It works, but why?

[fpgaboy.git] / rom.asm

diff --git a/rom.asm b/rom.asm
index 2ede41c0c23e6b115968356ab14b79f401877d6e..6989b2d5d53252f1b7e3345b87a1e60165801276 100644 (file)
--- a/rom.asm
+++ b/rom.asm
@@ -1,139 +1,71 @@
        SECTION "a",HOME
+
 main:
-       ld c, $51
+       ld c, $51       ; Note that we are alive.
        ld a, $FF
        ld [c],a
-       ld sp,$DFFF
-
-       ld hl,text
-       call puts
        
-       call memtest
-       call waitsw
-       jp main
+       ld sp, $DFF0
+       
+;      ld hl, $DF81
+;      ld a, $80
+;      ld [hl], a
 
-text:
-       db $1B,"[1mFPGABoy Diagnostic ROM",$1B,"[0m",$0D,$0A,0
+;      ld c, $07
+;      ld a, $07       ;start timer, 4.096KHz
+;      ld [c], a
+;diqs: ei
+;      ld a, $80
+;      ld c, $51
+;      ld [c], a
+;      jr diqs
+       call irqhand
+coqs: jr coqs
 
-memtest:
-       ld hl,memteststr
-       call puts
-       
-       ld hl, $C000
-.wr:
-       ld a,h
-       xor l
-       ld [hli],a
-       ld a, $DF
-       cp h
-       jp nz, .wr
-       ld a, $80
-       cp l
-       jp nz, .wr
+       section "Diq", HOME[$38]
+fuqed:
+       di
+       jr fuqed
 
-       ld hl, $C000
-.rd:
-       ld a,h
-       xor l
-       ld b,a
-       ld a, [hli]
-       cp b
-       jp nz, .memfail
+       section "fuq",HOME[$100]
+irqhand:
+       PUSH AF
+       PUSH BC
+       PUSH DE
+       PUSH HL
        
-       ld a, $DF
-       cp h
-       jp nz, .rd
-       ld a, $80
-       cp l
-       jp nz, .rd
+;      ld c, $51
+;      ld a, $F0
+;      ld [c], a
        
-       ld hl, testokstr
-       call puts
-       ret
-.memfail:
-       @ decrement hl the easy way
-       ld a,[hld]
-       push hl
-       ld hl, failatstr
-       call puts
-       pop hl
-       ld a, h
-       call puthex
-       ld a, l
-       call puthex
-       ld a, $0A
-       call putc
-       ld a, $0D
-       call putc
-       ret
-
-memteststr:
-       db "Testing memory from $C000 to $DF80...",0
-testokstr:
-       db " OK!",$0D,$0A,0
-failatstr:
-       db " Test failed at $",0
-puthex:
-       push af
-       rra
-       rra
-       rra
-       rra
-       ld b,$0F
-       and b
-       ld b,$30
-       add b
-       call putc
-       pop af
-       ld b,$0F
-       and b
-       ld b,$30
-       add b
-       call putc
-       ret
-
-waitsw:
-       ld hl,waitswstr
-       call puts
+       xor a
+       ld c, $0F       ; ack the irq
+       ld [c], a
        
-       ld c, $51
-       ld a, $00
-       ld [c],a
+       ;ld a, $41      ; print A
+       ;call putc
        
-       ld c, $51
-       ld b, $0
-.loop1:
-       ld a,[c]
-       cp b
-       jp z,.loop1
-.loop2:
-       ld a,[c]
-       cp b
-       jp nz,.loop2
-       ret
-
-waitswstr:
-       db "Diagnostic ROM complete; flip switches to nonzero and then to zero to reset.",$0D,$0A,0
+;      ld hl, $DF81
+;      ld a, [hl]
+;      ld b, 1
+;      add b
+       ld a, $08
+       ld hl, $FF51
+;      ld c, $51
+       nop
+       nop
+       ld [hl], a
 
-putc:
-       push af
-       ld b, 0
-       ld c, $50
-.waitport:
-       ld a,[c]
-       cp b
-       jp nz,.waitport
-       pop af
-       ld [c],a
-       ret
-
-puts:
-       ld a, [hli]
-       ld b, $00
-       cp b
-       jp z, .done
-       call putc
-       jp puts
-.done:
-       ret
 
+;      ld c, $51
+;      ld a, $0F
+;      ld [c], a
+       
+       POP HL
+       POP DE
+       POP BC
+       POP AF
+       RETI
+       db $18,$FE,$18,$FE,$18,$FE,$18,$FE,$18,$FE,$18,$FE,$18,$FE,$18,$FE
+       db $18,$FE,$18,$FE,$18,$FE,$18,$FE,$18,$FE,$18,$FE,$18,$FE,$18,$FE
+       db $18,$FE,$18,$FE,$18,$FE,$18,$FE,$18,$FE,$18,$FE,$18,$FE,$18,$FE