BIOS.asm

;--------------------------------------------------------
;           COPYRIGHT (C) HARRY CLARK 2024
;--------------------------------------------------------
;           GENERIC SEGA MEGA CD LOADER
;--------------------------------------------------------
;          THIS FILE PERTAINS TO THE BIOS
;       FUNCTIONALITY - DECLARING AND ACCESSING
;     THIS SUB-ROUTINES FOR THE CPU TO BOOT THE DISC
;--------------------------------------------------------

    INCLUDE     "BIOS_inc.asm"
    INCLUDE     "macros.asm"
    ORG $6000

;--------------------------------------------------------
;       DETERMINE THE VALUES NECESSARY FOR ACCESSING
;               SPECIFICS IN THE HARDWARE
;--------------------------------------------------------

SP_SECTOR:          DC.L        0

MODULE_NAME:            DC.B        'MAIN-SUBCPU',0
MODULE_VERSION:         DC.W        0, 0
MODULE_NEXT:            DC.L        0
MODULE_SIZE:            DC.L        0
MODULE_START_ADDR:      DC.L        $20
MODULE_WORK_ADDR:       DC.L        0

SUB_JUMP_TABLE:         DC.W        SP_INIT-SUB_JUMP_TABLE
                        DC.W        SP_MAIN-SUB_JUMP_TABLE
                        DC.W        SP_IRQ-SUB_JUMP_TABLE
                        DC.W        0

;--------------------------------------------------------
;              INITIALISE THE STACK POINTER
;       THIS WORKS UNDER THE GUISE OF BEING CALLED
;       ON A SINGLE COUROUTINE AFTER THE INITIAL BOOT
;--------------------------------------------------------

SP_INIT:
    RTS

SP_MAIN:
    BNE     SP_MAIN

SP_IRQ:
    RTS