prodos-drivers/ns.clock.system.s

;;; NS.CLOCK.SYSTEM
;;; Original by "CAP" 04/21/91
;;; http://www.apple2.org.za/gswv/a2zine/GS.WorldView/v1999/Oct/MISC/NSC.Disk.TXT

;;; Modification history available at:
;;; https://github.com/inexorabletash/cricket

        .setcpu "6502"
        .linecont +

        .include "apple2.inc"
        .include "opcodes.inc"

        .include "./common.inc"


;;; ------------------------------------------------------------

        data_buffer = $1800

        .define SYSTEM_SUFFIX ".SYSTEM"
        .define PRODUCT "No-Slot Clock"

;;; ------------------------------------------------------------

        .org $1000

        ;;  Loaded at $2000 but relocates to $1000

;;; ------------------------------------------------------------

sys_start:
        sec
        bcs     relocate

        .byte   MM, DD, YY      ; version date stamp

;;; ------------------------------------------------------------
;;; Relocate this code from $2000 (.SYSTEM start location) to $1000
;;; and start executing there. This is done so that the next .SYSTEM
;;; file can be loaded/run at $2000.

.proc relocate
        src := SYS_ADDR
        dst := $1000

        ldx     #(sys_end - sys_start + $FF) / $100 ; pages
        ldy     #0
load:   lda     src,y           ; self-modified
        load_hi := *-1
        sta     dst,y           ; self-modified
        store_hi := *-1
        iny
        bne     load
        inc     load_hi
        inc     store_hi
        dex
        beq     find_self_name  ; done
        jmp     load
.endproc

;;; ------------------------------------------------------------
;;; Identify the name of this SYS file, which should be present at
;;; $280 with or without a path prefix. This is used when searching
;;; for the next .SYSTEM file to execute.

.proc find_self_name
        ;; Search pathname buffer backwards for '/', then
        ;; copy name into |self_name|; this is used later
        ;; to find/invoke the next .SYSTEM file.

        ;; Find '/' (which may not be present, prefix is optional)
        lda     #0
        sta     $A8
        ldx     PATHNAME
        beq     pre_install
floop:  inc     $A8
        dex
        beq     copy
        lda     PATHNAME,x
        eor     #'/'
        asl     a
        bne     floop

        ;; Copy name into |self_name| buffer
copy:   ldy     #0
cloop:  iny
        inx
        lda     PATHNAME,x
        sta     self_name,y
        cpy     $A8
        bcc     cloop
        sty     self_name
.endproc
        ;; Fall through...

;;; ------------------------------------------------------------
;;; Before installing, get the system to a known state and
;;; ensure there is not a previous clock driver installed.

.proc pre_install
        cld
        bit     ROMIN2

        ;; Update reset vector - re-invokes this code.
        lda     #<pre_install
        sta     $03F2
        lda     #>pre_install
        sta     $03F3
        eor     #$A5
        sta     $03F4

        ;; Quit 80-column firmware
        lda     #$95            ; Ctrl+U (quit 80 col firmware)
        jsr     COUT

        ;; Reset stack
        ldx     #$FF
        txs

        ;; Reset I/O
        sta     CLR80VID
        sta     CLRALTCHAR
        jsr     SETVID
        jsr     SETKBD
        jsr     SETNORM
        jsr     INIT

        ;; Update System Bit Map
        ldx     #BITMAP_SIZE-1
        lda     #%00000001      ; protect page $BF
:       sta     BITMAP,x
        lda     #%00000000      ; nothing else protected until...
        dex
        bne     :-
        lda     #%11001111      ; ZP ($00), stack ($01), text page 1 ($04-$07)
        sta     BITMAP

        lda     MACHID
        and     #$88            ; IIe or IIc (or IIgs) ?
        bne     :+
        lda     #$DF
        sta     lowercase_mask  ; lower case to upper case

:       lda     MACHID
        and     #$01            ; existing clock card?
        beq     detect_nsc      ; nope, check for NSC

        ;; Chain with no message
        jmp     launch_next_sys_file
.endproc

;;; ------------------------------------------------------------
;;; Detect NSC. Scan slot ROMs and main ROMs. Try reading
;;; each location several times, and validate results before
;;; installing driver.

.proc detect_nsc
        ;; Preserve date/time
        ldy     #3              ; copy 4 bytes
:       lda     DATELO,y
        sta     saved,y
        dey
        bpl     :-

        ;; Check slot ROMs
        lda     #>$CFFF
        ldy     #<$CFFF
        sta     ld4+2
        sty     ld4+1
        sta     st4+2
        sty     st4+1
        lda     #0
        sta     slot
        lda     #3              ; treat slot 0 as slot 3

sloop:  ora     #$C0            ; A=$Cs
        sta     st1+2
rloop:  sta     ld1+2
        sta     ld2+2
        sta     st2+2

        lda     #3              ; 3 tries - need valid results each time
        sta     tries
try:    jsr     driver          ; try reading date/time
        lda     DATELO+1        ; check result
        ror     a
        lda     DATELO
        rol     a
        rol     a
        rol     a
        rol     a
        and     #$0F
        beq     next
        cmp     #13             ; month
        bcs     next
        lda     DATELO
        and     #$1F
        beq     next
        cmp     #32             ; day
        bcs     next
        lda     TIMELO+1
        cmp     #24             ; hours
        bcs     next
        lda     TIMELO
        cmp     #60             ; minutes
        bcs     next
        dec     tries
        bne     try
        beq     install_driver  ; all tries look valid
next:   inc     slot
        lda     slot
        cmp     #8
        bcc     sloop           ; next slot
        bne     not_found

        ;; Not found in slot ROM, try main ROMs ???
        lda     #>$C015
        ldy     #<$C015
        sta     ld4+2
        sty     ld4+1
        ldy     #$07
        sta     st1+2
        sty     st1+1
        dey
        sta     st4+2
        sty     st4+1
        lda     #>$C800
        bne     rloop

        ;; Restore date/time
not_found:
        ldy     #3
:       lda     saved,y
        sta     DATELO,y
        dey
        bpl     :-

        ;; Show failure message
        jsr     MON_HOME
        jsr     zstrout
        HIASCIIZ CR, CR, CR, PRODUCT, " - Not Found."
        jmp     launch_next_sys_file

saved:  .byte   0, 0, 0, 0
tries:  .byte   3
slot:   .byte   0
.endproc

;;; ------------------------------------------------------------
;;; Install NSC Driver. Copy into address at DATETIME vector,
;;; update the vector and update MACHID bits to signal a clock
;;; is present.

.proc install_driver
        ptr := $A5

        lda     DATETIME+1
        sta     ptr
        clc
        adc     #(unlock - driver - 1)
        sta     ld3+1
        lda     DATETIME+2
        sta     ptr+1
        adc     #0
        sta     ld3+2
        lda     RWRAM1
        lda     RWRAM1
        ldy     #sizeof_driver-1

loop:   lda     driver,y
        sta     (ptr),y
        dey
        bpl     loop

        ;; Set the "Recognizable Clock Card" bit
        lda     MACHID
        ora     #$01
        sta     MACHID

        lda     #OPC_JMP_abs
        sta     DATETIME

        ;; Invoke the driver to init the time
        jsr     DATETIME

        ;; Display success message
        bit     ROMIN2
        jsr     MON_HOME
        jsr     zstrout
        HIASCIIZ CR, CR, CR, PRODUCT, " - Installed  "

        ;; Display the current date
        lda     DATELO+1        ; month
        ror     a
        pha
        lda     DATELO
        pha
        rol     a
        rol     a
        rol     a
        rol     a
        and     #%00001111
        jsr     cout_number

        lda     #(HI '/')       ; /
        jsr     COUT

        pla                     ; day
        and     #%00011111
        jsr     cout_number

        lda     #(HI '/')       ; /
        jsr     COUT

        pla                     ; year
        jsr     cout_number
        jsr     CROUT
.endproc

;;; ------------------------------------------------------------
;;; Find and invoke the next .SYSTEM file

.proc launch_next_sys_file
        ;; Update reset vector - now terminates.
        lda     #<quit
        sta     $03F2
        lda     #>quit
        sta     $03F3
        eor     #$A5
        sta     $03F4

        ptr := $A5
        num := $A7
        len := $A8

        lda     DEVNUM          ; stick with most recent device
        sta     read_block_params_unit_num
        jsr     read_block

        lda     data_buffer + VolumeDirectoryBlockHeader::entry_length
        sta     entry_length_mod
        lda     data_buffer + VolumeDirectoryBlockHeader::entries_per_block
        sta     entries_per_block_mod
        lda     #1
        sta     num

        lda     #<(data_buffer + VolumeDirectoryBlockHeader::header_length)
        sta     ptr
        lda     #>(data_buffer + VolumeDirectoryBlockHeader::header_length)
        sta     ptr+1

        ;; Process directory entry
entry:  ldy     #FileEntry::file_type      ; file_type
        lda     (ptr),y
        cmp     #$FF            ; type=SYS
        bne     next
        ldy     #FileEntry::storage_type
        lda     (ptr),y
        and     #$30            ; regular file (not directory, pascal)
        beq     next
        lda     (ptr),y
        and     #$0F            ; name_length
        sta     len
        tay

        ;; Compare suffix - is it .SYSTEM?
        ldx     #.strlen(SYSTEM_SUFFIX)-1
:       lda     (ptr),y
        cmp     suffix,x
        bne     next
        dey
        dex
        bpl     :-

        ;; Yes; is it *this* .SYSTEM file?
        ldy     self_name
        cpy     len
        bne     handle_sys_file
:       lda     (ptr),y
        cmp     self_name,y
        bne     handle_sys_file
        dey
        bne     :-
        sec
        ror     found_self_flag

        ;; Move to the next entry
next:   lda     ptr
        clc
        adc     #$27            ; self-modified: entry_length
        entry_length_mod := *-1
        sta     ptr
        bcc     :+
        inc     ptr+1
:       inc     num
        lda     num
        cmp     #$0D            ; self-modified: entries_per_block
        entries_per_block_mod := *-1
        bcc     entry

        lda     data_buffer + VolumeDirectoryBlockHeader::next_block
        sta     read_block_params_block_num
        lda     data_buffer + VolumeDirectoryBlockHeader::next_block + 1
        sta     read_block_params_block_num+1
        ora     read_block_params_block_num
        beq     not_found       ; last block has next=0
        jsr     read_block
        lda     #0
        sta     num
        lda     #<(data_buffer + $04)
        sta     ptr
        lda     #>(data_buffer + $04)
        sta     ptr+1
        jmp     entry

        ;; Found a .SYSTEM file which is not this one; invoke
        ;; it if follows this one.
handle_sys_file:
        bit     found_self_flag
        bpl     next

        ;; Compose the path to invoke. First walk self path
        ;; backwards to '/'.
        ldx     PATHNAME
        beq     append
:       dex
        beq     append
        lda     PATHNAME,x
        eor     #'/'
        asl     a
        bne     :-

        ;; Now append name of found file.
append: ldy     #0
:       iny
        inx
        lda     (ptr),y
        sta     PATHNAME,x
        cpy     len
        bcc     :-
        stx     PATHNAME
        jmp     invoke_system_file

not_found:
        jsr     zstrout
        HIASCIIZ CR, CR, CR, "* Unable to find next '.SYSTEM' file *", CR
        bit     KBDSTRB
:       lda     KBD
        bpl     :-
        bit     KBDSTRB
        jmp     quit
.endproc

;;; ------------------------------------------------------------
;;; Output a high-ascii, null-terminated string.
;;; String immediately follows the JSR.

.proc zstrout
        ptr := $A5

        pla                     ; read address from stack
        sta     ptr
        pla
        sta     ptr+1
        bne     skip            ; always (since data not on ZP)

next:   cmp     #(HI 'a')       ; lower-case?
        bcc     :+
        and     lowercase_mask  ; make upper-case if needed
:       jsr     COUT
skip:   inc     ptr
        bne     :+
        inc     ptr+1
:       ldy     #0
        lda     (ptr),y
        bne     next

        lda     ptr+1           ; restore address to stack
        pha
        lda     ptr
        pha
        rts
.endproc

;;; ------------------------------------------------------------
;;; COUT a 2-digit number in A

.proc cout_number
        ldx     #(HI '0')
        cmp     #10             ; >= 10?
        bcc     tens

        ;; divide by 10, dividend(+'0') in x remainder in a
:       sbc     #10
        inx
        cmp     #10
        bcs     :-

tens:   pha
        cpx     #(HI '0')
        beq     units
        txa
        jsr     COUT

units:  pla
        ora     #(HI '0')
        jsr     COUT
        rts
.endproc

;;; ------------------------------------------------------------

lowercase_mask:
        .byte   $FF             ; Set to $DF on systems w/o lower-case

;;; ------------------------------------------------------------
;;; Invoke ProDOS QUIT routine.

.proc quit
        PRODOS_CALL MLI_QUIT, quit_params
        .byte   0               ; crash if QUIT fails
        rts
.proc quit_params
        .byte   4               ; param_count
        .byte   0               ; quit_type
        .word   0000            ; reserved
        .byte   0               ; reserved
        .word   0000            ; reserved
.endproc
.endproc

;;; ------------------------------------------------------------
;;; Read a disk block.

.proc read_block
        PRODOS_CALL MLI_READ_BLOCK, read_block_params
        bcs     on_error
        rts
.endproc

.proc read_block_params
        .byte   3               ; param_count
unit_num:  .byte   $60          ; unit_num
        .addr   data_buffer     ; data_buffer
block_num: .word   2            ; block_num - block 2 is volume directory
.endproc
        read_block_params_unit_num := read_block_params::unit_num
        read_block_params_block_num := read_block_params::block_num

;;; ------------------------------------------------------------
;;; Load/execute the system file in PATHNAME

.proc invoke_system_file
        PRODOS_CALL MLI_OPEN, open_params
        bcs     on_error

        lda     open_params_ref_num
        sta     read_params_ref_num

        PRODOS_CALL MLI_READ, read_params
        bcs     on_error

        PRODOS_CALL MLI_CLOSE, close_params
        bcs     on_error

        jmp     SYS_ADDR        ; Invoke loaded SYSTEM file
.endproc

;;; ------------------------------------------------------------
;;; Error handler - invoked if any ProDOS error occurs.

.proc on_error
        pha
        jsr     zstrout
        HIASCIIZ CR, CR, CR, "**  Disk Error $"
        pla
        jsr     PRBYTE
        jsr     zstrout
        HIASCIIZ "  **", CR
        bit     KBDSTRB
:       lda     KBD
        bpl     :-
        bit     KBDSTRB
        jmp     quit
.endproc

;;; ------------------------------------------------------------

.proc open_params
        .byte   3               ; param_count
        .addr   PATHNAME        ; pathname
        .addr   data_buffer     ; io_buffer
ref_num:.byte   1               ; ref_num
.endproc
        open_params_ref_num := open_params::ref_num

.proc read_params
        .byte   4               ; param_count
ref_num:.byte   1               ; ref_num
        .addr   SYS_ADDR        ; data_buffer
        .word   MAX_DW          ; request_count
        .word   0               ; trans_count
.endproc
        read_params_ref_num := read_params::ref_num

.proc close_params
        .byte   1               ; param_count
ref_num:.byte   0               ; ref_num
.endproc

;;; ------------------------------------------------------------

found_self_flag:
        .byte   0

suffix: .byte   SYSTEM_SUFFIX

self_name:
        PASCAL_STRING "NS.CLOCK.SYSTEM"

;;; ------------------------------------------------------------
;;; NSC driver - modified as needed and copied into ProDOS

driver:
        php
        sei
ld4:    lda     $CFFF           ; self-modified
        pha
st1:    sta     $C300           ; self-modified
ld1:    lda     $C304           ; self-modified
        ldx     #8

        ;; Unlock the NSC by bit-banging.
uloop:
ld3:    lda     unlock-1,x      ; self-modified
        sec
        ror     a               ; a bit at a time
:       pha
        lda     #0
        rol     a
        tay
ld2:    lda     $C300,y         ; self-modified
        pla
        lsr     a
        bne     :-
        dex
        bne     uloop

        ;; Read 8 bytes * 8 bits of clock data into $200...$207
        ldx     #8
bloop:  ldy     #8
st2:
:       lda     $C304           ; self-modified
        ror     a
        ror     $01FF,x
        dey
        bne     :-
        lda     $01FF,x         ; got 8 bits

        lsr     a               ; BCD to binary
        lsr     a               ; shift out tens
        lsr     a
        lsr     a
        tay
        beq     donebcd
        lda     $01FF,x
        and     #$0F            ; mask out units
        clc
:       adc     #10             ; and add tens as needed
        dey
        bne     :-
        sta     $01FF,x
donebcd:
        dex
        bne     bloop

        ;; Now $200...$207 is y/m/d/w/H/M/S/f

        ;; Update ProDOS date/time.
        lda     $0204           ; hour
        sta     TIMELO+1

        lda     $0205           ; minute
        sta     TIMELO

        lda     $0201           ; month
        asl     a
        asl     a
        asl     a
        asl     a
        asl     a

        ora     $0202           ; day
        sta     DATELO

        lda     $0200           ; year
        rol     a
        sta     DATELO+1

        pla
        bmi     done
st4:    sta     $CFFF           ; self-modified
done:   plp
        rts

unlock:
        ;; NSC unlock sequence
        .byte   $5C, $A3, $3A, $C5
        .byte   $5C, $A3, $3A, $C5
        .byte   $00

        sizeof_driver := * - driver
        .assert sizeof_driver <= 125, error, "Clock code must be <= 125 bytes"

;;; ------------------------------------------------------------

sys_end: