; 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
+; 2018-02-11, Greg King
;
.export _exit
.export __STARTUP__ : absolute = 1 ; Mark as startup
.import initlib, donelib
- .import push0, _main, zerobss
- .import initheap
- .import tmp1,tmp2,tmp3
-
- ; 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
+
+ ; 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
; ------------------------------------------------------------------------
; Place the startup code in a special segment.
start:
- ; setup the CPU and System-IRQ
+ ; Set up the CPU and System-IRQ
; Initialize CPU
-
sei
nop
- csh ; set high speed CPU mode
- nop
- cld
+ csh ; Set high speed CPU mode
nop
- ; Setup stack and memory mapping
+ ; Set up stack and 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
+ ;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 hardware
- stz TIMER_COUNT ; Timer off
+ stz TIMER_CTRL ; Timer off
lda #$07
sta IRQ_MASK ; Interrupts off
stz IRQ_STATUS ; Acknowledge timer
lda #$05
sta IRQ_MASK ; IRQ1=on
- ; Clear the BSS data
- jsr zerobss
-
; Copy the .data segment to RAM
- lda #<(__DATA_LOAD__)
- sta ptr1
- lda #>(__DATA_LOAD__)
- sta ptr1+1
- lda #<(__DATA_RUN__)
- sta ptr2
- lda #>(__DATA_RUN__)
- sta ptr2+1
-
- ldx #>(__DATA_SIZE__)
-@l2:
- beq @s1 ; no more full pages
-
- ; copy one page
- ldy #0
-@l1:
- lda (ptr1),y
- sta (ptr2),y
- iny
- bne @l1
-
- inc ptr1+1
- inc ptr2+1
-
- dex
- bne @l2
-
- ; copy remaining bytes
-@s1:
- ; copy one page
- ldy #0
-@l3:
- lda (ptr1),y
- sta (ptr2),y
- iny
- cpy #<(__DATA_SIZE__)
- bne @l3
-
- ; setup the stack
- lda #<(__RAM_START__+__RAM_SIZE__)
+ tii __DATA_LOAD__, __DATA_RUN__, __DATA_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
jsr initlib
jsr push0 ; argv
ldy #4 ; Argument size
- jsr _main ; call the users code
+ jsr _main ; Call the users code
; Call module destructors. This is also the _exit entry.
_exit:
; reset the PCEngine (start over)
jmp start
-; ------------------------------------------------------------------------
-; System V-Blank Interupt
-; FIXME: hooks should be provided so the user can abuse the IRQ
-; ------------------------------------------------------------------------
-
-_irq1:
- pha
- phx
- phy
-
- ; increment the system tick counter
- inc tickcount
- bne @s1
- inc tickcount + 1
- bne @s1
- inc tickcount + 2
- bne @s1
- inc tickcount + 3
-@s1:
- ; Acknowlege interrupt
- lda a:VDC_CTRL
-
- ply
- plx
- pla
- rti
-_irq2:
- rti
_nmi:
rti
-_timer:
- stz IRQ_STATUS
- rti
.export initmainargs
initmainargs:
; ------------------------------------------------------------------------
.segment "VECTORS"
- .word _irq2 ; $fff6 IRQ2 (External IRQ, BRK)
- .word _irq1 ; $fff8 IRQ1 (VDC)
- .word _timer ; $fffa Timer
+ .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