Subversion Repositories NedoOS

        OUTPUT "build/loader6128.bin"

code_start      equ $8000
        org code_start

start:
        ld a,$FF        ; OFF
        call $BC6B      ; CASNOISY

        ; check loading screen
        ld a,(settings.load_screen)
        or a
        jr z,.load_pages

.load_screen:
        ; load screen
        ld hl,$C000     ; dest
        ld de,$4000     ; size
        ld a,$16        ; type: data
        call $BCA1      ; CASREAD (headerless)

.load_pages:
        ld hl,page_table
        ld a,(hl) : inc hl      ; read entry count
        or a
        jr z,.load_code

.loop_pages:
        push af

        ld a,(hl) : inc hl      ; page num
        or %11000000            ; mask to set bank 1: page n (eg: page at $4000)
        ld b,$74
        ld c,a

        di 
        out (c),c       ; mmr -> page in 'n' at $C000

        ld c,(hl) : inc hl      ; offset from base int bc
        ld b,(hl) : inc hl
        ld e,(hl) : inc hl      ; len into de
        ld d,(hl) : inc hl
        push hl

        ld hl,$4000     ; base
        add hl,bc       ; hl contains target addr

        ; load the page
        ld a,$16        ; type: data
        call $BCA1      ; CASREAD (headerless)

        ld bc,$74C0
        out (c),c       ; put mmr back to normal
        pop hl

        ei
        
        pop af

        dec a
        jr nz,.loop_pages

.load_code:
        ld hl,(settings.start_addr)
        push hl

        ld hl,(settings.code_addr)
        ld de,(settings.code_len)
        ld a,$16        ; type: data
        jp $BCA1        ; CASREAD

settings:
.load_screen:   .db $00
.start_addr:    .dw $0000
.code_addr:             .dw $0000
.code_len:              .dw $0000
page_table:
.num:                           .db $00 ; how many pages to load?
.data:  
        ; .db num
        ; .dw start
        ; .dw len