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mirror of https://github.com/cc65/cc65.git synced 2024-11-02 03:04:31 +00:00
cc65/libsrc/atari/crt0.s
cuz 99ecc9a609 Removed initialization code to set the screen size and replaced it by a
separate module that contains a module constructor. In some cases, the
code was even unnecessary, since the screen size is known in advance.


git-svn-id: svn://svn.cc65.org/cc65/trunk@476 b7a2c559-68d2-44c3-8de9-860c34a00d81
2000-11-23 19:05:32 +00:00

311 lines
5.4 KiB
ArmAsm

;
; Startup code for cc65 (ATARI version)
;
; Contributing authors:
; Mark Keates
; Freddy Offenga
; Christian Groessler
;
; This must be the *first* file on the linker command line
;
RESERVE_MOUSE_MEMORY = 1 ; for P/M
.ifdef RESERVE_MOUSE_MEMORY
.export mouse_pm0
.endif
.export _exit
.import getargs, argc, argv
.import initlib, donelib
.import zerobss, pushax
.import _main,__filetab,getfd
.import __CODE_LOAD__, __BSS_LOAD__
.import __graphmode_used
.include "atari.inc"
; ------------------------------------------------------------------------
; Define and export the ZP variables for the runtime
.exportzp sp, sreg, regsave
.exportzp ptr1, ptr2, ptr3, ptr4
.exportzp tmp1, tmp2, tmp3, tmp4
.exportzp fntemp, regbank, zpspace
.zeropage
zpstart = *
sp: .res 2 ; Stack pointer
sreg: .res 2 ; Secondary register/high 16 bit for longs
regsave: .res 2 ; slot to save/restore (E)AX into
ptr1: .res 2
ptr2: .res 2
ptr3: .res 2
ptr4: .res 2
tmp1: .res 1
tmp2: .res 1
tmp3: .res 1
tmp4: .res 1
fntemp: .res 2 ; Pointer to file name
regbank: .res 6 ; 6 byte register bank
zpspace = * - zpstart ; Zero page space allocated
.code
; ------------------------------------------------------------------------
; EXE header
.segment "EXEHDR"
.word $FFFF
.word __CODE_LOAD__
.word __BSS_LOAD__ - 1
.code
.reloc
; ------------------------------------------------------------------------
; Actual code
rts ; fix for SpartaDOS / OS/A+
; they first call the entry point from AUTOSTRT and
; then the load addess (this rts here).
; We point AUTOSTRT directly after the rts.
; Real entry point:
; Save the zero page locations we need
ldx #zpspace-1
L1: lda sp,x
sta zpsave,x
dex
bpl L1
; Clear the BSS data
jsr zerobss
; setup the stack
tsx
stx spsave
; report memory usage and initialize stack pointer
lda APPMHI
sta appmsav
lda APPMHI+1
sta appmsav+1
jsr getmemtop ; adjust for graphics mode to use
sta sp
sta APPMHI
stx sp+1 ; Set argument stack ptr
stx APPMHI+1
; set left margin to 0
lda LMARGN
sta old_lmargin
lda #0
sta LMARGN
; set keyb to upper/lowercase mode
ldx SHFLOK
stx old_shflok
sta SHFLOK
; Call module constructors
jsr initlib
; Initialize conio stuff
lda #$FF
sta CH
; set stdio stream handles
lda #0
jsr getfd
sta __filetab ; setup stdin
lda #0
jsr getfd
sta __filetab + 2 ; setup stdout
lda #0
jsr getfd
sta __filetab + 4 ; setup stderr
; Pass command line if present
jsr getargs
lda argc
ldx argc+1
jsr pushax ; argc
lda #<argv
ldx #>argv
jsr pushax ; argv
ldy #4 ; Argument size
jsr _main ; call the users code
; Call module destructors. This is also the _exit entry.
_exit: jsr donelib ; Run module destructors
; Restore system stuff
ldx spsave
txs ; Restore stack pointer
; restore left margin
lda old_lmargin
sta LMARGN
; restore kb mode
lda old_shflok
sta SHFLOK
; restore APPMHI
lda appmsav
sta APPMHI
lda appmsav+1
sta APPMHI+1
; Copy back the zero page stuff
ldx #zpspace-1
L2: lda zpsave,x
sta sp,x
dex
bpl L2
; Back to DOS
rts
; *** 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
.ifdef RESERVE_MOUSE_MEMORY
adj_mouse:
txa ; get upper byte of address
and #%11111000 ; make 2k aligned
sec
sbc #%00001000 ; reserve 2k
tax
adc #3 ; add 4 (C = 1)
sta mouse_pm0
lda #0
.endif
rts
ignore: lda MEMTOP
ldx MEMTOP+1
.ifdef RESERVE_MOUSE_MEMORY
bne adj_mouse
.else
rts
.endif
.endproc
.data
zpsave: .res zpspace
.rodata
; 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
old_shflok: .res 1
old_lmargin: .res 1
.ifdef RESERVE_MOUSE_MEMORY
mouse_pm0: .res 1
.endif
.segment "AUTOSTRT"
.word $02E0
.word $02E1
.word __CODE_LOAD__ + 1