First cut at timer

[fpgaboy.git] / rom.asm

diff --git a/rom.asm b/rom.asm
index 2e98e136fb592519941823a6fa3a865d96b54f0d..93f8524713edd8bb709ba7496a57f76d39295fcb 100644 (file)
--- a/rom.asm
+++ b/rom.asm
@@ -104,13 +104,20 @@ waitsw:
        ld hl,waitswstr
        call puts
        
+       ld c, $07
+       ld a, $07       ;start timer, 4.096KHz
+       ld [c], a
+       
        ld c, $51
        ld a, $00
        ld [c],a
        
+.loop1:
+       push bc
+       call testa
+       pop bc
        ld c, $51
        ld b, $0
-.loop1:
        ld a,[c]
        cp b
        jr z,.loop1
@@ -121,7 +128,24 @@ waitsw:
        ret
 
 waitswstr:
-       db "Diagnostic ROM complete; flip switches to nonzero and then to zero to reset.",$0D,$0A,0
+       db "Diagnostic ROM complete; flip switches to nonzero and then to zero to reset. Expect A.",$0D,$0A,0
+
+testa:
+       ld c, $0F
+       ld a, [c]
+       ld b, $00
+       cp b
+       ret z
+       xor a
+       ld [c], a
+       ld hl, $D000
+       ld c, [hl]
+       inc bc
+       ld [hl], c
+       ld a, c
+       ld c, $50
+       ld [c], a
+       ret
 
 ; Core instruction basic acceptance tests.
 insntest:
@@ -232,14 +256,12 @@ insntest:
 
 ; Serial port manipulation functions.
 putc:
-       push af
        ld b, 0
        ld c, $50
 .waitport:
        ld a,[c]
        cp b
        jr nz,.waitport
-       pop af
        ld [c],a
        ret