mirror of
https://github.com/reactos/reactos.git
synced 2024-11-04 22:00:55 +00:00
76 lines
1.8 KiB
C
76 lines
1.8 KiB
C
|
/*
|
||
|
|
* PROJECT: NEC PC-98 series HAL
|
||
|
|
* LICENSE: GPL-2.0-or-later (https://spdx.org/licenses/GPL-2.0-or-later)
|
||
|
|
* PURPOSE: PIT rollover tables
|
||
|
|
* COPYRIGHT: Copyright 2020 Dmitry Borisov (di.sean@protonmail.com)
|
||
|
|
*/
|
||
|
|
|
||
|
|
/* INCLUDES ******************************************************************/
|
||
|
|
|
||
|
|
#include <hal.h>
|
||
|
|
|
||
|
|
/* GLOBALS *******************************************************************/
|
||
|
|
|
||
|
|
#define LPT_STATUS 0x42
|
||
|
|
#define SYSTEM_CLOCK_8_MHZ 0x20
|
||
|
|
|
||
|
|
ULONG PIT_FREQUENCY;
|
||
|
|
HALP_ROLLOVER HalpRolloverTable[15];
|
||
|
|
|
||
|
|
/* Accuracy is 97.5% */
|
||
|
|
static const HALP_ROLLOVER RolloverTable1[15] =
|
||
|
|
{
|
||
|
|
{1996, 9996}, /* 1 ms */
|
||
|
|
{3993, 19997},
|
||
|
|
{5990, 29998},
|
||
|
|
{7987, 39999},
|
||
|
|
{9984, 50000},
|
||
|
|
{11980, 59996},
|
||
|
|
{13977, 69997},
|
||
|
|
{15974, 79998},
|
||
|
|
{17971, 89999},
|
||
|
|
{19968, 100000},
|
||
|
|
{21964, 109996},
|
||
|
|
{23961, 119997},
|
||
|
|
{25958, 129998},
|
||
|
|
{27955, 139999},
|
||
|
|
{29951, 149995} /* 15 ms */
|
||
|
|
};
|
||
|
|
static const HALP_ROLLOVER RolloverTable2[15] =
|
||
|
|
{
|
||
|
|
{2463, 10022}, /* 1 ms */
|
||
|
|
{4912, 19987},
|
||
|
|
{7376, 30013},
|
||
|
|
{9825, 39978},
|
||
|
|
{12288, 50000},
|
||
|
|
{14751, 60022},
|
||
|
|
{17200, 69987},
|
||
|
|
{19664, 80013},
|
||
|
|
{22113, 89978},
|
||
|
|
{24576, 100000},
|
||
|
|
{27039, 110022},
|
||
|
|
{29488, 119987},
|
||
|
|
{31952, 130013},
|
||
|
|
{34401, 139978},
|
||
|
|
{36864, 150000} /* 15 ms */
|
||
|
|
};
|
||
|
|
|
||
|
|
/* PRIVATE FUNCTIONS *********************************************************/
|
||
|
|
|
||
|
|
VOID
|
||
|
|
NTAPI
|
||
|
|
HalpInitializeClockPc98(VOID)
|
||
|
|
{
|
||
|
|
/* Obtain system clock value from the parallel port */
|
||
|
|
if (__inbyte(LPT_STATUS) & SYSTEM_CLOCK_8_MHZ)
|
||
|
|
{
|
||
|
|
PIT_FREQUENCY = TIMER_FREQUENCY_1;
|
||
|
|
RtlCopyMemory(HalpRolloverTable, RolloverTable1, sizeof(HALP_ROLLOVER) * 15);
|
||
|
|
}
|
||
|
|
else
|
||
|
|
{
|
||
|
|
PIT_FREQUENCY = TIMER_FREQUENCY_2;
|
||
|
|
RtlCopyMemory(HalpRolloverTable, RolloverTable2, sizeof(HALP_ROLLOVER) * 15);
|
||
|
|
}
|
||
|
|
}
|