cleanups and add more comments

[cc65] / libsrc / c128 / cgetc.s

diff --git a/libsrc/c128/cgetc.s b/libsrc/c128/cgetc.s
index 391a25fd2dfbb66b215f7d0fdbd16fd02dfb9e1e..46f13d197c18214c54e4429d7f3a19d19cb428d0 100644 (file)
--- a/libsrc/c128/cgetc.s
+++ b/libsrc/c128/cgetc.s
@@ -4,28 +4,69 @@
 ; char cgetc (void);
 ;
 
-       .export         _cgetc
-       .import         cursor
+        .export         _cgetc
+        .constructor    initcgetc
+        .destructor     donecgetc
 
-       .include        "c128.inc"
+        .import         cursor
 
-_cgetc:        lda     KEY_COUNT       ; Get number of characters
-       bne     L2              ; Jump if there are already chars waiting
+        .include        "c128.inc"
 
-; Switch on the cursor if needed
+;--------------------------------------------------------------------------
 
-       lda     cursor
-               beq     L1
-       jsr     CURS_ON
-       jmp     L2
-L1:            lda     #$01
-       jsr     CURS_OFF
-L2:            lda     KEY_COUNT       ; Check characters again
-       beq     L2
-       jsr     CURS_OFF        ; Switch cursor off, if characters available
+_cgetc: lda     KEY_COUNT       ; Get number of characters
+        bne     L2              ; Jump if there are already chars waiting
+
+; Switch on the cursor if needed. We MUST always switch the cursor on, 
+; before switching it off, because switching it off will restore the 
+; character attribute remembered when it was switched on. So just switching
+; it off will restore the wrong character attribute.
+
+        jsr     CURS_SET        ; Set cursor to current position
+        jsr     CURS_ON
+        lda     cursor
+        bne     L1
+        lda     #$01
+        jsr     CURS_OFF
+L1:     lda     KEY_COUNT       ; Check characters again
+        beq     L1
+        jsr     CURS_OFF        ; Switch cursor off, if characters available
+
+L2:     jsr     KBDREAD         ; Read char and return in A
+        ldx     #0
+        rts
+
+;--------------------------------------------------------------------------
+; Module constructor/destructor
+
+.bss
+keyvec: .res    2
+
+.segment        "INIT"
+initcgetc:
+
+; Save the old vector
+
+        lda     KeyStoreVec
+        sta     keyvec
+        lda     KeyStoreVec+1
+        sta     keyvec+1
+
+; Set the new vector. I can only hope that this works for other C128
+; versions...
+
+        lda     #<$C6B7
+        ldx     #>$C6B7
+        jmp     SetVec
+
+.code
+donecgetc:
+        lda     keyvec
+        ldx     keyvec+1
+SetVec: sei
+        sta     KeyStoreVec
+        stx     KeyStoreVec+1
+        cli
+        rts
 
-               jsr     KBDREAD         ; Read char and return in A
-       ldx     #0
-       rts
 
-