQ( context );