Update the 7seg more often.

[fpgaboy.git] / rom.asm

diff --git a/rom.asm b/rom.asm
index 640c2b075bbef77b911785ad8a678c6385c255f8..cd3cf2daf4600afb79201fde195e3e413909c73d 100644 (file)
--- a/rom.asm
+++ b/rom.asm
@@ -1,57 +1,64 @@
        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
+       ld sp, $DFFF
+
+       ld hl, signon
        call puts
        
        call memtest
+
+       call insntest
+
        call waitsw
-       jp main
 
-text:
+       jr main
+
+signon:
        db $0D,$0A,$1B,"[1mFPGABoy Diagnostic ROM",$1B,"[0m",$0D,$0A,0
 
+; Memory tester: writes h ^ l to all addresses from C000 to DF80.
 memtest:
        ld hl,memteststr
        call puts
        
-       ld hl, $C000
+       ld hl, $C000            ; Write loop
 .wr:
        ld a,h
        xor l
        ld [hli],a
        ld a, $DF
        cp h
-       jp nz, .wr
+       jr nz, .wr
        ld a, $80
        cp l
-       jp nz, .wr
+       jr nz, .wr
 
-       ld hl, $C000
+       ld hl, $C000            ; Read loop
 .rd:
        ld a,h
        xor l
        ld b,a
        ld a, [hli]
        cp b
-       jp nz, .memfail
+       jr nz, .memfail
        
        ld a, $DF
        cp h
-       jp nz, .rd
+       jr nz, .rd
        ld a, $80
        cp l
-       jp nz, .rd
+       jr nz, .rd
        
-       ld hl, testokstr
+       ld hl, testokstr        ; Say we're OK
        call puts
        ret
-.memfail:
-       @ decrement hl the easy way
+.memfail:                      ; Say we failed (sadface)
+       ; decrement hl the easy way
        ld a,[hld]
        push hl
        ld hl, failatstr
@@ -66,14 +73,14 @@ memtest:
        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:
+
+puthex:                                ; Put two hex nibbles to the serial console.
        push af
        rra
        rra
@@ -92,6 +99,7 @@ puthex:
        call putc
        ret
 
+; Wait for switches to be flipped on and off again.
 waitsw:
        ld hl,waitswstr
        call puts
@@ -105,16 +113,106 @@ waitsw:
 .loop1:
        ld a,[c]
        cp b
-       jp z,.loop1
+       jr z,.loop1
 .loop2:
        ld a,[c]
        cp b
-       jp nz,.loop2
+       jr nz,.loop2
        ret
 
 waitswstr:
        db "Diagnostic ROM complete; flip switches to nonzero and then to zero to reset.",$0D,$0A,0
 
+; Core instruction basic acceptance tests.
+insntest:
+       ld hl, .insnteststr
+       call puts
+       
+       ; Test PUSH and POP.
+       ld b, $12
+       ld c, $34
+       ld d, $56
+       ld e, $78
+       push bc
+       pop de
+       ld hl, .pushpopfail
+       ld a, d
+       cp b
+       jr nz,.fail
+       ld a, e
+       cp c
+       jr nz,.fail
+       
+       ; Test ALU (HL).
+       ld hl, .ff
+       ld a, $FF
+       xor [hl]
+       ld hl, .xorhlfail
+       jr nz, .fail
+       
+       ; Test JP (HL)
+       ld hl, .jphl
+       jp [hl]
+       ld hl, .jphlfail
+       jr .fail
+       rst $00
+.jphl:
+
+       ; Test JR
+       ld a, $FF
+       ld b, $00
+       cp b
+       jr nz,.jr
+       ld hl, .jrfail
+       jr .fail
+       rst $00
+.jr:
+       
+       ; Test CP.
+       ld hl, .cpfail
+       ld a, $10
+       ld b, $20
+       cp b
+       jr nc,.fail
+       ld a, $20
+       ld b, $10
+       cp b
+       jr c,.fail
+       
+       ; Test CPL
+       ld hl, .cplfail
+       ld a, $55
+       ld b, $AA
+       cpl
+       cp b
+       jr nz,.fail
+       
+       ld hl, .ok
+       call puts
+       ret
+.fail:
+       call puts
+       ret
+.insnteststr:
+       db "Testing instructions... ",$0
+.pushpopfail:
+       db "PUSH/POP test failed.",$0D,$0A,0
+.ff:
+       db $FF
+.xorhlfail:
+       db "XOR [HL] test failed.",$0D,$0A,0
+.jphlfail:
+       db "JP [HL] test failed.",$0D,$0A,0
+.jrfail:
+       db "JR test failed.",$0D,$0A,0
+.cpfail:
+       db "CP test failed.",$0D,$0A,0
+.cplfail:
+       db "CPL test failed.",$0D,$0A,0
+.ok:
+       db "OK!",$0D,$0A,0
+
+; Serial port manipulation functions.
 putc:
        push af
        ld b, 0
@@ -122,7 +220,7 @@ putc:
 .waitport:
        ld a,[c]
        cp b
-       jp nz,.waitport
+       jr nz,.waitport
        pop af
        ld [c],a
        ret
@@ -131,9 +229,9 @@ puts:
        ld a, [hli]
        ld b, $00
        cp b
-       jp z, .done
+       jr z, .done
        call putc
-       jp puts
+       jr puts
 .done:
        ret