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MS-DOS-kernel/kernel/sysclk.c at master · Programuserbash/MS-DOS-kernel · GitHub
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/****************************************************************/
/* */
/* sysclk.c */
/* */
/* System Clock Driver */
/* */
/* Copyright (c) 1995 */
/* Pasquale J. Villani */
/* All Rights Reserved */
/* */
/* This file is part of DOS-C. */
/* */
/* DOS-C is free software; you can redistribute it and/or */
/* modify it under the terms of the GNU General Public License */
/* as published by the Free Software Foundation; either version */
/* 2, or (at your option) any later version. */
/* */
/* DOS-C is distributed in the hope that it will be useful, but */
/* WITHOUT ANY WARRANTY; without even the implied warranty of */
/* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See */
/* the GNU General Public License for more details. */
/* */
/* You should have received a copy of the GNU General Public */
/* License along with DOS-C; see the file COPYING. If not, */
/* write to the Free Software Foundation, 675 Mass Ave, */
/* Cambridge, MA 02139, USA. */
/****************************************************************/
#include
"portab.h"
#include
"globals.h"
#ifdef
VERSION_STRINGS
static
char
*
RcsId
=
"$Id: sysclk.c 681 2003-09-09 17:32:20Z bartoldeman $"
;
#endif
/* */
/* WARNING - THIS DRIVER IS NON-PORTABLE!!!! */
/* */
UWORD
ASM
DaysSinceEpoch
=
0
;
typedef
UDWORD
ticks_t
;
STATIC
int
ByteToBcd
(
int
x
)
{
return
((
x
/
10
) <<
4
) | (
x
%
10
);
}
/*
STATIC int BcdToByte(int x)
{
return ((x >> 4) & 0xf) * 10 + (x & 0xf);
}
*/
STATIC
void
DayToBcd
(
BYTE
*
x
,
unsigned
mon
,
unsigned
day
,
unsigned
yr
)
{
x
[
1
]
=
ByteToBcd
(
mon
);
x
[
0
]
=
ByteToBcd
(
day
);
x
[
3
]
=
ByteToBcd
(
yr
/
100
);
x
[
2
]
=
ByteToBcd
(
yr
%
100
);
}
WORD
ASMCFUNC
FAR
clk_driver
(
rqptr
rp
)
{
BYTE
bcd_days
[
4
],
bcd_minutes
,
bcd_hours
,
bcd_seconds
;
switch
(
rp
->
r_command
)
{
case
C_INIT
:
/* done in initclk.c */
/* rp->r_endaddr = device_end(); not needed - bart */
rp
->
r_nunits
=
0
;
return
S_DONE
;
case
C_INPUT
:
{
struct
ClockRecord
clk
;
int
tmp
;
ticks_t
ticks
;
if
(
sizeof
(
struct
ClockRecord
)
!=
rp
->
r_count
)
return
failure
(
E_LENGTH
);
/* The scaling factor is now
6553600/1193180 = 327680/59659 = 65536*5/59659 */
ticks
=
5
*
ReadPCClock
();
ticks
=
((
ticks
/
59659u
) <<
16
)
+
((
ticks
%
59659u
) <<
16
) /
59659u
;
tmp
=
(
int
)(
ticks
/
6000
);
clk
.
clkHours
=
tmp
/
60
;
clk
.
clkMinutes
=
tmp
%
60
;
tmp
=
(
int
)(
ticks
%
6000
);
clk
.
clkSeconds
=
tmp
/
100
;
clk
.
clkHundredths
=
tmp
%
100
;
clk
.
clkDays
=
DaysSinceEpoch
;
fmemcpy
(
rp
->
r_trans
,
&
clk
,
sizeof
(
struct
ClockRecord
));
}
return
S_DONE
;
case
C_OUTPUT
:
{
const
unsigned short
*
pdays
;
unsigned
Day
,
Month
,
Year
;
struct
ClockRecord
clk
;
ticks_t
hs
,
Ticks
;
if
(
sizeof
(
struct
ClockRecord
)
!=
rp
->
r_count
)
return
failure
(
E_LENGTH
);
fmemcpy
(
&
clk
,
rp
->
r_trans
,
sizeof
(
struct
ClockRecord
));
/* Set PC Clock first */
DaysSinceEpoch
=
clk
.
clkDays
;
hs
=
6000
*
(
ticks_t
)(
60
*
clk
.
clkHours
+
clk
.
clkMinutes
)
+
(
ticks_t
)(
100
*
clk
.
clkSeconds
+
clk
.
clkHundredths
);
/* The scaling factor is now
1193180/6553600 = 59659/327680 = 59659/65536/5 */
Ticks
=
((
hs
>>
16
)
*
59659u
+
(((
hs
&
0xffff
)
*
59659u
) >>
16
)) /
5
;
WritePCClock
(
Ticks
);
/* Now set AT clock */
/* Fix year by looping through each year, subtracting */
/* the appropriate number of days for that year. */
for
(
Year
=
1980
,
Day
=
clk
.
clkDays
;;)
{
pdays
=
is_leap_year_monthdays
(
Year
);
if
(
Day
>=
pdays
[
12
])
{
++
Year
;
Day
-=
pdays
[
12
];
}
else
break
;
}
/* Day contains the days left and count the number of */
/* days for that year. Use this to index the table. */
for
(
Month
=
1
;
Month
<
13
;
++
Month
)
{
if
(
pdays
[
Month
]
>
Day
)
{
Day
=
Day
-
pdays
[
Month
-
1
]
+
1
;
break
;
}
}
DayToBcd
(
bcd_days
,
Month
,
Day
,
Year
);
bcd_minutes
=
ByteToBcd
(
clk
.
clkMinutes
);
bcd_hours
=
ByteToBcd
(
clk
.
clkHours
);
bcd_seconds
=
ByteToBcd
(
clk
.
clkSeconds
);
WriteATClock
(
bcd_days
,
bcd_hours
,
bcd_minutes
,
bcd_seconds
);
}
return
S_DONE
;
case
C_OFLUSH
:
case
C_IFLUSH
:
return
S_DONE
;
case
C_OUB
:
case
C_NDREAD
:
case
C_OSTAT
:
case
C_ISTAT
:
default
:
return
failure
(
E_FAILURE
);
/* general failure */
}
}
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