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kickstart.a65
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kickstart.a65
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; MEGA65 Kick Start ROM.
; Paul Gardner-Stephen, 2014-2016.
;
; Purpose:
; 1. Verify checksum of ROM area of slow RAM.
; 1. If checksum fails, load complete ROM from SD card.
; 2. Select default disk image for F011 emulation.
;
; The kickstart ROM is 16KB in length, and maps at $8000-$BFFF
; in hypervisor mode.
;
; Kickstart modifies RAM from $0000-$07FFF (ZP, stack, 40-column
; screen, 16-bit text mode) during normal boot.
;
; If Kickstart needs to load the ROM from SD card, then it may
; modify the first 64KB of fast ram.
;
; We will use the convention of C=0 means failure, and C=1 means
; success.
;
.include "kickstart_machine.a65"
; scratch space in ZP space usually used by kernel
; we try to use address space not normally used by C64 kernel, so that
; it is possible to make calls to kickstart after boot. Eventually
; the desire is to have an SYS call that brings up a menu that lets
; you choose a disk image from a list.
.data
.org $ce00
.space romslab 1
.space screenrow 1
.space checksum 4
.space file_pagesread 2
; variables for testing of D81 boot image
.space d81_clusternumber 4
.space d81_clustersneeded 2
.space d81_clustercount 2
; make sure that we don't go past the 256 byte page reserved for hypervisor scratch space
.checkpc $CEFF
.text
.org $8000
;;; ----------------------------------------------------------------------------
;;; CPU Hypervisor Trap entry points.
;;; 64 x 4 byte entries for user-land traps.
;;; some more x 4 byte entries for system traps (reset, page fault etc)
;;; ----------------------------------------------------------------------------
trap_entry_points:
; Traps $00-$07 (user callable)
jmp dos_and_process_trap
nop
jmp nosuchtrap
nop
jmp nosuchtrap
nop
jmp nosuchtrap
nop
jmp nosuchtrap
nop
jmp nosuchtrap
nop
jmp nosuchtrap
nop
jmp nosuchtrap
nop
; Traps $08-$0F (user callable)
jmp nosuchtrap
nop
jmp nosuchtrap
nop
jmp nosuchtrap
nop
jmp nosuchtrap
nop
jmp nosuchtrap
nop
jmp nosuchtrap
nop
jmp nosuchtrap
nop
jmp nosuchtrap
nop
; Traps $10-$17 (user callable)
jmp nosuchtrap
nop
jmp nosuchtrap
nop
jmp nosuchtrap
nop
jmp nosuchtrap
nop
jmp nosuchtrap
nop
jmp nosuchtrap
nop
jmp nosuchtrap
nop
jmp nosuchtrap
nop
; Traps $18-$1F (user callable)
jmp nosuchtrap
nop
jmp nosuchtrap
nop
jmp nosuchtrap
nop
jmp nosuchtrap
nop
jmp nosuchtrap
nop
jmp nosuchtrap
nop
jmp nosuchtrap
nop
jmp nosuchtrap
nop
; Traps $20-$27 (user callable)
jmp nosuchtrap
nop
jmp nosuchtrap
nop
jmp nosuchtrap
nop
jmp nosuchtrap
nop
jmp nosuchtrap
nop
jmp nosuchtrap
nop
jmp nosuchtrap
nop
jmp nosuchtrap
nop
; Traps $28-$2F (user callable)
jmp nosuchtrap
nop
jmp nosuchtrap
nop
jmp nosuchtrap
nop
jmp nosuchtrap
nop
jmp nosuchtrap
nop
jmp nosuchtrap
nop
jmp nosuchtrap
nop
jmp nosuchtrap
nop
; Traps $30-$37
jmp nosuchtrap
nop
jmp nosuchtrap
nop
jmp nosuchtrap
nop
jmp nosuchtrap
nop
jmp nosuchtrap
nop
jmp nosuchtrap
nop
jmp nosuchtrap
nop
jmp nosuchtrap
nop
; Traps $38-$3F (user callable)
jmp nosuchtrap
nop
jmp nosuchtrap
nop
jmp nosuchtrap
nop
jmp nosuchtrap
nop
jmp nosuchtrap
nop
jmp nosuchtrap
nop
jmp nosuchtrap
nop
jmp nosuchtrap
nop
; Traps $40-$4F (reset, page fault and other system-generated traps)
jmp reset_entry_allow_etherkick ; Trap #$40 (power on / reset)
nop
jmp page_fault ; Trap #$41 (page fault)
nop
jmp double_restore_trap ; Trap #$42 (double-tap RESTORE key)
nop
jmp nosuchtrap
nop
jmp nosuchtrap
nop
jmp nosuchtrap
nop
jmp nosuchtrap
nop
jmp nosuchtrap
nop
jmp nosuchtrap
nop
jmp nosuchtrap
nop
jmp nosuchtrap
nop
jmp nosuchtrap
nop
jmp nosuchtrap
nop
jmp nosuchtrap
nop
jmp nosuchtrap
nop
jmp nosuchtrap
nop
; Leave room for traps to $7E
.checkpc $81F8
.advance $81F8
; Then we have relocated CPU vectors
.word reset_entry_allow_etherkick ; unused vector
.word hypervisor_nmi ; NMI
.word reset_entry_allow_etherkick ; RESET
.word hypervisor_irq ; IRQ
.advance $8200
;;; ----------------------------------------------------------------------------
;;; Hypervisor traps
;;; ----------------------------------------------------------------------------
;;; ----------------------------------------------------------------------------
;;; Illegal trap / trap sub-function handlers
;;; ----------------------------------------------------------------------------
; Traps are triggered by writing to $D640-$D67F
; and trap to $8000+((address & $3F)*4) in the hypervisor
; Routine for unimplemented/reserved traps
; (Consider replacing with trap to hypervisor error screen with option
; to return?)
nosuchtrap:
; Clear C flag for caller to indicate failure
lda hypervisor_flags
and #$FE ; C flag is bit 0
sta hypervisor_flags
; set A to $FF
lda #$ff
sta hypervisor_a
; return from hypervisor
sta hypervisor_enterexit_trigger
; Return from trap with C flag clear to indicate success
return_from_trap_with_success:
jsr sd_unmap_sectorbuffer
; set C flag for caller to indicate success
lda hypervisor_flags
ora #$01 ; C flag is bit 0
sta hypervisor_flags
jsr checkpoint
.byte 0,"return_from_trap_with_success",0
; return from hypervisor
sta hypervisor_enterexit_trigger
return_from_trap_with_failure:
jsr sd_unmap_sectorbuffer
; report error in A
sta hypervisor_a
lda hypervisor_flags
and #$fe ; C flag is bit 0
sta hypervisor_flags
jsr checkpoint
.byte 0,"return_from_trap_with_failure",0
; return from hypervisor
sta hypervisor_enterexit_trigger
invalid_subfunction:
jmp nosuchtrap
;;; ----------------------------------------------------------------------------
;;; DOS, process control and related functions trap
;;; ----------------------------------------------------------------------------
.include "kickstart_dos.a65"
;;; ----------------------------------------------------------------------------
;;; Virtual memory and memory management
;;; ----------------------------------------------------------------------------
.include "kickstart_mem.a65"
;;; ----------------------------------------------------------------------------
;;; Task (process) management
;;; ----------------------------------------------------------------------------
.include "kickstart_task.a65"
;;; ----------------------------------------------------------------------------
;;; CPU Hypervisor Entry Point on reset
;;; ----------------------------------------------------------------------------
reset_machine_state:
; get CPU state sensible
sei
cld
see
; disable IRQ/NMI sources
lda #$7f
sta $DC0D
sta $DD0D
LDA #$00
STA $D019
sec
jsr enhanced_io
lda $d60d
; switch to fast mode
; 1. C65 fast-mode enable
lda $d031
ora #$40
sta $d031
; 2. MEGA65 48MHz enable (requires C65 or C128 fast mode to truly enable, hence the above)
lda $d054
ora #$40
sta $d054
; sprites off
lda #$00
sta $d017
lda #$7f
sta $DC0D
sta $DD0D
lda #$00
sta $D01A
; We DO NOT need to mess with $01, because
; the 4510 starts up with kickstart mapped at $8000-$BFFF
; enhanced ($FFD3xxx) IO page mapped at $D000,
; and fast RAM elsewhere.
; Disable reset watchdog, enable flat 32-bit addressing, don't engage
; ROM write protect (yet), do make ASC/DIN / CAPS LOCK control CPU speed.
; also force 4502 CPU personality (6502 personality is still incomplete)
; (The watchdog was added to catch reset problems where the machine
; would run off somewhere odd instead of resetting properly. Now it
; will auto-reset after 65535 cycles if the watchdog is not cleared).
lda #$2a
sta $d67d
jsr resetdisplay
jsr erasescreen
jsr resetpalette
jsr checkpoint
.byte 0,"reset_machine_state",0
rts
;;; ----------------------------------------------------------------------------
;;; CPU Hypervisor reset/trap routines
;;; ----------------------------------------------------------------------------
reset_entry_allow_etherkick:
sei
lda #$00
sta kickstart_boot_flags
jmp reset_entry_common
reset_entry_no_etherkick:
sei
lda #$80
sta kickstart_boot_flags
jmp reset_entry_common
reset_entry_common:
jsr reset_machine_state
; display welcome screen
ldx #<msg_kickstart
ldy #>msg_kickstart
jsr printbanner
; leave a blank line below kickstart banner
ldx #<msg_blankline
ldy #>msg_blankline
jsr printmessage
; Display GIT commit
ldx #<msg_gitcommit
ldy #>msg_gitcommit
jsr printmessage
; check keyboard for 0-9 down to select alternate rom
jsr keyboardread
; If switch 8 and 9 are set, and etherkick mode is not disabled
; then wait forever for ethernet packets
lda kickstart_boot_flags
bmi normalboot
lda $d6f1
and #$02
beq normalboot
etherboot:
ldx #<msg_etherkick
ldy #>msg_etherkick
jsr printmessage
jsr setupethernet
etherloop:
jsr checkethernet
.byte 0,"etherloop",0
jmp etherloop
normalboot:
; Try to read the MBR from the SD card to ensure SD card is
; happy
ldx #<msg_tryingsdcard
ldy #>msg_tryingsdcard
jsr printmessage
tryreadmbr:
jsr readmbr
bcs gotmbr
jmp tryreadmbr
gotmbr:
; Scan SD card for partitions and mount them.
jsr dos_clearall
jsr dos_read_partitiontable
ldx #<msg_diskcount
ldy #>msg_diskcount
jsr printmessage
ldy #$00
ldz dos_disk_count
jsr printhex
; Go to root directory on default disk
ldx dos_default_disk
jsr dos_cdroot
bcs mountsystemdiskok
ldx #<msg_cdrootfailed
ldy #>msg_cdrootfailed
jsr printmessage
ldy #$00
ldz dos_error_code
jsr printhex
mountsystemdiskok:
; Load and display boot logo
; Prepare 32-bit pointer for loading boot logo @ $0004000
lda #$00
sta <dos_file_loadaddress+0
lda #$40
sta <dos_file_loadaddress+1
lda #$00
sta <dos_file_loadaddress+2
lda #$00
sta <dos_file_loadaddress+3
ldx #<txt_bootlogo
ldy #>txt_bootlogo
jsr dos_setname
jsr dos_readfileintomemory
bcs logook
ldx #<msg_nologo
ldy #>msg_nologo
jsr printmessage
ldy #$00
ldz dos_error_code
jsr printhex
logook:
; iterate through directory entries looking for ordinary file
; KICKUP.M65 to load into hypervisor memory ...
; ... but only if we are not running a kick-up'd kickstart now.
lda $d67e
beq nextdirectoryentry3
; already kicked
ldx #<msg_alreadykicked
ldy #>msg_alreadykicked
jsr printmessage
jmp postkickup
nextdirectoryentry3:
; Prepare 32-bit pointer for loading boot logo @ $0004000
lda #$00
sta <dos_file_loadaddress+0
lda #$40
sta <dos_file_loadaddress+1
lda #$00
sta <dos_file_loadaddress+2
lda #$00
sta <dos_file_loadaddress+3
ldx #<txt_kickupfile
ldy #>txt_kickupfile
jsr dos_setname
jsr dos_readfileintomemory
bcc nokickup
; We have loaded kickup file, so jump into it.
ldx #<msg_kickuploaded
ldy #>msg_kickuploaded
jsr printmessage
ldy #$00
ldz <zptempv32+3
jsr printhex
ldz <zptempv32+2
jsr printhex
ldz <zptempv32+1
jsr printhex
ldz <zptempv32+0
jsr printhex
; Use DMAgic to copy $0004000-$0007FFF to $FFF8000-$FFFBFFF
; (We have to copy the routine to do this to RAM, since we will
; be replacing ourselves)
ldx #$00
krc: lda kickuproutine,x
sta $3000,x
inx
bne krc
jmp $3000
kickuproutine:
; The following routine gets copied as-is to $3000 and run from there.
; The DMA list is still available in the kickstart ROM when it gets
; called, so we can just use it there, instead of working out where
; it gets copied to
; Set bottom 22 bits of DMA list address as for C65
; (8MB address range). Kickstart ROM is at $FFF8000, so $FF goes
; in high-byte area
lda #$ff
sta $d702
lda #$ff
sta $d704 ; dma list is in top MB of address space
sta $d706 ; similarly destination of copy is top MB of address space
lda #$00
sta $d705 ; source of copy is bottom MB of address space
lda #>kickupdmalist
sta $d701
lda #<kickupdmalist
sta $d700
; clear source/destination MB so that C65 ROM doesn't go bananas
lda #$00
sta $d706
; copy complete, so mark ourselves upgraded, and jump into hypervisor
; as though we were just reset.
sta $d67e ; mark ourselves as having kicked up
jmp $8100
kickupdmalist:
; copy $0004000-$0007FFF to $FFF8000-$FFFBFFF
; (MB offsets get set in routine)
.byte $00 ; copy + last request in chain
.word $4000 ; size of copy is 16KB
.word $4000 ; starting at $4000
.byte $00 ; of bank $0
.word $8000 ; destination address is $8000
.byte $0F ; of bank $F
.word $0000 ; modulo (unused)
couldntopenkickup:
nokickup:
ldx #<msg_nokickup
ldy #>msg_nokickup
jsr printmessage
postkickup:
; MILESTONE: Have file system properties.
; Look for MEGA65.D81 to mount for F011 emulation
; for now indicate that there is no disk in drive
lda #$00
sta $d68b
jsr dos_cdroot
bcc sdcarderror
; set name of file we are looking for
ldx #<txt_c65gsd81
ldy #>txt_c65gsd81
jsr dos_setname
jsr dos_findfile
bcc nod81
jsr dos_closefile
jsr dos_d81attach
bcc d81attachfail
ldx #<msg_d81mounted
ldy #>msg_d81mounted
jsr printmessage
; all done, move on to loading the ROM
jmp findrom
d81attachfail:
; we couldn't find the D81 file, so tell the user
ldx #<msg_nod81
ldy #>msg_nod81
jsr printmessage
ldy #$00
ldz dos_error_code
jsr printhex
findrom:
; Check state of current ROM
jsr checkromok
bcc loadrom
; ROM is loaded and ready, so transfer control
; to it.
ldx #<msg_romok
ldy #>msg_romok
jsr printmessage
jmp go64
loadrom:
; ROM is not loaded, so try to load it, or prompt
; for user to insert SD card
ldx #<msg_rombad
ldy #>msg_rombad
jsr printmessage
; Load CHARROM.M65 into character ROM
ldx #<txt_c65gscharrom
ldy #>txt_c65gscharrom
jsr dos_setname
; Prepare 32-bit pointer for loading whole ROM ($FF7E000)
lda #$00
sta <dos_file_loadaddress+0
lda #$E0
sta <dos_file_loadaddress+1
lda #$F7
sta <dos_file_loadaddress+2
lda #$0F
sta <dos_file_loadaddress+3
jsr dos_readfileintomemory
bcs loadedcharromok
ldx #<msg_charrombad
ldy #>msg_charrombad
jsr printmessage
jmp loadc65rom
loadedcharromok:
ldx dos_current_file_descriptor_offset
lda dos_file_descriptors+dos_filedescriptor_offset_fileoffset+0,x
sta file_pagesread
lda dos_file_descriptors+dos_filedescriptor_offset_fileoffset+1,x
sta file_pagesread+1
ldx #<msg_charromloaded
ldy #>msg_charromloaded
jsr printmessage
ldy #$00
ldz file_pagesread+1
jsr printhex
ldz file_pagesread
jsr printhex
loadc65rom:
ldx #<txt_c65gsrom
ldy #>txt_c65gsrom
jsr dos_setname
; Prepare 32-bit pointer for loading whole ROM ($0020000)
lda #$00
sta <dos_file_loadaddress+0
sta <dos_file_loadaddress+1
sta <dos_file_loadaddress+3
lda #$02
sta <dos_file_loadaddress+2
jsr dos_readfileintomemory
bcs loadedok
; ROM not found: indicate which ROM we were looking for
ldx #$0b
l17d: lda txt_c65gsrom,x
sta msg_romnotfound+19,x
dex
bne l17d
ldx #<msg_romnotfound
ldy #>msg_romnotfound
jsr printmessage
jsr sdwaitawhile
jsr sdwaitawhile
jsr sdwaitawhile
jsr sdwaitawhile
jmp sdcarderror
loadedok:
ldx dos_current_file_descriptor_offset
lda dos_file_descriptors+dos_filedescriptor_offset_fileoffset+0,x
sta file_pagesread
lda dos_file_descriptors+dos_filedescriptor_offset_fileoffset+1,x
sta file_pagesread+1
lda file_pagesread
bne romfiletooshort
lda file_pagesread+1
cmp #$00
beq romfiletooshort
cmp #$02
bne romfiletoolong
; need to store checksum
jsr storeromsum
; ROM file loaded, transfer control
ldx #<msg_romok
ldy #>msg_romok
jsr printmessage
jmp go64
romfiletoolong:
ldx #<msg_romfilelongerror
ldy #>msg_romfilelongerror
jsr printmessage
ldz file_pagesread+1
jsr printhex
ldz file_pagesread
jsr printhex
jsr sdwaitawhile
jmp reset_entry_allow_etherkick
romfiletooshort:
ldx #<msg_romfileshorterror
ldy #>msg_romfileshorterror
jsr printmessage
ldz file_pagesread+1
jsr printhex
ldz file_pagesread
jsr printhex
jsr sdwaitawhile
jmp reset_entry_allow_etherkick
fileopenerror:
ldx #<msg_fileopenerror
ldy #>msg_fileopenerror
jsr printmessage
sdcarderror: ldx #<msg_sdcarderror
ldy #>msg_sdcarderror
jsr printmessage
jsr sdwaitawhile
jmp reset_entry_allow_etherkick
badfs: ldx #<msg_badformat
ldy #>msg_badformat
jsr printmessage
jsr sdwaitawhile
jmp reset_entry_allow_etherkick
;;; ----------------------------------------------------------------------------
;;; FAT file system routines
;;; ----------------------------------------------------------------------------
toupper: ; convert ASCII character to upper case
cmp #$60
bcc tu1
cmp #$7a
bcs tu1
and #$5f
tu1: rts
;;; ----------------------------------------------------------------------------
;;; MBP / partition routines
;;; ----------------------------------------------------------------------------
; read master boot record. Does not sanity check anything.
readmbr:
; begin by resetting SD card
jsr sdreset
bcs l7
rts
l7: ldx #<msg_foundsdcard
ldy #>msg_foundsdcard
jsr printmessage
; MBR is sector 0
lda #$00
sta $D681
sta $d682
sta $d683
sta $d684
jmp sd_readsector
;;; ----------------------------------------------------------------------------
;;; SD Card access routines
;;; ----------------------------------------------------------------------------
sdreset:
; try SD-HC mode first
; lda #$41
; sta $D680
; jsr sd_resetsequence
; bcc sdr1
; rts
sdr1: ; fall back to SD mode
lda #$42
sta $d680
; fall through
sd_resetsequence:
; write $00 to $D680 to start reset
lda #$00
sta $D680
jsr sdtimeoutreset
re1: jsr sdreadytest
bcs re1done ; success, so return
bne re1 ; not timed out, so keep trying
rts ; timeout, so return
re1done:
; write $01 to $D680 to complete reset
lda #$01
sta $D680
jsr sdtimeoutreset
re2: jsr sdreadytest
bcs re2done ; success, so return
bne re2 ; not timed out, so keep trying
rts ; timeout, so return
re2done:
; give card some time to settle after reset, otherwise
; reading sectors will fail
jsr sdwaitawhile
jsr sd_map_sectorbuffer
; write $02 to $D680 to read MBR as a test of reset
lda #$02
sta $D680
jsr sdtimeoutreset
re3: ; allow time for read to happen
lda $d680
jsr sdreadytest
bcs redone ; success, so return
bne re3 ; not timed out, so keep trying
; timeout -- so call reset again
rts
redone:
sec
rts
; Watch for ethernet packets while waiting for the SD card.
; this allows loading of code into the hypervisor for testing and
; bare-metal operation.
sdwaitawhile: jsr sdtimeoutreset
sw1:
inc $d020
jsr checkethernet
dec $d020
inc $0300
bne sw1
inc $0301
bne sw1
inc $0302
bne sw1
rts
; count to timeout value when trying to read from SD card
; (if it is too short, the SD card won't reset)
sdtimeoutreset:
lda #$00
sta $0300
sta $0301
lda #$f7
sta $0302
rts
sdreadytest: ; check if SD card is ready, or if timeout has occurred
; C is set if ready.
; Z is set if timeout has occurred.
lda $d680
and #$03
beq sdisready
inc $0300
bne sr1
inc $0301
bne sr1
inc $0302
bne sr1
; timeout
lda #$00 ; set Z
sr1: clc
rts
sdisready: sec
rts
sd_map_sectorbuffer:
lda #$81
sta $D680
sec
rts
sd_unmap_sectorbuffer:
pha
lda #$82
sta $D680
pla
sec
rts
sd_readsector:
; Assumes fixed sector number (or byte address in case of SD cards)
; is loaded into $D681 - $D684
; check if sd card is busy
lda $d680
and #$01
bne rsbusyfail
; try reading sector fast the first time
jmp rs4
redoread:
; when retrying, introduce a delay. This seems to be needed often
; when reading the first sector after SD card reset.
ldx #$f0
ldy #$00
ldz #$00
r1: inz
bne r1
iny
bne r1
inx
bne r1
rs4:
; ask for sector to be read
lda #$02
sta $d680
; wait for sector to be read
jsr sdtimeoutreset
rs3:
jsr sdreadytest
bcs rsread
bne rs3
jmp rereadsector
rsread:
lda $d680
and #$01
bne rs3
; check that we read 512 bytes
lda $d688
lda $d689
cmp #$02
bne redoread
sec
rts
; reset sd card and try again
rereadsector:
jsr sdreset
jmp rs4
rsbusyfail: ; fail
lda #dos_errorcode_read_timeout
sta dos_error_code
clc
rts
printsectoraddress:
ldx #<msg_sectoraddress