atari5200: implement bgcolor() and textcolor()

Includes some other small fixes/cleanups.
2019-04-02 21:11:11 +02:00
parent edd596b2a4
commit ec5e38617a
18 changed files with 261 additions and 26 deletions
--- a/libsrc/atari5200/textcolor.s
+++ b/libsrc/atari5200/textcolor.s
@@ -0,0 +1,28 @@
+;
+; Christian Groessler, 02-Apr-2019
+;
+; unsigned char __fastcall__ textcolor (unsigned char color);
+
+        .export         _textcolor
+        .import         conio_color
+
+        .include        "atari.inc"
+
+
+_textcolor:
+        ; move bits #0 and #1 to bits #6 and #7
+        and     #3
+        clc
+        ror     a
+        ror     a
+        ror     a               ; new conio_color value
+        ldx     conio_color     ; get old value
+        sta     conio_color     ; store new value
+        txa
+        ; move bits #6 and #7 to bits #0 and #1
+        clc
+        rol     a
+        rol     a
+        rol     a
+        ldx     #0
+        rts