fix comments

[cc65] / libsrc / vic20 / crt0.s

diff --git a/libsrc/vic20/crt0.s b/libsrc/vic20/crt0.s
index 72d5799af9478e43aa7a2e5ae4110e98dc42771f..559f22dff3180b81c8bd95d9ef6e02279f6f41c8 100644 (file)
--- a/libsrc/vic20/crt0.s
+++ b/libsrc/vic20/crt0.s
@@ -1,19 +1,18 @@
 ;
 ; Startup code for cc65 (Vic20 version)
-;
-; This must be the *first* file on the linker command line
 ;
 
        .export         _exit
-       .import         initlib, donelib
+        .export         __STARTUP__ : absolute = 1      ; Mark as startup
+       .import         initlib, donelib, callirq
                .import         zerobss, push0
        .import         callmain
         .import         RESTOR, BSOUT, CLRCH
+       .import         __INTERRUPTOR_COUNT__
        .import         __RAM_START__, __RAM_SIZE__     ; Linker generated
 
         .include        "zeropage.inc"
        .include        "vic20.inc"
-       .include        "../cbm/cbm.inc"
 
 ; ------------------------------------------------------------------------
 ; Place the startup code in a special segment.
@@ -26,18 +25,17 @@
 Head:   .word   @Next
         .word   .version        ; Line number
         .byte   $9E             ; SYS token
-        .byte   <(((@Start / 1000) .mod 10) + $30)
-        .byte   <(((@Start /  100) .mod 10) + $30)
-        .byte   <(((@Start /   10) .mod 10) + $30)
-        .byte   <(((@Start /    1) .mod 10) + $30)
+        .byte   <(((Start / 1000) .mod 10) + $30)
+        .byte   <(((Start /  100) .mod 10) + $30)
+        .byte   <(((Start /   10) .mod 10) + $30)
+        .byte   <(((Start /    1) .mod 10) + $30)
         .byte   $00             ; End of BASIC line
 @Next:  .word   0               ; BASIC end marker
-@Start:
 
 ; ------------------------------------------------------------------------
 ; Actual code
 
-       ldx     #zpspace-1
+Start:  ldx            #zpspace-1
 L1:    lda     sp,x
        sta     zpsave,x        ; Save the zero page locations we need
        dex
@@ -66,41 +64,85 @@ L1: lda     sp,x
        lda     #>(__RAM_START__ + __RAM_SIZE__)
                sta     sp+1            ; Set argument stack ptr
 
+; If we have IRQ functions, chain our stub into the IRQ vector
+
+        lda     #<__INTERRUPTOR_COUNT__
+       beq     NoIRQ1
+       lda     IRQVec
+               ldx     IRQVec+1
+       sta     IRQInd+1
+       stx     IRQInd+2
+       lda     #<IRQStub
+       ldx     #>IRQStub
+       sei
+       sta     IRQVec
+       stx     IRQVec+1
+       cli
+
 ; Call module constructors
 
-       jsr     initlib
+NoIRQ1: jsr     initlib
 
 ; Push arguments and call main()
 
-               jsr     callmain
+        jsr     callmain
 
-; Call module destructors. This is also the _exit entry.
+; Back from main (This is also the _exit entry). Run module destructors
 
-_exit: jsr     donelib         ; Run module destructors
+_exit:  jsr     donelib
 
-; Restore system stuff
+; Reset the IRQ vector if we chained it.
 
-       ldx     spsave
-       txs                     ; Restore stack pointer
+        pha                    ; Save the return code on stack
+       lda     #<__INTERRUPTOR_COUNT__
+       beq     NoIRQ2
+       lda     IRQInd+1
+       ldx     IRQInd+2
+       sei
+       sta     IRQVec
+       stx     IRQVec+1
+       cli
 
 ; Copy back the zero page stuff
 
-               ldx     #zpspace-1
+NoIRQ2: ldx    #zpspace-1
 L2:    lda     zpsave,x
        sta     sp,x
        dex
                bpl     L2
 
+; Place the program return code into ST
+
+       pla
+       sta     ST
+
+; Restore the stack pointer
+
+       ldx     spsave
+       txs
+
 ; Reset changed vectors, back to basic
 
        jmp     RESTOR
 
 
+; ------------------------------------------------------------------------
+; The IRQ vector jumps here, if condes routines are defined with type 2.
+
+IRQStub:
+       cld                             ; Just to be sure
+               jsr     callirq                 ; Call the functions
+               jmp     IRQInd                  ; Jump to the saved IRQ vector
+
 ; ------------------------------------------------------------------------
 ; Data
 
 .data
 
+IRQInd: jmp     $0000
+
+.segment        "ZPSAVE"
+
 zpsave:        .res    zpspace
 
 .bss