adapt reserved memory with _graphmode_used variable (user settable)

git-svn-id: svn://svn.cc65.org/cc65/trunk@124 b7a2c559-68d2-44c3-8de9-860c34a00d81

diff --git a/libsrc/atari/crt0.s b/libsrc/atari/crt0.s
index 66222d2489a55e72bbb51b8b885a32003da44936..92fea420aff709fe9c7c2e1fdfe195c2e77766ac 100644 (file)
--- a/libsrc/atari/crt0.s
+++ b/libsrc/atari/crt0.s
@@ -14,6 +14,7 @@
        .import         __hinit, initconio, zerobss, pushax, doatexit
        .import         _main,__filetab,getfd
        .import         __CODE_LOAD__, __BSS_LOAD__
+       .import         __graphmode_used
 
        .include        "atari.inc"
 
@@ -83,13 +84,13 @@ L1: lda     sp,y
        sta     appmsav
        lda     APPMHI+1
        sta     appmsav+1
+
+       jsr     getmemtop       ; adjust for graphics mode to use
        
-       lda     #<$8000
        sta     sp
        sta     APPMHI
-       lda     #>$8000
-       sta     sp+1            ; Set argument stack ptr
-       sta     APPMHI+1
+       stx     sp+1            ; Set argument stack ptr
+       stx     APPMHI+1
        
 ; set left margin to 0
 
@@ -177,11 +178,92 @@ L2:       lda     zpsave,y
 
        rts
 
-.data
+; *** end of main startup code
+
+
+; calc. upper memory limit to use
+
+.proc  getmemtop
+
+       ldy     __graphmode_used
+       beq     ignore          ; mode 0 doesn't need adjustment
+       cpy     #32
+       bcs     ignore          ; invalid value
+
+       tya
+       asl     a
+       tay
+       lda     MEMTOP
+       sec
+       sbc     grmemusage,y
+       pha
+       lda     MEMTOP+1
+       sbc     grmemusage+1,y
+       tax
+       pla
+       rts
+
+ignore:        lda     MEMTOP
+       ldx     MEMTOP+1
+       rts
+
+.endproc
+
+       .data
 
 zpsave:        .res    zpspace
-       
-.bss
+
+; memory usage of the different graphics modes (0-31)
+; values < 0 of "bytes needed" are mappped to 0
+;               bytes needed    ; mode ; val. of MEMTOP
+grmemusage:
+       .word   0               ; 0     ; 39967
+       .word   0 ;-318         ; 1     ; 40285
+       .word   0 ;-568         ; 2     ; 40535
+       .word   0 ;-558         ; 3     ; 40525
+       .word   0 ;-298         ; 4     ; 40265
+       .word   182             ; 5     ; 39785
+       .word   1182            ; 6     ; 38785
+       .word   3198            ; 7     ; 36769
+       .word   7120            ; 8     ; 32847
+       .word   7146            ; 9     ; 32821
+       .word   7146            ; 10    ; 32821
+       .word   7146            ; 11    ; 32821
+       .word   162             ; 12    ; 39805
+       .word   0 ;-328         ; 13    ; 40295
+       .word   3278            ; 14    ; 36689
+       .word   7120            ; 15    ; 32847
+       .word   0               ; 16    ; 39967
+       .word   0 ;-320         ; 17    ; 40287
+       .word   0 ;-572         ; 18    ; 40539
+       .word   0 ;-560         ; 19    ; 40527
+       .word   0 ;-296         ; 20    ; 40263
+       .word   184             ; 21    ; 39783
+       .word   1192            ; 22    ; 38775
+       .word   3208            ; 23    ; 36759
+       .word   7146            ; 24    ; 32821
+       .word   7146            ; 25    ; 32821
+       .word   7146            ; 26    ; 32821
+       .word   7146            ; 27    ; 32821
+       .word   160             ; 28    ; 39807
+       .word   0 ;-332         ; 29    ; 40299
+       .word   3304            ; 30    ; 36663
+       .word   7146            ; 31    ; 32821
+
+; the program used to get these values (Atari BASIC):
+;  100 FILE=0
+;  110 IF FILE=1 THEN OPEN #1,8,0,"D:FREEMEM.OUT"
+;  120 IF FILE<>1 THEN OPEN #1,8,0,"E:"
+;  200 DIM G(32)
+;  210 FOR I=0 TO 32:GRAPHICS I:GOSUB 1000:G(I)=VAL:NEXT I
+;  220 GRAPHICS 0
+;  230 FOR I=0 TO 31:PRINT #1;I;":",G(I);" - ";G(0)-G(I):NEXT I
+;  240 CLOSE #1
+;  999 END 
+;  1000 VAL=PEEK(741)+256*PEEK(742)
+;  1010 RETURN 
+
+       .bss
 
 spsave:                .res    1
 appmsav:       .res    1