;
.export __STARTUP__ : absolute = 1 ; Mark as startup
- .export _exit, start
+ .export _exit, start, excexit, SP_save
.import initlib, donelib
.import callmain, zerobss
.import __RESERVED_MEMORY__
- .import __RAM_START__, __RAM_SIZE__
+ .import __MAIN_START__, __MAIN_SIZE__
+ .import __LOWCODE_RUN__, __LOWCODE_SIZE__
.ifdef __ATARIXL__
.import __STACKSIZE__
.import sram_init
.segment "STARTUP"
rts ; fix for SpartaDOS / OS/A+
- ; they first call the entry point from AUTOSTRT and
- ; then the load addess (this rts here).
+ ; They first call the entry point from AUTOSTRT; and
+ ; then, the load address (this rts here).
; We point AUTOSTRT directly after the rts.
; Real entry point:
jsr sram_init
.endif
-; Clear the BSS data
+; Clear the BSS data.
jsr zerobss
-; Setup the stack
+; Set up the stack.
tsx
stx SP_save
-.ifndef __ATARIXL__
+.ifdef __ATARIXL__
+
+ lda #<(__MAIN_START__ + __MAIN_SIZE__ + __STACKSIZE__)
+ ldx #>(__MAIN_START__ + __MAIN_SIZE__ + __STACKSIZE__)
+ sta sp
+ stx sp+1
-; Report memory usage
+.else
+
+; Report the memory usage.
lda APPMHI
+ ldx APPMHI+1
sta APPMHI_save ; remember old APPMHI value
- lda APPMHI+1
- sta APPMHI_save+1
+ stx APPMHI_save+1
sec
lda MEMTOP
sbc #<__RESERVED_MEMORY__
sta APPMHI ; initialize our APPMHI value
- sta sp ; setup runtime stack part 1
+ sta sp ; set up runtime stack part 1
lda MEMTOP+1
sbc #>__RESERVED_MEMORY__
sta APPMHI+1
- sta sp+1 ; setup runtime stack part 2
-
-.else
-
- lda #<(__RAM_START__ + __RAM_SIZE__ + __STACKSIZE__)
- sta sp
- lda #>(__RAM_START__ + __RAM_SIZE__ + __STACKSIZE__)
- sta sp+1
+ sta sp+1 ; set up runtime stack part 2
.endif
-; Call module constructors
+; Call the module constructors.
jsr initlib
-; Set left margin to 0
+; Set the left margin to 0.
lda LMARGN
sta LMARGN_save
ldy #0
sty LMARGN
-; Set keyb to upper/lowercase mode
+; Set the keyboard to upper-/lower-case mode.
ldx SHFLOK
stx SHFLOK_save
sty SHFLOK
-; Initialize conio stuff
+; Initialize the conio stuff.
dey ; Set Y to $FF
sty CH ; remove keypress which might be in the input buffer
-; Push arguments and call main
+; Push the command-line arguments; and, call main().
jsr callmain
-; Call module destructors. This is also the _exit entry.
+; Call the module destructors. This is also the exit() entry.
-_exit: jsr donelib ; Run module destructors
+_exit: ldx SP_save
+ txs ; Restore stack pointer
-; Restore system stuff
+; Restore the system stuff.
- ldx SP_save
- txs ; Restore stack pointer
+excexit:jsr donelib ; Run module destructors; 'excexit' is called from the exec routine
-; Restore left margin
+; Restore the left margin.
lda LMARGN_save
sta LMARGN
-; Restore kb mode
+; Restore the kb mode.
lda SHFLOK_save
sta SHFLOK
-; Restore APPMHI
+; Restore APPMHI.
lda APPMHI_save
+ ldx APPMHI_save+1
sta APPMHI
- lda APPMHI_save+1
- sta APPMHI+1
+ stx APPMHI+1
.ifdef __ATARIXL__
lda RAMTOP_save
sta RAMTOP
lda MEMTOP_save
+ ldx MEMTOP_save+1
sta MEMTOP
- lda MEMTOP_save+1
- sta MEMTOP+1
+ stx MEMTOP+1
-; Issue a GRAPHICS 0 call (copied'n'pasted from TGI drivers) in
-; order to restore screen memory to its defailt location just
+; Issue a GRAPHICS 0 call (copied'n'pasted from the TGI drivers), in
+; order to restore screen memory to its default location just
; before the ROM.
jsr findfreeiocb
lda #0
sta ICBLH,x
jsr CIOV_org
-; No error checking here, shouldn't happen(tm), and no way to
+; No error checking here, shouldn't happen(TM); and, no way to
; recover anyway.
lda #CLOSE
.endif
-; Turn on cursor
+; Turn on the cursor.
ldx #0
stx CRSINH
-; Back to DOS
+; Back to DOS.
rts
.ifndef __ATARIXL__
APPMHI_save: .res 2
.endif
+
+; ------------------------------------------------------------------------
+
+.segment "LOWCODE" ; have at least one (empty) segment of LOWCODE, so that the next line works even if the program doesn't make use of this segment
+.assert (__LOWCODE_RUN__ + __LOWCODE_SIZE__ <= $4000 || __LOWCODE_RUN__ > $7FFF || __LOWCODE_SIZE__ = 0), warning, "'lowcode area' reaches into $4000..$7FFF bank memory window"
+; check for LOWBSS_SIZE = 0 not needed since the only file which uses LOWBSS (irq.s) also uses LOWCODE
+; check for LOWCODE_RUN > $7FFF is mostly for cartridges, where this segment is loaded high (into cart ROM)
+; there is a small chance that if the user loads the program really high, LOWCODE is above $7FFF, but LOWBSS is below -- no warning emitted in this case
projects / cc65 / blobdiff