mirror of
https://github.com/cc65/cc65.git
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277 lines
4.9 KiB
ArmAsm
277 lines
4.9 KiB
ArmAsm
;
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; Startup code for cc65 (ATARI version)
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;
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; Contributing authors:
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; Mark Keates
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; Freddy Offenga
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; Christian Groessler
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;
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; This must be the *first* file on the linker command line
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;
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.export _exit
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.import getargs, argc, argv
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.import __hinit, initconio, zerobss, pushax, doatexit
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.import _main,__filetab,getfd
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.import __CODE_LOAD__, __BSS_LOAD__
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.import __graphmode_used
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.include "atari.inc"
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; ------------------------------------------------------------------------
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; Define and export the ZP variables for the runtime
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.exportzp sp, sreg, regsave
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.exportzp ptr1, ptr2, ptr3, ptr4
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.exportzp tmp1, tmp2, tmp3, tmp4
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.exportzp fntemp, regbank, zpspace
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sp = $D2 ; (2bytes) stack pointer
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sreg = $D4 ; (2bytes) secondary register/high 16 bit for longs
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regsave = $D6 ; (4bytes) slot to save/restore (E)AX into
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ptr1 = $DA ; (2bytes)
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ptr2 = $DC ; (2bytes)
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ptr3 = $DE ; (2bytes)
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ptr4 = $E0 ; (2bytes)
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tmp1 = $E2 ; (1byte)
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tmp2 = $E3 ; (1byte)
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tmp3 = $E4 ; (1byte)
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tmp4 = $E5 ; (1byte)
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fntemp = $E6 ; (2bytes) pointer to file name
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regbank = $E8 ; (6bytes) 6 byte register bank
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zpspace = $EE - sp ; Zero page space allocated
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; ------------------------------------------------------------------------
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; EXE header
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.segment "EXEHDR"
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.word $FFFF
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.word __CODE_LOAD__
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.word __BSS_LOAD__ - 1
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.code
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.reloc
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; ------------------------------------------------------------------------
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; Actual code
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rts ; fix for SpartaDOS / OS/A+
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; they first call the entry point from AUTOSTRT and
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; then the load addess (this rts here).
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; We point AUTOSTRT directly after the rts.
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; Real entry point:
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; Save the zero page locations we need
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ldy #zpspace-1
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L1: lda sp,y
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sta zpsave,y
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dey
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bpl L1
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; Clear the BSS data
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jsr zerobss
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; setup the stack
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tsx
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stx spsave
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; report memory usage and initialize stack pointer
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lda APPMHI
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sta appmsav
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lda APPMHI+1
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sta appmsav+1
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jsr getmemtop ; adjust for graphics mode to use
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sta sp
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sta APPMHI
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stx sp+1 ; Set argument stack ptr
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stx APPMHI+1
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; set left margin to 0
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lda LMARGN
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sta old_lmargin
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lda #0
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sta LMARGN
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; set keyb to upper/lowercase mode
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ldx SHFLOK
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stx old_shflok
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sta SHFLOK
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; Initialize the heap
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jsr __hinit
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; Initialize conio stuff
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jsr initconio
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lda #$FF
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sta CH
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; set stdio stream handles
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lda #0
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jsr getfd
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sta __filetab ; setup stdin
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lda #0
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jsr getfd
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sta __filetab + 2 ; setup stdout
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lda #0
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jsr getfd
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sta __filetab + 4 ; setup stderr
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; Pass command line if present
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jsr getargs
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lda argc
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ldx argc+1
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jsr pushax ; argc
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lda #<argv
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ldx #>argv
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jsr pushax ; argv
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ldy #4 ; Argument size
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jsr _main ; call the users code
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; fall thru to exit...
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_exit: jsr doatexit ; call exit functions
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ldx spsave
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txs ; Restore stack pointer
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; restore left margin
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lda old_lmargin
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sta LMARGN
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; restore kb mode
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lda old_shflok
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sta SHFLOK
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; restore APPMHI
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lda appmsav
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sta APPMHI
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lda appmsav+1
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sta APPMHI+1
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; Copy back the zero page stuff
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ldy #zpspace-1
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L2: lda zpsave,y
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sta sp,y
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dey
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bpl L2
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; Back to DOS
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rts
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; *** end of main startup code
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; calc. upper memory limit to use
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.proc getmemtop
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ldy __graphmode_used
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beq ignore ; mode 0 doesn't need adjustment
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cpy #32
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bcs ignore ; invalid value
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tya
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asl a
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tay
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lda MEMTOP
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sec
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sbc grmemusage,y
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pha
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lda MEMTOP+1
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sbc grmemusage+1,y
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tax
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pla
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rts
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ignore: lda MEMTOP
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ldx MEMTOP+1
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rts
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.endproc
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.data
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zpsave: .res zpspace
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; memory usage of the different graphics modes (0-31)
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; values < 0 of "bytes needed" are mappped to 0
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; bytes needed ; mode ; val. of MEMTOP
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grmemusage:
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.word 0 ; 0 ; 39967
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.word 0 ;-318 ; 1 ; 40285
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.word 0 ;-568 ; 2 ; 40535
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.word 0 ;-558 ; 3 ; 40525
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.word 0 ;-298 ; 4 ; 40265
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.word 182 ; 5 ; 39785
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.word 1182 ; 6 ; 38785
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.word 3198 ; 7 ; 36769
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.word 7120 ; 8 ; 32847
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.word 7146 ; 9 ; 32821
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.word 7146 ; 10 ; 32821
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.word 7146 ; 11 ; 32821
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.word 162 ; 12 ; 39805
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.word 0 ;-328 ; 13 ; 40295
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.word 3278 ; 14 ; 36689
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.word 7120 ; 15 ; 32847
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.word 0 ; 16 ; 39967
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.word 0 ;-320 ; 17 ; 40287
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.word 0 ;-572 ; 18 ; 40539
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.word 0 ;-560 ; 19 ; 40527
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.word 0 ;-296 ; 20 ; 40263
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.word 184 ; 21 ; 39783
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.word 1192 ; 22 ; 38775
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.word 3208 ; 23 ; 36759
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.word 7146 ; 24 ; 32821
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.word 7146 ; 25 ; 32821
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.word 7146 ; 26 ; 32821
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.word 7146 ; 27 ; 32821
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.word 160 ; 28 ; 39807
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.word 0 ;-332 ; 29 ; 40299
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.word 3304 ; 30 ; 36663
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.word 7146 ; 31 ; 32821
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; the program used to get these values (Atari BASIC):
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; 100 FILE=0
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; 110 IF FILE=1 THEN OPEN #1,8,0,"D:FREEMEM.OUT"
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; 120 IF FILE<>1 THEN OPEN #1,8,0,"E:"
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; 200 DIM G(32)
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; 210 FOR I=0 TO 32:GRAPHICS I:GOSUB 1000:G(I)=VAL:NEXT I
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; 220 GRAPHICS 0
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; 230 FOR I=0 TO 31:PRINT #1;I;":",G(I);" - ";G(0)-G(I):NEXT I
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; 240 CLOSE #1
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; 999 END
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; 1000 VAL=PEEK(741)+256*PEEK(742)
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; 1010 RETURN
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.bss
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spsave: .res 1
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appmsav: .res 1
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old_shflok: .res 1
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old_lmargin: .res 1
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.segment "AUTOSTRT"
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.word $02E0
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.word $02E1
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.word __CODE_LOAD__ + 1
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