Startup code with interruptor support by Oliver Schmidt

git-svn-id: svn://svn.cc65.org/cc65/trunk@3479 b7a2c559-68d2-44c3-8de9-860c34a00d81

libsrc/apple2/crt0.s

@@ -5,117 +5,153 @@
 ;
 
         .export		_exit, __Exit
-	.import	   	initlib, donelib
         .import		zerobss
+        .import	   	initlib, donelib
+        .import	   	callmain, callirq
         .import	       	__STARTUP_LOAD__, __BSS_LOAD__	; Linker generated
-	.import		callmain
+        .import	       	__INTERRUPTOR_COUNT__		; Linker generated
 
         .include        "zeropage.inc"
         .include	"apple2.inc"
+        .include	"mli.inc"
 
 ; ------------------------------------------------------------------------
-; The executable header
 
-.segment	"EXEHDR"
+        .segment	"EXEHDR"
 
-       	.word  	__STARTUP_LOAD__                ; Start address
+        .addr		__STARTUP_LOAD__                ; Start address
         .word		__BSS_LOAD__ - __STARTUP_LOAD__	; Size
 
 ; ------------------------------------------------------------------------
-; Place the startup code in a special segment.
 
-.segment       	"STARTUP"
+        .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."
 
+        ; 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
 
-; Save the zero page locations we need
+        ; Delegate all further processing to keep STARTUP small
-
+        jsr	init
-       	ldx	#zpspace-1
-:	lda	sp,x
-   	sta	zpsave,x
-	dex
-       	bpl	:-
-
-; 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
-		
-; Clear the BSS data
-
-	jsr	zerobss
-
-; Setup the stack
-
-	lda    	HIMEM
-	sta	sp
-	lda	HIMEM+1
-       	sta	sp+1   	    	; Set argument stack ptr
-
-; Call module constructors
-
-	jsr	initlib
-
-; Push arguments and call main()
-
-	jsr	callmain
-
-; Avoid re-entrance of donelib. This is also the _exit entry
 
+        ; Avoid re-entrance of donelib. This is also the _exit entry
 _exit:  ldx	#<__Exit
         lda	#>__Exit
         jsr	reset		; Setup RESET vector
 
-; Call module destructors
+        ; Check for valid interrrupt vector table entry number
+        lda	intnum
+        beq	:+
 
-	jsr	donelib
+        ; Deallocate interrupt vector table entry
+        dec	params		; Adjust parameter count
+        jsr	ENTRY
+        .byte	$41		; Dealloc interrupt
+        .addr	params
 
-; Restore the original RESET vector. This is also the __Exit entry
+        ; Call module destructors
+:       jsr	donelib
 
+        ; Restore the original RESET vector. This is also the __Exit entry
 __Exit: ldx	#$02
 :       lda	rvsave,x
         sta	SOFTEV,x
         dex
         bpl	:-
 
-; Copy back the zero page stuff
+        ; Copy back the zero page stuff
-
         ldx	#zpspace-1
 :       lda	zpsave,x
         sta	sp,x
         dex
         bpl	:-
 
-; ProDOS TechRefMan, chapter 5.2.1:
+        ; ProDOS TechRefMan, chapter 5.2.1:
-; "System programs should set the stack pointer to $FF at the warm-start
+        ; "System programs should set the stack pointer to $FF at the
-;  entry point."
+        ;  warm-start entry point."
-
         ldx	#$FF
         txs			; Re-init stack pointer
 
-; Back to DOS
+        ; Back to DOS
-
         jmp	DOSWARM
 
 ; ------------------------------------------------------------------------
-; Setup RESET vector
 
+        .segment       	"INIT"
+
+        ; Save the zero page locations we need
+init:   ldx	#zpspace-1
+:       lda	sp,x
+        sta	zpsave,x
+        dex
+        bpl	:-
+
+        ; 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
+
+        ; Clear the BSS data
+        jsr	zerobss
+
+        ; Setup the stack
+        lda    	HIMEM
+        sta	sp
+        lda	HIMEM+1
+        sta	sp+1   	    	; Set argument stack ptr
+
+        ; Call module constructors
+        jsr	initlib
+
+        ; Check for interruptors
+        lda     #<__INTERRUPTOR_COUNT__
+        beq	:+
+
+        ; Check for ProDOS
+        lda	ENTRY
+        cmp	#$4C		; Is MLI present? (JMP opcode)
+        bne	:+
+
+        ; Allocate interrupt vector table entry
+        jsr	ENTRY
+        .byte	$40		; Alloc interrupt
+        .addr	params
+
+        ; Push arguments and call main()
+:       jmp	callmain
+
+; ------------------------------------------------------------------------
+
+        .segment	"LOWCODE"
+
+        ; ProDOS TechRefMan, chapter 6.2:
+        ; "Each installed routine must begin with a CLD instruction"
+intrpt: cld
+
+        ; Call interruptors
+        jsr	callirq
+
+        ; ProDOS TechRefMan, chapter 6.2:
+        ; "When the routine that can process the interrupt is called, it
+        ;  should ... return (via an RTS) with the carry flag clear."
+        clc
+        rts
+
+; ------------------------------------------------------------------------
+
+        .code
+
+        ; Setup RESET vector
 reset:  stx	SOFTEV
         sta	SOFTEV+1
         eor	#$A5
@@ -123,10 +159,13 @@ reset:	stx	SOFTEV
         rts
 
 ; ------------------------------------------------------------------------
-; Data
 
-.data
+        .data
 
 zpsave: .res	zpspace
 
 rvsave: .res	3
+
+params: .byte	$02		; Parameter count
+intnum: .byte	$00		; Interrupt number
+        .addr	intrpt		; Interrupt handler