don't use constructor to setup runtime stack

[cc65] / libsrc / apple2 / crt0.s

diff --git a/libsrc/apple2/crt0.s b/libsrc/apple2/crt0.s
index ec61770bc23609c4a8309879d3ccbcf09517de45..53b8043ca3f8ae312dbd1afcb71bdefeb309a182 100644 (file)
--- a/libsrc/apple2/crt0.s
+++ b/libsrc/apple2/crt0.s
@@ -1,10 +1,11 @@
 ;
-; Startup code for cc65 (Apple2 version)
+; Oliver Schmidt, 15.09.2009
 ;
-; This must be the *first* file on the linker command line
+; Startup code for cc65 (Apple2 version)
 ;
 
-        .export         _exit
+        .export         _exit, done, return
+        .export         __STARTUP__ : absolute = 1      ; Mark as startup
         .import         zerobss
         .import        initlib, donelib
         .import        callmain, callirq
@@ -40,13 +41,13 @@
        ; 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__)
@@ -68,7 +69,7 @@
        ldy     #>__ZPSAVE_RUN__
        sta     $9B
        sty     $9C
-       
+
        ; Set source last address
        lda     #<(__ZPSAVE_RUN__ + __INIT_SIZE__)
        ldy     #>(__ZPSAVE_RUN__ + __INIT_SIZE__)
@@ -92,7 +93,7 @@
 _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
 
@@ -100,14 +101,14 @@ _exit:  ldx     #<exit
         jsr     donelib
 
         ; Check for valid interrupt vector table entry number
-        lda     intnum
+        lda     int_num
         beq     exit
 
         ; Deallocate interrupt vector table entry
-        dec     params         ; Adjust parameter count
+        dec     i_param                ; Adjust parameter count
         jsr     $BF00          ; MLI call entry point
         .byte   $41            ; Dealloc interrupt
-        .addr   params
+        .addr   i_param
 
         ; Restore the original RESET vector
 exit:   ldx     #$02
@@ -129,8 +130,8 @@ exit:   ldx     #$02
         ldx     #$FF
         txs                     ; Re-init stack pointer
 
-        ; Back to DOS
-        jmp     DOSWARM
+        ; We're done
+        jmp     (done)
 
 ; ------------------------------------------------------------------------
 
@@ -159,26 +160,48 @@ init:   ldx     #zpspace-1
         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 ProDOS
+        ldy     $BF00          ; MLI call entry point
+        cpy     #$4C           ; Is MLI present? (JMP opcode)
+        bne     basic
+        
+        ; Check ProDOS system bit map
+        lda     $BF6F           ; protection for pages $B8 - $BF
+        cmp     #%00000001      ; exactly system global page is protected
+        bne     basic
+
+        ; No BASIC.SYSTEM so quit to ProDOS dispatcher instead
+        lda     #<quit
+        ldx     #>quit
+        sta     done
+        stx     done+1
+        
+        ; No BASIC.SYSTEM so use addr of ProDOS system global page
+        lda     #<$BF00
+        ldx     #>$BF00
+        bne     :+              ; Branch always
+
+        ; Get highest available mem addr from BASIC interpreter
+basic:  lda     HIMEM
+        ldx     HIMEM+1
+
+        ; Setup the C stack
+:       sta     sp
+        stx     sp+1
 
         ; Check for interruptors
         lda     #<__INTERRUPTOR_COUNT__
         beq     :+
 
         ; Check for ProDOS
-        lda     $BF00          ; MLI call entry point
-        cmp     #$4C           ; Is MLI present? (JMP opcode)
+        cpy     #$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
+        .addr   i_param
         bcs     prterr
 
        ; Enable interrupts as old ProDOS versions (i.e. 1.1.1)
@@ -224,7 +247,7 @@ msglen = * - errmsg
 
         ; ProDOS TechRefMan, chapter 6.2:
         ; "Each installed routine must begin with a CLD instruction."
-intrpt: cld
+intptr: cld
 
         ; Call interruptors and check for success
         jsr     callirq
@@ -247,15 +270,35 @@ reset:  stx     SOFTEV
         sta     SOFTEV+1
         eor     #$A5
         sta     PWREDUP
-        rts
+return: rts
+
+        ; Quit to ProDOS dispatcher
+quit:   jsr     $BF00           ; MLI call entry point
+        .byte   $65             ; Quit
+        .word   q_param
 
+; ------------------------------------------------------------------------
+
+        .rodata
+
+        ; MLI parameter list for quit        
+q_param:.byte   $04            ; param_count
+        .byte   $00            ; quit_type
+        .word   $0000          ; reserved
+        .byte   $00            ; reserved
+        .word   $0000          ; reserved
+       
 ; ------------------------------------------------------------------------
 
         .data
 
-params: .byte   $02            ; Parameter count
-intnum: .byte   $00            ; Interrupt number
-        .addr   intrpt         ; Interrupt handler
+        ; MLI parameter list for (de)alloc interrupt
+i_param:.byte   $02            ; param_count
+int_num:.byte   $00            ; int_num
+        .addr   intptr         ; int_code
+
+        ; Location to jump to when we're done
+done:   .addr   DOSWARM
 
 ; ------------------------------------------------------------------------