Cut 1 at an onboard bootloader

[fpgaboy.git] / fpgaboot.asm

diff --git a/fpgaboot.asm b/fpgaboot.asm
index a9236579c3874079fef0f287eb031251fb1383a0..0a714b136deaec0bdd8238be5dbf7cc3d49b8a4f 100644 (file)
--- a/fpgaboot.asm
+++ b/fpgaboot.asm
@@ -1,37 +1,117 @@
        SECTION "boot", HOME[$0]
-       ld a, $AA
+boot:  ld a, $AA
        ld [$FF51], A   ; Poke the LEDs
+
+       ld sp, $FFFE
        
-       ; Write a little bit to the RAM
-       ld H, $01
-       ld L, $00
-       ld A, $00
-       ld [HLI], A
-       ld [HLI], A
-       ld [HLI], A
-       ld [HLI], A
-       ld [HLI], A
-       ld [HLI], A
-       ld [HLI], A
-       ld [HLI], A
+       ld hl, signon
+       call puts
+       
+.wait: ld a, [$FF53]
+       and $02
+       jr z, .nodata
+       ld a, [$FF52]
+       ld [$FF51], a
+       
+       cp $1B          ; Escape
+       jp z, .cbc
+       ld [$FF52], a
+.cbc:  call z, bootcmd
+
+.nodata:       ld a, [$FF51]
+       cp $00
+       jr nz, .wait
+
+doboot:        xor a
+       ld h, a
+       ld l, a
+       ld [hl], $01    ; Select the GB boot rom
        
        ld a, $55
-       ld [$FF51], A   ; Poke the LEDs
+       ld [c], a
        
-       ld A, $FF
-       ld [HLI], A
-       ld [HLI], A
-       ld [HLI], A
-       ld [HLI], A
-       ld [HLI], A
-       ld [HLI], A
-       ld [HLI], A
-       ld [HLI], A
+       ld hl, booting
+       call puts
        
-       ld H, $00
-       ld L, $00
-       ld [HL], $01    ; Select the GB boot rom
        rst $00         ; Boot
+
+signon:
+       db $0D,$0A,$1B,"[1mFPGABoy Boot ROM",$1B,"[0m",$0D,$0A,0
+booting:
+       db "Booting...",$0D,$0A,0
+
+putc:
+       ld c, $53
+       push af
+.waitport:
+       ld a,[c]
+       and $01
+       jr nz,.waitport
+       pop af
+       ld [$FF52],a
+       ret
+
+puts:
+       ld a, [hli]
+       cp $00
+       ret z
+       call putc
+       jr puts
+
+getc:
+       ld a, [$FF53]
+       and $02
+       jr z, getc
+       ld a, [$FF52]
+       ret
+
+bootcmd:
+       call getc
+       cp $56  ;V
+       jr z,.version
+       cp $41  ;A
+       jr z,.addr
+       cp $44  ;D
+       jr z,.data
+       cp $50  ;P
+       jr z,.prog
+       cp $42  ;B
+       jr z,doboot
+       cp $1B
+       jr z,bootcmd    ; If you keep yelling, you're bound to get the thing's attention.
+       ld a, $3f       ;?
+       jr putc
+.version:
+       ld hl, .verstr
+       jr puts
+.verstr:
+       db "V1.00",0
+.addr:
+       call getc
+       ld [$FF60], A
+       call getc
+       ld [$FF61], A
+       call getc
+       ld [$FF62], A
+       ld A, $41       ;A
+       jr putc
+.data:
+       call getc       ; byte count
+       ld c, a
+.dl:   call getc
+       ld [$FF63], A
+       dec c
+       jp nz, .dl
+       ld A, $44       ;D
+       ret
+.prog:
+       ld hl, $FF80
+       ld c, $7F
+.pl:   dec c
+       jp z, $FF80
+       call getc
+       ld [hli], a
+       jr .pl
        
        SECTION "a", HOME[$100]
        nop     ; Make sure we don't overflow.