SYSTEM INT1: Difference between revisions
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== [[SYSTEM_INT1]] ($ | == [[SYSTEM_INT1]] ($C00438): Multi-purpose VBL call == | ||
Needs to be called at the beginning of the [[68k interrupts|vblank]] period. Sets values in RAM according to buttons states, checks [[CDDA]] commands, calls [[MESS_OUT]], and probably other things... | Needs to be called at the beginning of the [[68k interrupts|vblank]] period. Sets values in RAM according to buttons states, checks [[CDDA]] commands, calls [[MESS_OUT]], and probably other things... | ||
Revision as of 18:14, 17 August 2011
SYSTEM_INT1 ($C00438): Multi-purpose VBL call
Needs to be called at the beginning of the vblank period. Sets values in RAM according to buttons states, checks CDDA commands, calls MESS_OUT, and probably other things...
If called outside of vblank, interrupts need to be disabled before.
Memory locations set (all 8bit):
BIOS_P1CURRENT ;$10FD95 Joystick 1 state BIOS_P1PREVIOUS ;$10FD96 Previous joystick 1 state BIOS_P1CHANGE ;$10FD97 Joystick 1 state change (edges) BIOS_P1REPEAT ;$10FD98 Joystick 1 repeat (edge, and strobe if held more than ? calls) BIOS_P2CURRENT ;$10FD9B Joystick 2 state BIOS_P2PREVIOUS ;$10FD9C Previous joystick 2 state BIOS_P2CHANGE ;$10FD9D Joystick 2 state change (edges) BIOS_P2REPEAT ;$10FD9E Joystick 2 repeat (edge, and strobe if held more than ? calls) BIOS_STATCURNT ;Joystick 1/2 start/select state BIOS_STATCHANGE ;Previous Joystick 1/2 start/select state
Bit definitions: see Joypad