;
-; Startup code for cc65 (PCEngine version)
+; Start-up code for cc65 (PC-Engine version)
;
-; by Groepaz/Hitmen <groepaz@gmx.net>
+; by Groepaz/Hitmen <groepaz@gmx.net>,
; based on code by Ullrich von Bassewitz <uz@cc65.org>
;
-; This must be the *first* file on the linker command line
+; 2018-02-24, Greg King
;
.export _exit
- .export __STARTUP__ : absolute = 1 ; Mark as startup
+ .export __STARTUP__ : absolute = 1 ; Mark as start-up
.import initlib, donelib
- .import push0, _main, zerobss
- .import initheap
- .import IRQStub
-
- ; Linker generated
- .import __RAM_START__, __RAM_SIZE__
- .import __ROM0_START__, __ROM0_SIZE__
- .import __ROM_START__, __ROM_SIZE__
- .import __STARTUP_LOAD__,__STARTUP_RUN__, __STARTUP_SIZE__
- .import __CODE_LOAD__,__CODE_RUN__, __CODE_SIZE__
- .import __RODATA_LOAD__,__RODATA_RUN__, __RODATA_SIZE__
- .import __DATA_LOAD__,__DATA_RUN__, __DATA_SIZE__
- .import __BSS_SIZE__
+ .import push0, _main
+ .import IRQStub, __nmi
+ .importzp sp
+
+ ; Linker-generated
+ .import __CARTSIZE__
+ .import __DATA_LOAD__, __DATA_RUN__, __DATA_SIZE__
+ .import __BSS_RUN__, __BSS_SIZE__
+ .import __MAIN_START__, __MAIN_SIZE__, __STACKSIZE__
.include "pce.inc"
.include "extzp.inc"
- .importzp sp
- .importzp ptr1,ptr2
- .importzp tmp1,tmp2,tmp3
-
; ------------------------------------------------------------------------
-; Place the startup code in a special segment.
-
- .segment "STARTUP"
-
-start:
-
- ; setup the CPU and System-IRQ
+; Place the start-up code in a special segment.
- ; Initialize CPU
+.segment "STARTUP"
- sei
+ ; Initialize the CPU.
+start: sei
nop
- csh ; set high speed CPU mode
- nop
- cld
+ csh ; Set high-speed CPU mode
nop
- ; Setup stack and memory mapping
+ ; Set up the stack and the memory mapping.
ldx #$FF ; Stack top ($21FF)
txs
- ; at startup all MPRs are set to 0, so init them
- lda #$ff
- tam #%00000001 ; 0000-1FFF = Hardware page
+ ; At power-on, most MPRs have random values; so, initiate them.
+ lda #$FF
+ tam #%00000001 ; $0000-$1FFF = Hardware bank
lda #$F8
- tam #%00000010 ; 2000-3FFF = Work RAM
-
- ; FIXME: setup a larger block of memory to use with C-code
+ tam #%00000010 ; $2000-$3FFF = Work RAM
;lda #$F7
- ;tam #%00000100 ; 4000-5FFF = Save RAM
- ;lda #1
- ;tam #%00001000 ; 6000-7FFF Page 2
- ;lda #2
- ;tam #%00010000 ; 8000-9FFF Page 3
- ;lda #3
- ;tam #%00100000 ; A000-BFFF Page 4
+ ;tam #%00000100 ; $4000-$47FF = 2K Battery-backed RAM
;lda #4
- ;tam #%01000000 ; C000-DFFF Page 5
- ;lda #0
- ;tam #%10000000 ; e000-fFFF hucard/syscard bank 0
-
- ; Clear work RAM (2000-3FFF)
- stz <$00
- tii $2000, $2001, $1FFF
-
- ; Initialize hardware
+ ;tam #%00001000 ; $6000-$7FFF
+
+ lda #$01
+ ldx #>$8000
+ cpx #>__CARTSIZE__
+ bcc @L1 ;(blt)
+ tam #%00010000 ; $8000-$9FFF = ROM bank 1 (32K block of ROM)
+ inc a
+ tam #%00100000 ; $A000-$BFFF = ROM bank 2
+ inc a
+@L1: tam #%01000000 ; $C000-$DFFF = ROM bank 3 (32K) or 1 (16K)
+ ;lda #$00 ; (The reset default)
+ ;tam #%10000000 ; $E000-$FFFF Hucard/Syscard bank 0
+
+ ; Initialize the hardware.
stz TIMER_CTRL ; Timer off
- lda #$07
+ lda #%00000111
sta IRQ_MASK ; Interrupts off
- stz IRQ_STATUS ; Acknowledge timer
- ; FIXME; i dont know why the heck this one doesnt work when called from a constructor :/
+ ; FIXME; I don't know why the heck this one doesn't work when called from a constructor. -Groepaz :-/
+.if 0 ; It now seems to work (at least, in Mednafen). -Greg King
.import vdc_init
jsr vdc_init
+.endif
- ; Turn on background and VD interrupt/IRQ1
- lda #$05
- sta IRQ_MASK ; IRQ1=on
-
- ; Clear the BSS data
- jsr zerobss
+ ; Allow interrupts from the VDC.
+ lda #%00000101
+ sta IRQ_MASK ; IRQ1 = on
; Copy the .data segment to RAM
tii __DATA_LOAD__, __DATA_RUN__, __DATA_SIZE__
- ; setup the stack
- lda #<(__RAM_START__+__RAM_SIZE__)
+ ; Clear the .bss segment
+ stz __BSS_RUN__
+ tii __BSS_RUN__, __BSS_RUN__ + 1, __BSS_SIZE__ - 1
+
+ ; Set up the stack
+ lda #<(__MAIN_START__ + __MAIN_SIZE__ + __STACKSIZE__)
+ ldx #>(__MAIN_START__ + __MAIN_SIZE__ + __STACKSIZE__)
sta sp
- lda #>(__RAM_START__+__RAM_SIZE__)
- sta sp + 1
+ stx sp+1
- ; Call module constructors
+ ; Call the module constructors.
jsr initlib
- cli ; allow IRQ only after constructors have run
+ stz IRQ_STATUS ; Clear IRQs
+ cli ; Allow IRQ only after constructors have run
; Pass an empty command line
jsr push0 ; argc
jsr push0 ; argv
ldy #4 ; Argument size
- jsr _main ; call the users code
+ jsr _main ; Call the user's code
- ; Call module destructors. This is also the _exit entry.
-_exit:
- jsr donelib ; Run module destructors
+ ; Call the module destructors. This is also the exit() entry.
+_exit: jsr donelib
- ; reset the PCEngine (start over)
+ ; Reset the PCEngine (start over).
jmp start
-_nmi:
- rti
-
.export initmainargs
initmainargs:
rts
; ------------------------------------------------------------------------
; hardware vectors
; ------------------------------------------------------------------------
- .segment "VECTORS"
+.segment "VECTORS"
- .word IRQStub ; $fff6 IRQ2 (External IRQ, BRK)
- .word IRQStub ; $fff8 IRQ1 (VDC)
- .word IRQStub ; $fffa Timer
- .word _nmi ; $fffc NMI
- .word start ; $fffe reset
+ .word IRQStub ; $FFF6 IRQ2 (External IRQ, BRK)
+ .word IRQStub ; $FFF8 IRQ1 (VDC)
+ .word IRQStub ; $FFFA Timer
+ .word __nmi ; $FFFC NMI
+ .word start ; $FFFE reset
projects / cc65 / blobdiff