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cc65/libsrc/atari/crt0.s
cpg 1819b6a38e graphics memory reservation is now done via a contructor; some condes
related changes


git-svn-id: svn://svn.cc65.org/cc65/trunk@543 b7a2c559-68d2-44c3-8de9-860c34a00d81
2000-12-03 23:50:16 +00:00

214 lines
3.3 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
;
.export _exit
.constructor setup_sp,26
.import getargs, argc, argv
.import initlib, donelib
.import zerobss, pushax
.import _main,__filetab,getfd
.import __CODE_LOAD__, __BSS_LOAD__
.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 $FFFF
.word __CODE_LOAD__
.word __BSS_LOAD__ - 1
.code
.reloc
; ------------------------------------------------------------------------
; Actual code
rts ; fix for SpartaDOS / OS/A+
; they first call the entry point from AUTOSTRT and
; then the load addess (this rts here).
; We point AUTOSTRT directly after the rts.
; Real entry point:
; Save the zero page locations we need
ldx #zpspace-1
L1: lda sp,x
sta zpsave,x
dex
bpl L1
; Clear the BSS data
jsr zerobss
; setup the stack
tsx
stx spsave
; report memory usage
lda APPMHI
sta appmsav ; remember old APPMHI value
lda APPMHI+1
sta appmsav+1
lda MEMTOP
sta APPMHI ; initialize our APPMHI value
ldx MEMTOP+1
stx APPMHI+1
; Call module constructors
jsr initlib
; set left margin to 0
lda LMARGN
sta old_lmargin
lda #0
sta LMARGN
; set keyb to upper/lowercase mode
ldx SHFLOK
stx old_shflok
sta SHFLOK
; Initialize conio stuff
lda #$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
; setup sp
setup_sp:
lda APPMHI
sta sp
lda APPMHI+1
sta sp+1
rts
.data
zpsave: .res zpspace
.bss
spsave: .res 1
appmsav: .res 1
old_shflok: .res 1
old_lmargin: .res 1
.segment "AUTOSTRT"
.word $02E0
.word $02E1
.word __CODE_LOAD__ + 1