Replaced $30 by literal '0' for better readability.

[cc65] / libsrc / plus4 / crt0.s

diff --git a/libsrc/plus4/crt0.s b/libsrc/plus4/crt0.s
index 07b3631c0ab44b5f4b490c1842c1423b582f4329..f9e79db78675c3fafb46c04d27f9decc7e13038c 100644 (file)
--- a/libsrc/plus4/crt0.s
+++ b/libsrc/plus4/crt0.s
@@ -1,15 +1,14 @@
 ;
 ; Startup code for cc65 (Plus/4 version)
-;
-; This must be the *first* file on the linker command line
 ;
 
        .export         _exit
         .export         brk_jmp
+        .export         __STARTUP__ : absolute = 1      ; Mark as startup
 
-       .import         condes, initlib, donelib
-       .import         push0, callmain, zerobss
-       .import         __IRQFUNC_TABLE__, __IRQFUNC_COUNT__
+       .import         callirq_y, initlib, donelib
+       .import         callmain, zerobss
+       .import         __INTERRUPTOR_COUNT__
 
         .include        "zeropage.inc"
        .include        "plus4.inc"
@@ -21,35 +20,40 @@
 IRQInd                 = $500  ; JMP $0000 - used as indirect IRQ vector
 
 ; ------------------------------------------------------------------------
-; Place the startup code in a special segment to cope with the quirks of
-; plus/4 banking.
+; BASIC header with a SYS call
 
-.segment               "STARTUP"
+.segment               "EXEHDR"
 
         .word   Head            ; Load address
 Head:   .word   @Next
         .word   .version        ; Line number
-        .byte   $9E,"4109"     ; SYS 4109
+        .byte   $9E             ; SYS token
+        .byte   <(((Start / 1000) .mod 10) + '0')
+        .byte   <(((Start /  100) .mod 10) + '0')
+        .byte   <(((Start /   10) .mod 10) + '0')
+        .byte   <(((Start /    1) .mod 10) + '0')
         .byte   $00             ; End of BASIC line
 @Next:  .word   0               ; BASIC end marker
 
 ; ------------------------------------------------------------------------
-; Actual code
+; Startup code
+
+.segment               "STARTUP"
+
+Start:
+
+; Save the zero page locations we need
 
         sei                     ; No interrupts since we're banking out the ROM
         sta     ENABLE_RAM
                ldx     #zpspace-1
 L1:    lda     sp,x
-       sta     zpsave,x        ; save the zero page locations we need
+       sta     zpsave,x
        dex
                bpl     L1
         sta     ENABLE_ROM
         cli
 
-; Close open files
-
-       jsr     $FFCC           ; CLRCH
-
 ; Switch to second charset
 
        lda     #14
@@ -59,7 +63,7 @@ L1:   lda     sp,x
 ; usable RAM.
 
                tsx
-               stx     spsave          ; save system stk ptr
+               stx     spsave          ; save system stk ptr
 
         lda     #<$FD00
         sta     sp
@@ -80,31 +84,29 @@ L1: lda     sp,x
 
        jsr     zerobss
 
-; Call module constructors
-
-       jsr     initlib
-
 ; Initialize irqcount, which means that from now own custom linked in IRQ
 ; handlers (via condes) will be called.
 
-        lda     #.lobyte(__IRQFUNC_COUNT__*2)
+        lda     #.lobyte(__INTERRUPTOR_COUNT__*2)
         sta     irqcount
 
+; Call module constructors
+
+       jsr     initlib
+
 ; Push arguments and call main()
 
        jsr     callmain
 
 ; Back from main (this is also the _exit entry). Run module destructors.
 
-_exit:         pha                     ; Save the return code
-       lda     #0
-        sta     irqcount        ; Disable custom IRQ handlers
+_exit:         pha                     ; Save the return code
         jsr    donelib         ; Run module destructors
 
-; Restore system stuff
+; Disable chained IRQ handlers
 
-               ldx     spsave
-               txs
+       lda     #0
+        sta     irqcount        ; Disable custom IRQ handlers
 
 ; Copy back the zero page stuff
 
@@ -119,6 +121,11 @@ L2:        lda     zpsave,x
        pla
        sta     ST
 
+; Restore the stack pointer
+
+               ldx     spsave
+               txs
+
 ; Enable the ROM, reset changed vectors and return to BASIC
 
         sta     ENABLE_ROM
@@ -147,15 +154,13 @@ IRQ:    cld                       ; Just to be sure
         bne     dobreak
 
 ; It's an IRQ and RAM is enabled. If we have handlers, call them. We will use
-; a flag here instead of loading __IRQFUNC_COUNT__ directly, since the condes
-; function is not reentrant. The irqcount flag will be set/reset from the main
-; code, to avoid races.
+; a flag here instead of loading __INTERRUPTOR_COUNT__ directly, since the
+; condes function is not reentrant. The irqcount flag will be set/reset from
+; the main code, to avoid races.
 
        ldy     irqcount
        beq     @L1
-               lda     #<__IRQFUNC_TABLE__
-       ldx     #>__IRQFUNC_TABLE__
-       jsr     condes                  ; Call the IRQ functions
+        jsr     callirq_y       ; Call the IRQ functions
 
 ; Since the ROM handler will end with an RTI, we have to fake an IRQ return
 ; on stack, so we get control of the CPU after the ROM handler and can switch
@@ -165,10 +170,10 @@ IRQ:    cld                       ; Just to be sure
         pha
         lda     #<irq_ret
         pha
-               php                     ; Push faked IRQ frame on stack
-       pha                     ; Push faked A register
-       pha                     ; Push faked X register
-       pha                     ; Push faked Y register
+               php                     ; Push faked IRQ frame on stack
+       pha                     ; Push faked A register
+       pha                     ; Push faked X register
+       pha                     ; Push faked Y register
         sta     ENABLE_ROM      ; Switch to ROM
         jmp     (IRQVec)        ; Jump indirect to kernal irq handler
 
@@ -196,13 +201,16 @@ nohandler:
 ; Data
 
 .data
-zpsave:                .res    zpspace
 
 ; BRK handling
 brk_jmp:        jmp     $0000
 
 spsave:                .res    1
 
-.bss
 irqcount:       .byte   0
 
+.segment        "ZPSAVE"
+
+zpsave:                .res    zpspace
+
+