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 S-3511A chip. Note that the values returned by FreyaBIOS are binary numbers rather than BCD numbers - they are transparently converted when communicating with the on-cartridge RTC.

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

Initializes the RTC status register (all interrupts disabled, 24-hour mode enabled).

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)