Added size checking code contributed by Marco van den Heuvel.

git-svn-id: svn://svn.cc65.org/cc65/trunk@4566 b7a2c559-68d2-44c3-8de9-860c34a00d81

diff --git a/libsrc/c64/c64-vdc.s b/libsrc/c64/c64-vdc.s
index 5f3d9d9a723c06d1f0e3216ec241551a614d51b5..be1626b1eb649c18cb3674f3af374f6e1a0df409 100644 (file)
--- a/libsrc/c64/c64-vdc.s
+++ b/libsrc/c64/c64-vdc.s
@@ -3,6 +3,10 @@
 ; (based on code by Ullrich von Bassewitz)
 ; Maciej 'YTM/Elysium' Witkowiak <ytm@elysium.pl>
 ; 06,20.12.2002
+;
+; VDC test added by
+; Marco van den Heuvel, 2010-01-22
+;
 
        .include        "zeropage.inc"
 
@@ -67,35 +71,49 @@ window:             .res    256                ; memory window
 ;
 
 INSTALL:
-       ; do test for VDC presence here???
-
-       ldx     #VDC_CSET       ; determine size of RAM...
-       jsr     vdcgetreg
-       sta     tmp1
-       ora     #%00010000
-       jsr     vdcputreg       ; turn on 64k
-
-       jsr     settestadr1     ; save original value of test byte
-       jsr     vdcgetbyte
-       sta     tmp2
-
-       lda     #$55            ; write $55 here
-       ldy     #ptr1
-       jsr     test64k         ; read it here and there
-       lda     #$aa            ; write $aa here
-       ldy     #ptr2
-       jsr     test64k         ; read it here and there
+        ldx     #0
+        ldy     #0
+               lda     #VDC_CSET       ; determine size of RAM...
+               sta     VDC_ADDR_REG
+
+@L0:    bit     VDC_ADDR_REG
+        bmi     @present
+        inx
+        bne     @L0
+        iny
+        bne     @L0
+       lda     #<EM_ERR_NO_DEVICE
+       ldx     #>EM_ERR_NO_DEVICE
+       rts
 
-       jsr     settestadr1
-       lda     tmp2
-       jsr     vdcputbyte      ; restore original value of test byte
-
-       lda     ptr1            ; do bytes match?
-       cmp     ptr1+1
-       bne     @have64k
-       lda     ptr2
-       cmp     ptr2+1
-       bne     @have64k
+@present:
+       ldx     #VDC_CSET       ; determine size of RAM...
+       jsr     vdcgetreg
+       sta     tmp1
+       ora     #%00010000
+       jsr     vdcputreg       ; turn on 64k
+
+       jsr     settestadr1     ; save original value of test byte
+       jsr     vdcgetbyte
+       sta     tmp2
+
+       lda     #$55            ; write $55 here
+       ldy     #ptr1
+       jsr     test64k         ; read it here and there
+       lda     #$aa            ; write $aa here
+       ldy     #ptr2
+       jsr     test64k         ; read it here and there
+
+       jsr     settestadr1
+       lda     tmp2
+       jsr     vdcputbyte      ; restore original value of test byte
+
+       lda     ptr1            ; do bytes match?
+       cmp     ptr1+1
+       bne     @have64k
+       lda     ptr2
+       cmp     ptr2+1
+       bne     @have64k
 
        ldx     #VDC_CSET
        lda     tmp1