+ SECTION "a",HOME
+main:
+ ld c, $51
+ ld a, $FF
+ ld [c],a
+ ld sp,$DFFF
+
+ ld hl,text
+ call puts
+
+ call memtest
+ call waitsw
+ jp main
+
+text:
+ db $1B,"[1mFPGABoy Diagnostic ROM",$1B,"[0m",$0D,$0A,0
+
+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
+
+ ld hl, $C000
+.rd:
+ ld a,h
+ xor l
+ ld b,a
+ ld a, [hli]
+ cp b
+ jp nz, .memfail
+
+ ld a, $DF
+ cp h
+ jp nz, .rd
+ ld a, $80
+ cp l
+ jp nz, .rd
+
+ 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
+
+ ld c, $51
+ ld a, $00
+ ld [c],a
+
+ 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
+
+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
+
git.joshuawise.com / fpgaboy.git / commitdiff