;
; Startup code for cc65 (C16 version)
;
-; Note: The C16 is actually the Plus/4 with just 16KB of memory. So many
-; things are similar here, and we even use the plus4.inc include file.
+; Note: The C16 is actually the Plus/4 with just 16KB of memory. So, many
+; things are similar here; and, we even use the plus4.inc include file.
;
- .export _exit
+ .export _exit
.export __STARTUP__ : absolute = 1 ; Mark as startup
- .import initlib, donelib, callirq
- .import callmain, zerobss
+ .import initlib, donelib
+ .import callmain, zerobss
.import MEMTOP, RESTOR, BSOUT, CLRCH
- .import __INTERRUPTOR_COUNT__
+ .importzp ST
.include "zeropage.inc"
- .include "plus4.inc"
-
-
-; ------------------------------------------------------------------------
-; Place the startup code in a special segment.
-
-.segment "STARTUP"
-
-; BASIC header with a SYS call
-
- .word Head ; Load address
-Head: .word @Next
- .word .version ; Line number
- .byte $9E,"4109" ; SYS 4109
- .byte $00 ; End of BASIC line
-@Next: .word 0 ; BASIC end marker
+ .include "plus4.inc"
; ------------------------------------------------------------------------
-; Actual code
-
- ldx #zpspace-1
-L1: lda sp,x
- sta zpsave,x ; save the zero page locations we need
- dex
- bpl L1
-
-; Close open files
+; Startup code
- jsr CLRCH
+.segment "STARTUP"
-; Switch to second charset
+Start:
- lda #14
- jsr BSOUT
+; Save the zero-page locations that we need.
-; Clear the BSS data
+ ldx #zpspace-1
+L1: lda sp,x
+ sta zpsave,x
+ dex
+ bpl L1
- jsr zerobss
+; Switch to the second charset.
-; Save system stuff and setup the stack
+ lda #14
+ jsr BSOUT
- tsx
- stx spsave ; save system stk ptr
+; Clear the BSS data.
- sec
- jsr MEMTOP ; Get top memory
- cpy #$80 ; We can only use the low 32K :-(
- bcc MemOk
- ldy #$80
- ldx #$00
-MemOk: stx sp
- sty sp+1 ; set argument stack ptr
+ jsr zerobss
-; If we have IRQ functions, chain our stub into the IRQ vector
+; Save some system stuff; and, set up the stack.
- 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
+ tsx
+ stx spsave ; save system stk ptr
-; Call module constructors
+ sec
+ jsr MEMTOP ; Get top memory
+ cpy #$80 ; We can only use the low 32K :-(
+ bcc MemOk
+ ldy #$80
+ ldx #$00
+MemOk: stx sp
+ sty sp+1 ; set argument stack ptr
-NoIRQ1: jsr initlib
+; Call the module constructors.
-; Push arguments and call main()
+ jsr initlib
- jsr callmain
+; Push the command-line arguments; and, call main().
-; Call module destructors. This is also the _exit entry.
+ jsr callmain
-_exit: pha ; Save the return code on stack
- jsr donelib ; Run module destructors
+; Call the module destructors. This is also the exit() entry.
-; Reset the IRQ vector if we chained it.
+_exit: pha ; Save the return code on stack
+ jsr donelib ; Run module destructors
- 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.
-; Copy back the zero page stuff
+ ldx #zpspace-1
+L2: lda zpsave,x
+ sta sp,x
+ dex
+ bpl L2
-NoIRQ2: ldx #zpspace-1
-L2: lda zpsave,x
- sta sp,x
- dex
- bpl L2
+; Store the return code into BASIC's status variable.
-; Store the return code into ST
+ pla
+ sta ST
- pla
- sta ST
+; Restore the stack pointer.
-; Restore the stack pointer
+ ldx spsave
+ txs
- ldx spsave
- txs
+; Back to BASIC.
-; Reset changed vectors
-
- 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
+ rts
; ------------------------------------------------------------------------
-; Data
-.data
+.segment "INIT"
-IRQInd: jmp $0000
+zpsave: .res zpspace
-.segment "ZPSAVE"
-
-zpsave: .res zpspace
+; ------------------------------------------------------------------------
.bss
-spsave: .res 1
-
-
+spsave: .res 1
projects / cc65 / blobdiff