Optimized mul20 & mul40 and extracted to new library.

2019-03-21 15:59:45 +01:00
parent fbf302e6cd
commit 399250a105
14 changed files with 216 additions and 92 deletions
--- a/libsrc/atari5200/cputc.s
+++ b/libsrc/atari5200/cputc.s
@@ -10,7 +10,7 @@

        .export         _cputcxy, _cputc
        .export         plot, cputdirect, putchar
-        .import         gotoxy, mul20
+        .import         gotoxy, _mul20
        .importzp       ptr4
        .import         setcursor

@@ -75,8 +75,7 @@ putchar:
        pha                     ; save char

        lda     ROWCRS_5200
-        jsr     mul20           ; destroys tmp4
-        clc
+        jsr     _mul20          ; destroys tmp4, carry is cleared
        adc     SAVMSC          ; add start of screen memory
        sta     ptr4
        txa
--- a/libsrc/atari5200/mul20.s
+++ b/libsrc/atari5200/mul20.s
@@ -1,33 +0,0 @@
-;
-; Christian Groessler, April 2014
-;
-; mul20
-; multiplies A by 20 and returns result in AX
-; uses tmp4
-
-        .importzp       tmp4
-        .export         mul20,loc_tmp
-
-.proc   mul20
-
-        ldx     #0
-        stx     tmp4
-        sta     loc_tmp
-        asl     a
-        rol     tmp4
-        asl     a
-        rol     tmp4            ; val * 4
-        adc     loc_tmp
-        bcc     L1
-        inc     tmp4            ; val * 5
-L1:     asl     a
-        rol     tmp4            ; val * 10
-        asl     a
-        rol     tmp4            ; val * 20
-        ldx     tmp4
-        rts
-
-.endproc
-
-        .bss
-loc_tmp:.res    1