WonderWitch/FreyaBIOS/Timer

The Timer interrupt provides an abstraction layer for the WonderSwan's timers, as well as the on-cartridge RTC.

Types

RTC fields

The RTC field indexes match the order of fields returned by the RTC chip.

Note that FreyaBIOS transparently converts the values to and from BCD.

Index	Data	Format
0	Year	0 - 99; 0 is assumed to be the year 2000.
1	Month	1 - 12
2	Date (day of month)	1 - 31
3	Day of week	0 - 6; 0 = Sunday, 1 = Monday, ..., 6 = Saturday
4	Hour	0 - 23
5	Minute	0 - 59
6	Second	0 - 59

RTC struct

The RTC struct is a seven-byte memory structure, containing all RTC fields consecutively, taking up one unsinged byte each.

Interrupts

INT $16/AH=$00 - rtc_reset

AH = $00

INT $16/AH=$01 - rtc_set_datetime

AH = $01
BX = Field
CX = Value of field

INT $16/AH=$02 - rtc_get_datetime

AH = $02
BX = Field

Return:

AX = Value of field

INT $16/AH=$03 - rtc_set_datetime_struct

AH = $03
DS:DX = Pointer to RTC struct

INT $16/AH=$04 - rtc_get_datetime_struct

AH = $04
DS:DX = Pointer to RTC struct

INT $16/AH=$05 - rtc_enable_alarm

AH = $05
BL = Hour
BH = Minute

INT $16/AH=$06 - rtc_disable_alarm

AH = $06

INT $16/AH=$07 - timer_enable

AH = $07
AL = Type (0 = HBlank, 1 = VBlank)
BL = Reload mode (0 = one-shot, 1 = repeating)
CX = Time, in lines or frames, to wait.

INT $16/AH=$08 - timer_disable

AH = $08
AL = Type (0 = HBlank, 1 = VBlank)

INT $16/AH=$09 - timer_get_count

AH = $09
AL = Type (0 = HBlank, 1 = VBlank)