ftp.barnyard.co.uk/2015.02.ftp.barnyard.co.uk.tar/ftp.barnyard.co.uk/cpm/walnut-creek-CDROM/ENTERPRS/CPM/UTILS/A/BIOSR4.ARC/CXKRNL.ASM

Assembly Source File | 1987-04-26 | 16KB | 763 lines

    title    'Root module of relocatable BIOS for CP/M 3.0 28 Aug 85'

; version 1.0    5 Sept 84


    maclib    cxequ            ; C128 equates lib

    maclib    modebaud        ; define mode bits

    maclib    Z80

;          Copyright (C), 1982
;         Digital Research, Inc
;             P.O. Box 579
;        Pacific Grove, CA  93950
;
;
;   This is the invariant portion of the modular BIOS and is
;    distributed as source for informational purposes only.
;    All desired modifications should be performed by
;    adding or changing externally defined modules.
;    This allows producing "standard" I/O modules that
;    can be combined to support a particular system
;    configuration.

bell    equ    7
ctlQ    equ    'Q'-'@'
ctlS    equ    'S'-'@'

ccp    equ    0100h            ; Console Command Processor
                    ; gets loaded into the TPA

    page

    cseg                ; GENCPM puts CSEG stuff in
                    ; common memory

; variables in system data page

    extrn    @covec,@civec
    extrn    @aovec
    extrn    @aivec,@lovec        ; I/O redirection vectors
    extrn    @mxtpa            ; addr of system entry point
    extrn    @bnkbf            ; 128 byte scratch buffer

; initialization

    extrn    ?init            ; general initialization and signon
    extrn    ?ldccp,?rlccp        ; load & reload CCP for BOOT & WBOOT

; user defined character I/O routines

    extrn    ?ci,?co,?cist,?cost    ; each take device in <B>
    extrn    ?cinit            ; (re)initialize device in <C>
    extrn    @ctbl            ; physical character device table

; disk communication data items

    extrn    @dtbl            ; table of pointers to XDPHs

; memory control

    extrn    ?xmove,?move        ; select move bank, and block move
    extrn    ?bank            ; select CPU bank

; clock support

    extrn    ?time            ; signal time operation

;; user function

    extrn    ?user            ; special functions

; general utility routines

    public    ?pmsg            ; print message
    public    ?pdec             ; print number from 0 to 65535
    public    ?pderr            ; print BIOS disk error message header


    page

; External names for BIOS entry points

    public    ?boot,?wboot,?const,?conin,?cono,?list,?auxo,?auxi
    public    ?home,?sldsk,?sttrk,?stsec,?stdma,?read,?write
    public    ?lists,?sctrn
    public    ?conos,?auxis,?auxos,?dvtbl,?devin,?drtbl
    public    ?mltio,?flush,?mov,?tim,?bnksl,?stbnk,?xmov


; BIOS Jump vector.
;
; All BIOS routines are invoked by calling these
;    entry points.

?boot:    jmp    boot        ; initial entry on cold start
?wboot:    jmp    wboot        ; reentry on program exit, warm start

?const:    jmp    const        ; return console input status
?conin:    jmp    conin        ; return console input character
?cono:    jmp    conout        ; send console output character
?list:    jmp    list        ; send list output character
?auxo:    jmp    auxout        ; send auxilliary output character
?auxi:    jmp    auxin        ; return auxilliary input character

?home:    jmp    home        ; set disks to logical home
?sldsk:    jmp    seldsk        ; select disk drive, return disk parameter info
?sttrk:    jmp    settrk        ; set disk track
?stsec:    jmp    setsec        ; set disk sector
?stdma:    jmp    setdma        ; set disk I/O memory address
?read:    jmp    read        ; read physical block(s)
?write:    jmp    write        ; write physical block(s)

?lists:    jmp    listst        ; return list device status
?sctrn:    jmp    sectrn        ; translate logical to physical sector

?conos:    jmp    conost        ; return console output status
?auxis:    jmp    auxist        ; return aux input status
?auxos:    jmp    auxost        ; return aux output status
?dvtbl:    jmp    devtbl        ; return address of device def table
?devin:    jmp    ?cinit        ; change baud rate of device

?drtbl:    jmp    getdrv        ; return address of disk drive table
?mltio:    jmp    multio        ; set multiple record count for disk I/O
?flush:    jmp    flush        ; flush BIOS maintained disk caching

?mov:    jmp    ?move        ; block move memory to memory
?tim:    jmp    ?time        ; Signal Time and Date operation
?bnksl:    jmp    bnksel        ; select bank for code execution
                ; and default DMA
?stbnk:    jmp    setbnk        ; select different bank for disk
                ; I/O DMA operations.
?xmov:    jmp    ?xmove        ; set source and destination banks
                ; for one operation

    jmp    ?user        ; reserved for future expansion
    jmp    0        ; reserved for future expansion
    jmp    0        ; reserved for future expansion

    page
;
; BOOT
;    Initial entry point for system startup.

    dseg            ; this part can be banked
boot:
    lxi    sp,boot$stack
    mvi    c,15        ; initialize all 16 character devices
c$init$loop:
    push    b
    call    ?cinit
    pop    b
    dcr    c
    jp    c$init$loop

    call    ?init        ; perform any additional system initialization
                ; and print signon message
    lxi    b,16*256+0
    lxi    h,@dtbl        ; init all 16 logical disk drives
d$init$loop:
    push    b        ; save remaining count and abs drive
    mov    e,m
    inx    h
    mov    d,m
    inx    h        ; grab @drv entry
    mov    a,e
    ora    d
    jrz    d$init$next    ; if null, no drive

    push    h        ; save @drv pointer
    xchg            ; XDPH address in <HL>
    dcx    h
    dcx    h
    mov    a,m
    sta    @RDRV        ; get relative drive code
    mov    a,c
    sta    @ADRV        ; get absolute drive code
    dcx    h        ; point to init pointer
    mov    d,m
    dcx    h
    mov    e,m        ; get init pointer
    xchg
    call    ipchl        ; call init routine
    pop    h        ; recover @drv pointer
d$init$next:
    pop    b        ; recover counter and drive #
    inr    c
    djnz    d$init$loop    ; and loop for each drive
    jmp    boot$1

    cseg            ; following in resident memory
boot$1:
    call    set$jumps
    call    ?ldccp        ; fetch CCP for first time
    jmp    ccp

    page

; WBOOT
;    Entry for system restarts.

wboot:
    lxi    sp,boot$stack
    call    set$jumps    ; initialize page zero
    call    ?rlccp        ; reload CCP
    jmp    ccp        ; then reset jmp vectors and exit to ccp


set$jumps:

 if banked
    mvi    a,1
    call    ?bnksl
 endif

    mvi    a,JMP
    sta    0
    sta    5        ; set up jumps in page zero
    lxi    h,?wboot
    shld    1        ; BIOS warm start entry
    lhld    @MXTPA
    shld    6        ; BDOS system call entry
    ret


        ds 64
boot$stack    equ $

    page
;
; DEVTBL
;    Return address of character device table
devtbl:
    lxi    h,@ctbl
    ret

;
; GETDRV
;    Return address of drive table
getdrv:
    lxi    h,@dtbl
    ret


;
; CONOUT
;    Console Output.  Send character in <C>
;            to all selected devices
conout:
    lhld    @covec        ; fetch console output bit vector
    jmp    out$scan


;
; AUXOUT
;    Auxiliary Output. Send character in <C>
;            to all selected devices
auxout:
    lhld    @aovec        ; fetch aux output bit vector
    jmp    out$scan


;
; LIST
;    List Output.  Send character in <C>
;            to all selected devices.
list:
    lhld    @lovec        ; fetch list output bit vector

out$scan:
    mvi    b,0        ; start with device 0
co$next:
    dad    h        ; shift out next bit
    jrnc    not$out$device
    push    h        ; save the vector
    push    b        ; save the count and character
not$out$ready:
    call    coster
    ora    a
    jrz    not$out$ready
    pop    b
    push    b        ; restore and resave the character and device
    call    ?co        ; if device selected, print it
    pop    b        ; recover count and character
    pop    h        ; recover the rest of the vector
not$out$device:
    inr    b        ; next device number
    mov    a,h
    ora    l        ; see if any devices left
    jrnz    co$next        ; and go find them...
    ret

    page
;
; CONOST
;    Console Output Status.  Return true if
;        all selected console output devices
;        are ready.
conost:
    lhld    @covec        ; get console output bit vector
    jr    ost$scan


;
; AUXOST
;    Auxiliary Output Status.  Return true if
;        all selected auxiliary output devices
;        are ready.
auxost:
    lhld    @aovec        ; get aux output bit vector
    jr    ost$scan


;
; LISTST
;    List Output Status.  Return true if
;        all selected list output devices
;        are ready.
listst:
    lhld    @lovec        ; get list output bit vector

ost$scan:
    mvi    b,0        ; start with device 0
cos$next:
    dad    h        ; check next bit
    push    h        ; save the vector
    push    b        ; save the count
    mvi    a,0FFh        ; assume device ready
    cc    coster        ; check status for this device
    pop    b        ; recover count
    pop    h        ; recover bit vector
    ora    a        ; see if device ready
    rz            ; if any not ready, return false
    inr    b        ; drop device number
    mov    a,h
    ora    l        ; see if any more selected devices
    jrnz    cos$next
    ori    0FFh        ; all selected were ready, return true
    ret

coster:                ; check for output device ready,
                ; including optional xon/xoff support
    mov    l,b
    mvi    h,0        ; make device code 16 bits
    push    h        ; save it in stack
    dad    h
    dad    h        ; create offset into device
    dad    h        ; characteristics tbl
    lxi    d,@ctbl+6
    dad    d        ; make address of mode byte
    mov    a,m
    ani    mb$xonxoff
    pop    h        ; recover console number in <HL>
    jz    ?cost        ; not a xon device, go get output status direct
    lxi    d,xofflist
    dad    d        ; make pointer to proper xon/xoff flag
    call    cist1        ; see if this keyboard has character
    mov    a,m
    cnz    ci1        ; get flag or read key if any
    cpi    ctlq
    jrnz    not$q        ; if its a ctl-Q,
    mvi    a,0FFh         ;    set the flag ready
not$q:
    cpi    ctls
    jrnz    not$s        ; if its a ctl-S,
    mvi    a,00h        ;    clear the flag
not$s:
    mov    m,a        ; save the flag
    call    cost1        ; get the actual output status,
    ana    m        ; and mask with ctl-Q/ctl-S flag
    ret            ; return this as the status

cist1:                ; get input status with <BC> and <HL> saved
    push    b
    push    h
    call    ?cist
    pop    h
    pop    b
    ora    a
    ret

cost1:                ; get output status, saving <BC> & <HL>
    push    b
    push    h
    call    ?cost
    pop    h
    pop    b
    ora    a
    ret

ci1:                ; get input, saving <BC> & <HL>
    push    b
    push    h
    call    ?ci
    pop    h
    pop    b
    ret

    page
;
; CONST
;    Console Input Status.  Return true if
;        any selected console input device
;        has an available character.
const:
    lhld    @civec        ; get console input bit vector
    jr    ist$scan


;
; AUXIST
;    Auxiliary Input Status.  Return true if
;        any selected auxiliary input device
;        has an available character.
auxist:
    lhld    @aivec        ; get aux input bit vector

ist$scan:
    mvi    b,0        ; start with device 0
cis$next:
    dad    h        ; check next bit
    mvi    a,0        ; assume device not ready
    cc    cist1        ; check status for this device
    ora    a
    rnz            ; if any ready, return true
    inr    b        ; drop device number
    mov    a,h
    ora    l        ; see if any more selected devices
    jrnz    cis$next
    xra    a        ; all selected were not ready, return false
    ret

    page
;
; CONIN
;    Console Input.  Return character from first
;        ready console input device.
conin:
    lhld    @civec
    jr    in$scan


; AUXIN
;    Auxiliary Input.  Return character from first
;        ready auxiliary input device.
auxin:
    lhld    @aivec

in$scan:
    push    h        ; save bit vector
    mvi    b,0
ci$next:
    dad    h        ; shift out next bit
    mvi    a,0        ; insure zero a  (nonexistant device not ready).
    cc    cist1        ; see if the device has a character
    ora    a
    jrnz    ci$rdy        ; this device has a character
    inr    b        ; else, next device
    mov    a,h
    ora    l        ; see if any more devices
    jrnz    ci$next        ; go look at them
    pop    h        ; recover bit vector
    jr    in$scan        ; loop til we find a character

ci$rdy:
    pop    h        ; discard extra stack
    jmp    ?ci

    page

;    Utility Subroutines


?pmsg:                ; print message @<HL> up to a null
                ; saves <BC> & <DE>
    push    b
    push    d
pmsg$loop:
    mov    a,m
    ora    a
    jrz    pmsg$exit
    mov    c,a
    push    h
    call    ?cono
    pop    h
    inx    h
    jr    pmsg$loop
pmsg$exit:
    pop    d
    pop    b
    ret

?pdec:                ; print binary number 0-65535 from <HL>
    lxi    b,table10
    lxi    d,-10000
next:
    mvi    a,'0'-1
pdecl:
    push    h
    inr    a
    dad    d
    jrnc    stoploop
    inx    sp
    inx    sp
    jr    pdecl
stoploop:
    push    d
    push    b
    mov    c,a
    call    ?cono
    pop    b
    pop    d
nextdigit:
    pop    h
    ldax    b
    mov    e,a
    inx    b
    ldax    b
    mov    d,a
    inx    b
    mov    a,e
    ora    d
    jrnz    next
    ret

table10:
    dw    -1000,-100,-10,-1,0


?pderr:
    lxi    h,drive$msg
    call    ?pmsg            ; error header
    lda    @adrv
    adi    'A'
    mov    c,a
    call    ?cono            ; drive code
    lxi    h,track$msg
    call    ?pmsg            ; track header
    lhld    @trk
    call    ?pdec            ; track number
    lxi    h,sector$msg
    call    ?pmsg            ; sector header
    lhld    @sect
    jr    ?pdec            ; sector number (call/ret)


;
; BNKSEL
;    Bank Select.  Select CPU bank for further execution.
bnksel:
    sta    @cbnk             ; remember current bank
    jmp    ?bank            ; and go exit through users
                    ; physical bank select routine


xofflist:
    db    -1,-1,-1,-1,-1,-1,-1,-1        ; ctl-s clears to zero
    db    -1,-1,-1,-1,-1,-1,-1,-1



    dseg            ; following resides in banked memory



;    Disk I/O interface routines
;
; SELDSK
;    Select Disk Drive.  Drive code in <C>.
;        Invoke login procedure for drive
;        if this is first select.  Return
;        address of disk parameter header
;        in <HL>
seldsk:
    mov    a,c
    sta    @adrv            ; save drive select code
    mov    l,c
    mvi    h,0
    dad    h            ; create index from drive code
    lxi    b,@dtbl
    dad    b            ; get pointer to dispatch table
    mov    a,m
    inx    h
    mov    h,m
    mov    l,a            ; point at disk descriptor
    ora    h
    rz                 ; if no entry in table, no disk
    mov    a,e
    ani    1
    jrnz    not$first$select    ; examine login bit
    push    h
    xchg                ; put pointer in stack & <DE>
    lxi    h,-2
    dad    d
    mov    a,m
    sta    @RDRV            ; get relative drive
    lxi    h,-6
    dad    d            ; find LOGIN addr
    mov    a,m
    inx    h
    mov    h,m
    mov    l,a            ; get address of LOGIN routine
    call    ipchl            ; call LOGIN
    pop    h            ; recover DPH pointer
not$first$select:
    ret

    page
;
; HOME
;    Home selected drive.  Treated as SETTRK(0).
home:
    lxi    b,0            ; same as set track zero


;
; SETTRK
;    Set Track. Saves track address from <BC>
;        in @TRK for further operations.
settrk:
    mov    l,c
    mov    h,b
    shld    @trk
    ret


;
; SETSEC
;    Set Sector.  Saves sector number from <BC>
;        in @sect for further operations.
setsec:
    mov    l,c
    mov    h,b
    shld    @sect
    ret


;
; SETDMA
;    Set Disk Memory Address.  Saves DMA address
;        from <BC> in @DMA and sets @DBNK to @CBNK
;        so that further disk operations take place
;        in current bank.
setdma:
    mov    l,c
    mov    h,b
    shld    @dma
    lda    @cbnk        ; default DMA bank is current bank
                ; fall through to set DMA bank

;
; SETBNK
;    Set Disk Memory Bank.  Saves bank number
;        in @DBNK for future disk data
;        transfers.
setbnk:
    sta    @dbnk
    ret

    page
;
;
; SECTRN
;    Sector Translate.  Indexes skew table in <DE>
;        with sector in <BC>.  Returns physical sector
;        in <HL>.  If no skew table (<DE>=0) then
;        returns physical=logical.
sectrn:
    mov    l,c
    mov    h,b
    mov    a,d
    ora    e
    rz
    xchg
    dad    b
    mov    l,m
    mvi    h,0
    ret

    page
;
; READ
;    Read physical record from currently selected drive.
;        Finds address of proper read routine from
;        extended disk parameter header (XDPH).
read:
    lhld    @adrv
    mvi    h,0
    dad    h            ; get drive code and double it
    lxi    d,@dtbl
    dad    d            ; make address of table entry
    mov    a,m
    inx    h
    mov    h,m
    mov    l,a            ; fetch table entry
    push    h            ; save address of table
    lxi    d,-8
    dad    d            ; point to read routine address
    jr    rw$common        ; use common code


;
; WRITE
;    Write physical sector from currently selected drive.
;        Finds address of proper write routine from
;        extended disk parameter header (XDPH).
write:
    lhld    @adrv
    mvi    h,0
    dad    h            ; get drive code and double it
    lxi    d,@dtbl
    dad    d            ; make address of table entry
    mov    a,m
    inx    h
    mov    h,m
    mov    l,a            ; fetch table entry
    push    h            ; save address of table
    lxi    d,-10
    dad    d            ; point to write routine address

rw$common:
    mov    a,m
    inx    h
    mov    h,m
    mov    l,a            ; get address of routine
    pop    d            ; recover address of table
    dcx    d
    dcx    d            ; point to relative drive
    ldax    d
    sta    @rdrv            ; get relative drive code and post it
    inx    d
    inx    d            ; point to DPH again
ipchl:
    pchl                ; leap to driver

    page
;
; MULTIO
;    Set multiple sector count. Saves passed count in
;        @CNT
multio:
    sta    @cnt
    ret

;
; FLUSH
;    BIOS deblocking buffer flush.  Not implemented.
flush:
    xra    a
    ret                ; return with no error


;
; error message components
;
drive$msg:    db    cr,lf,bell,'BIOS Error on ',0
track$msg:    db    ': T-',0
sector$msg:    db    ', S-',0


    end