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mirror of https://github.com/cc65/cc65.git synced 2024-11-19 21:32:19 +00:00
cc65/libsrc/apple2/crt0.s
uz 8216bf1d6a Force an import of the special symbol __STARTUP__ in the C compiler when
main() is encountered. Define this symbol in the startup code. This will
automatically force linking of the startup code which can then reside inside
the standard library as any other object file.


git-svn-id: svn://svn.cc65.org/cc65/trunk@3988 b7a2c559-68d2-44c3-8de9-860c34a00d81
2009-07-31 12:05:42 +00:00

270 lines
7.3 KiB
ArmAsm

;
; Startup code for cc65 (Apple2 version)
;
.export _exit
.export __STARTUP__ : absolute = 1 ; Mark as startup
.import zerobss
.import initlib, donelib
.import callmain, callirq
.import __RAM_START__ , __RAM_LAST__ ; Linker generated
.import __MOVE_START__, __MOVE_LAST__ ; Linker generated
.import __LC_START__ , __LC_LAST__ ; Linker generated
.import __ZPSAVE_RUN__, __INIT_SIZE__ ; Linker generated
.import __INTERRUPTOR_COUNT__ ; Linker generated
.include "zeropage.inc"
.include "apple2.inc"
.linecont +
; ------------------------------------------------------------------------
.segment "EXEHDR"
.addr __RAM_START__ ; Start address
.word __ZPSAVE_RUN__ - __RAM_START__ + \
__MOVE_LAST__ - __MOVE_START__ ; Size
; ------------------------------------------------------------------------
.segment "STARTUP"
; ProDOS TechRefMan, chapter 5.2.1:
; "For maximum interrupt efficiency, a system program should not
; use more than the upper 3/4 of the stack."
ldx #$FF
txs ; Init stack pointer
; Switch in LC bank 2 for W/O
bit $C081
bit $C081
; Set source start address
lda #<(__ZPSAVE_RUN__ + __INIT_SIZE__)
ldy #>(__ZPSAVE_RUN__ + __INIT_SIZE__)
sta $9B
sty $9C
; Set source last address
lda #<(__ZPSAVE_RUN__ + __INIT_SIZE__ + __LC_LAST__ - __LC_START__)
ldy #>(__ZPSAVE_RUN__ + __INIT_SIZE__ + __LC_LAST__ - __LC_START__)
sta $96
sty $97
; Set destination last address
lda #<__LC_LAST__
ldy #>__LC_LAST__
sta $94
sty $95
; Call into Applesoft Block Transfer Utility - which handles zero
; sized blocks well - to move content of the LC memory area
jsr $D396 ; BLTU + 3
; Set source start address
lda #<__ZPSAVE_RUN__
ldy #>__ZPSAVE_RUN__
sta $9B
sty $9C
; Set source last address
lda #<(__ZPSAVE_RUN__ + __INIT_SIZE__)
ldy #>(__ZPSAVE_RUN__ + __INIT_SIZE__)
sta $96
sty $97
; Set destination last address
lda #<__RAM_LAST__
ldy #>__RAM_LAST__
sta $94
sty $95
; Call into Applesoft Block Transfer Utility - which handles moving
; overlapping blocks upwards well - to move the INIT segment
jsr $D396 ; BLTU + 3
; Delegate all further processing to keep the STARTUP segment small
jsr init
; Avoid re-entrance of donelib. This is also the _exit entry
_exit: ldx #<exit
lda #>exit
jsr reset ; Setup RESET vector
; Switch in ROM in case it wasn't already switched in by a RESET
bit $C082
; Call module destructors
jsr donelib
; Check for valid interrupt vector table entry number
lda intnum
beq exit
; Deallocate interrupt vector table entry
dec params ; Adjust parameter count
jsr $BF00 ; MLI call entry point
.byte $41 ; Dealloc interrupt
.addr params
; Restore the original RESET vector
exit: ldx #$02
: lda rvsave,x
sta SOFTEV,x
dex
bpl :-
; Copy back the zero page stuff
ldx #zpspace-1
: lda zpsave,x
sta sp,x
dex
bpl :-
; ProDOS TechRefMan, chapter 5.2.1:
; "System programs should set the stack pointer to $FF at the
; warm-start entry point."
ldx #$FF
txs ; Re-init stack pointer
; Back to DOS
jmp DOSWARM
; ------------------------------------------------------------------------
.segment "INIT"
; Save the zero page locations we need
init: ldx #zpspace-1
: lda sp,x
sta zpsave,x
dex
bpl :-
; Clear the BSS data
jsr zerobss
; Save the original RESET vector
ldx #$02
: lda SOFTEV,x
sta rvsave,x
dex
bpl :-
; ProDOS TechRefMan, chapter 5.3.5:
; "Your system program should place in the RESET vector the
; address of a routine that ... closes the files."
ldx #<_exit
lda #>_exit
jsr reset ; Setup RESET vector
; Setup the stack
lda HIMEM
sta sp
lda HIMEM+1
sta sp+1 ; Set argument stack ptr
; Check for interruptors
lda #<__INTERRUPTOR_COUNT__
beq :+
; Check for ProDOS
lda $BF00 ; MLI call entry point
cmp #$4C ; Is MLI present? (JMP opcode)
bne prterr
; Allocate interrupt vector table entry
jsr $BF00 ; MLI call entry point
.byte $40 ; Alloc interrupt
.addr params
bcs prterr
; Enable interrupts as old ProDOS versions (i.e. 1.1.1)
; jump to SYS and BIN programs with interrupts disabled
cli
; Call module constructors
: jsr initlib
; Switch in LC bank 2 for R/O
bit $C080
; Push arguments and call main()
jmp callmain
; Print error message and return
prterr: ldx #msglen-1
: lda errmsg,x
jsr $FDED ; COUT
dex
bpl :-
rts
errmsg: .ifdef __APPLE2ENH__
.byte $8D, 't'|$80, 'p'|$80, 'u'|$80, 'r'|$80, 'r'|$80
.byte 'e'|$80, 't'|$80, 'n'|$80, 'i'|$80, ' '|$80, 'c'|$80
.byte 'o'|$80, 'l'|$80, 'l'|$80, 'a'|$80, ' '|$80, 'o'|$80
.byte 't'|$80, ' '|$80, 'd'|$80, 'e'|$80, 'l'|$80, 'i'|$80
.byte 'a'|$80, 'F'|$80, $8D
.else
.byte $8D, 'T'|$80, 'P'|$80, 'U'|$80, 'R'|$80, 'R'|$80
.byte 'E'|$80, 'T'|$80, 'N'|$80, 'I'|$80, ' '|$80, 'C'|$80
.byte 'O'|$80, 'L'|$80, 'L'|$80, 'A'|$80, ' '|$80, 'O'|$80
.byte 'T'|$80, ' '|$80, 'D'|$80, 'E'|$80, 'L'|$80, 'I'|$80
.byte 'A'|$80, 'F'|$80, $8D
.endif
msglen = * - errmsg
; ------------------------------------------------------------------------
.segment "LOWCODE"
; ProDOS TechRefMan, chapter 6.2:
; "Each installed routine must begin with a CLD instruction."
intrpt: cld
; Call interruptors and check for success
jsr callirq
bcc :+
; ProDOS TechRefMan, chapter 6.2:
; "When the routine that can process the interrupt is called, it
; should ... return (via an RTS) with the carry flag clear."
clc
rts
; ProDOS TechRefMan, chapter 6.2:
; "When a routine that cannot process the interrupt is called,
; it should return (via an RTS) with the cary flag set ..."
: sec
rts
; Setup RESET vector
reset: stx SOFTEV
sta SOFTEV+1
eor #$A5
sta PWREDUP
rts
; ------------------------------------------------------------------------
.data
params: .byte $02 ; Parameter count
intnum: .byte $00 ; Interrupt number
.addr intrpt ; Interrupt handler
; ------------------------------------------------------------------------
.segment "ZPSAVE"
zpsave: .res zpspace
; ------------------------------------------------------------------------
.bss
rvsave: .res 3