cbm stuff from greggs pull request

2017-12-11 19:49:14 +01:00
parent 947b09ad96
commit 8902730756
21 changed files with 936 additions and 7 deletions
--- a/libsrc/c128/cpeekc.s
+++ b/libsrc/c128/cpeekc.s
@@ -0,0 +1,65 @@
+;
+; 2016-02-28, Groepaz
+; 2017-06-26, Greg King
+;
+; char cpeekc (void);
+;
+
+        .export         _cpeekc
+
+        .import         plot, popa
+
+        .include        "zeropage.inc"
+        .include        "c128.inc"
+
+
+_cpeekc:
+        lda     MODE
+        bmi     @c80
+
+        ldy     CURS_X
+        lda     (SCREEN_PTR),y  ; get char
+
+@return:
+        and     #<~$80          ; remove reverse flag
+
+; Convert the screen code into a PetSCII code.
+; $00 - $1F: +$40
+; $20 - $3F
+; $40 - $7F: +$80
+
+        cmp     #$20
+        bcs     @sk1            ;(bge)
+        ora     #$40
+        rts
+
+@sk1:   cmp     #$40
+        bcc     @end            ;(blt)
+        ora     #$80
+@end:   ldx     #0
+        rts
+
+@c80:
+        lda     SCREEN_PTR
+        ldy     SCREEN_PTR+1
+        clc
+        adc     CURS_X
+        bcc     @s
+        iny
+
+        ; get byte from VDC mem
+@s:     ldx     #VDC_DATA_LO
+        stx     VDC_INDEX
+@L0:    bit     VDC_INDEX
+        bpl     @L0
+        sta     VDC_DATA
+        dex
+        stx     VDC_INDEX
+        sty     VDC_DATA
+
+        ldx     #VDC_RAM_RW
+        stx     VDC_INDEX
+@L1:    bit     VDC_INDEX
+        bpl     @L1             ; wait for blanking
+        lda     VDC_DATA
+        jmp     @return