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- ::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::*
- *
- VERIFY function handler *
- *
- ----------------------------------------------------------------*
- *
- The verify function simply opens & then "reads" a file. *
- Actual verification occurs deep within RWTS. As the data are *
- read, a checksum is calculated. If the calculated checksum *
- agrees with the checksum byte read off the disk, the integrity *
- of the data are verified. Failure to verify yeilds an I/O *
- error. *
- *
- Execution pattern: *
- FNVERIFY ($AD18) first calls the common open routine *
- COMNOPEN ($AB28) to locate and then open the named file. *
- COMNOPEN configures the FM work area, reads in a fresh VTOC *
- and then searches the directory sectors for the file *
- description entry of the wanted file. (The links to the first *
- directory sector are stored as the 2nd and 3rd bytes (offsets *
- $01 and $02) of the VTOC. The 2nd and 3rd bytes of each *
- subsequent directory sector contain the trk and sec values of *
- the next directory sector. The link bytes of the last *
- directory sector are zeroed out.) *
- As each directory sector is read in, an attempt is made *
- to locate a file description which contains the name of the *
- file wanted. If the name can't be located after searching all *
- the directories and if the VERIFY command was used by itself, *
- a second search is made to locate the first available space in *
- a directory sector where a new file description can be placed *
- (in case the command can create a new file). If no free space *
- is located, a disk-full error message is printed. (When the *
- VERIFY command is accessed via the INIT, SAVE or BSAVE *
- commands, no second search is done because these previous *
- commands would have already created a new file entry if *
- necessary.) *
- If an available space is located, NWDESCRP ($B21C) copies *
- the name of the wanted file from the primary file name buffer *
- (PRIMFNBF, $AA75) into the new entry space. A check is then *
- made to see if the command can legally create a new file. The *
- identifying command byte (NDX2CMD, $AA5F) is used to index a *
- table of command attributes (CMDATTRB, $A909). Because bit 0 *
- of the first attribute byte associated with the VERIFY command *
- is clear, a new file cannot legally be created. As a result, *
- the VERIFY command is exited with a file-not-found message. *
- If a (non-deleted) description entry containing the name *
- of the wanted file is located, execution branches to the *
- FILLINWA routine ($ABA6). FILLINWA uses the information *
- contained in the description entry to customize the FM work *
- area. After the carry is cleared execution jumps to the *
- READTS routine ($AF5E). Because the carry was just cleared, *
- READTS reads in the file's first T/S list sector. *
- Execution then returns to the FNVERIFY routine at *
- VRFYREAD ($AD1B). VRFYREAD in turn calls NXTDATRD ($BOB6) to *
- read the file's data sectors into the data sector buffer. *
- The execution patterns associated with NXTDATRD and its *
- associated subroutines can be difficult to trace because so *
- many flags are envolved. Unfortunately these flags are an *
- evil necessity because NXTDATRD is called by almost any DOS *
- command that reads or writes disk data. A description of the *
- flags and possible execution patterns that can be taken by *
- NXTDTRD when called from the VERIFY command are shown below: *
- *
- Major decisions and flags used: *
- Use current data sector? *
- - yes = FILPTSEC/+1 = RELPREV/+1 *
- - no = FILPTSEC/+1 < > RELPREV/+1 *
- - when a file is first opened, the common open *
- routine (COMNOPEN, $AB28) sets FILPTSEC: $0000 *
- and RELPREV: $007A. This forces the computer *
- to try to use the file's first data sector. *
- - when a data sector is filled by successively *
- adding data byte, FILPTSEC/+1 > RELPREV/+1. *
- - if the position function was used to adjust *
- the filepointer out of the range of RELPREV, *
- then FILPTSEC/+1 < > RELPREV/+1. *
- Use current T/S list ? *
- - yes = FILPTSEC/+1 > RELFIRST/+1 *
- and FILPTSEC/+1 < RELASTP1/+1. *
- - no = FILPTSEC/+1 < RELFIRST/+1 *
- or FILPTSEC/+1 > = RELASTP1/+1. *
- Update current data or T/S list sectors? *
- - yes = bit 6 (data) or bit 7 (T/S list) of UPDATFLG *
- ($B5D5) are set. *
- - no = bits 6 and 7 of UPDATFLG are clear. *
- Read first T/S list? *
- - yes = (c) = 0 - carry cleared if file was just *
- opened. File pointer was previously *
- backed up by CALCFPTR ($B300). *
- - no = (c) = 1 - file is long enough that another T/S *
- list must be used. *
- Writing data? *
- - yes = OPCODEFM ($B105) = 4. *
- - no = OPCODEFM < > 4. *
- Any more data pairs listed in current T/S list? *
- - yes = trk byte portion of data pair < > $00. *
- - no = trk byte portion of data pair = $00. *
- Any more T/S lists in file? *
- - yes = trk byte portion of link < > $00. *
- - no = trk byte portion of link = $00. *
- (Link to first T/S list is contained in the first two *
- bytes of the file description entry in the directory sec. *
- Link to subsequent T/S lists are contained in 2nd and 3rd *
- bytes (offsets $01 and $02) of previous T/S lists.) *
- *
- Note: RELPREV ($B5E0, $B5E1) *
- = the relative sector number (in relation to *
- the entire file) of the last data sector that *
- was read or written. (Possible values are: *
- $0000, $007A, 2*$007A, 3*$007A, 4*$007A.) *
- RELFIRST ($B5DC, $B5DD) *
- = the relative sector number (in relation to *
- the entire file) of the first data sector *
- that is (or can be) listed in the current *
- T/S list. *
- RELASTP1 ($B5DE, $B5DF) *
- = one greater than the maximum relative sector *
- number (in relation to the entire file) of *
- the last data sector that can possibly be *
- listed in the current T/S list. (Possible *
- values are: $007A, 2*$007A, 3*$007A, 4*$007A *
- and 5*$007A.) *
- NXTDATRD execution patterns: *
- Pattern 1: = FILPTSEC/+1 = RELPREV/+1 *
- - select the current data sector. *
- - exit NXTDATRD routine via XITNXDAT. *
- Pattern 2: = FILPTSEC/+1 < > RELPREV/+1 *
- = FILPTSEC/+1 > = NDXFIRST/+1 *
- and FILPTSEC/+1 < RELASTP1/+1 *
- = trk portion of data pair < > 0 *
- - update the current data sector if necessary. *
- 2a: - get valid link byte to the next data sector from *
- the current T/S list. *
- - read in the next data sector. *
- - update RELPREV. *
- - exit the NXTDATRD routine via XITNXDAT. *
- Pattern 3: = FILPTSEC/+1 < > RELPREV/+1 *
- = FILPTSEC/+1 > = RELFIRST/+1 *
- and FILPTSEC/+1 < RELASTP1/+1 *
- = trk portion of data pair = 0 *
- = OPCODEFM < > 4 *
- - update the current data sector if necessary. *
- 3a: - detect zeroed out data pair in the current T/S *
- list. *
- - test OPCODEFM to determine that we are NOT *
- writing and set the carry flag to signal just *
- read all the data. *
- - exit the NXTDATRD routine via XITNXDAT. *
- Pattern 4: = FILPTSEC/+1 < > RELPREV/+1 *
- = FILPTSEC/+1 < = RELFIRST/+1 *
- = carry clear at $AF69 *
- = trk portion of link byte to next T/S list < > 0 *
- - update current data and/or T/S list secs if *
- necessary. *
- - get link to file's first T/S list from the file *
- description entry in the current directory sec. *
- - read in the first T/S list. *
- - loop back to do 2a, 3a or 5. *
- Pattern 5: = FILPTSEC/+1 < > RELPREV/+1 *
- = FILPTSEC/+1 > = RELASTP1/+1 *
- = carry set at $AF69 *
- = trk portion of link to next T/S list < > 0 *
- - update current data and/or current T/S list *
- sectors if necessary. *
- - get valid link bytes to the next T/S list from *
- the current T/S list. *
- - loop back to do 2a, 3a or repeat 5. *
- Pattern 6: = FILPTSEC/+1 < > RELPREV/+1 *
- = FILPTSEC/+1 > = RELASTP1/+1 *
- = carry set at $AF69 *
- = trk portion of link to next T/S list < > 0 *
- = OPCODEFM < > 4 *
- - update current data and/or current T/S list *
- sectors if necessary. *
- - get zeroed out link bytes to the next T/S list *
- from the current T/S list. *
- - test OPCODEFM to determine that we are NOT *
- writing and set the carry flag to signal that *
- we have just read all the data. *
- - exit NXTDATRD the routine via XITNXDAT. *
- *
- If no errors are encountered, the NXTDATRD routine *
- ($B0B6) is exited via XITNXDAT ($B12C). XITNXDAT points the *
- A4L pointer ($42, $43) at the DOS data sector buffer and sets *
- (y) to index that buffer. When an "RTS" is encountered, *
- execution returns to $AD1E in the VRFYREAD routine. *
- If this return is made with a set carry, all the data *
- have been read and the verify function is exited via a branch *
- to the TOOKFMXT ($AD0F). Otherwise, the file pointer is *
- incremented and execution jumps back to the VRFYREAD routine *
- ($AD1B) to "read" the next data sector. *
- *
- ----------------------------------------------------------------*
(AD18)
FNVERIFY JSR COMNOPEN ;Locate file with the same name and open it.
* Common open routine.
(AB28)
COMNOPEN JSR ZWRKAREA ;Initialize the work area.
* Zero out the FM work area so it can be customized
* in accordance with the calling function.
* (Although some work bytes may not be subsequently
* altered, don't be lulled into thinking that they
* are not important. Zero values can be just as relevant
* as non-zero values.)
* (P.S. Don't confuse FM work area with its image
* (FM work buffer) that is housed in the chain of
* DOS buffers.)
(ABDC)
ZWRKAREA LDA #0
TAX ;Initialize the x-index.
ZEROWRKA STA FMWKAREA,X ;Put a $00 byte in work area.
INX
CPX #45 ;Work area is 45 bytes long.
(ABE5) BNE ZEROWRKA
* Begin customizing the work area.
* Get volume, drive, slot & catalog track
* values from the FM parameter list. Put
* drive, slot*16, catalog track and
* complemented volume number in the work area.
(ABE7) LDA VOLFM ;Volume number.
EOR #$FF ;Calculate 1's complement of volume #.
STA VOLWA
LDA DRVFM ;Drive #.
STA DRVWA
LDA SLOTFM ;Get slot #.
ASL ;Calculate slot * 16.
ASL
ASL
ASL
TAX ;Set (x) = slot * 16.
STX SLOT16WA
LDA #$11 ;Normal catalog trk = #17.
STA TRKWA
(AC05) RTS
(AB2B) LDA #1 ;Describe sector length as 256 bytes
(AB2D) STA SECSIZWA+1 ;(in the FM work area).
* Get record length from the FM parameter
* list & put it in the FM work area.
* (Don't allow a zero length. If zero,
* change it to one.)
(AB30) LDX RECLENFM+1
LDA RECLENFM
BNE STRECLEN ;Non-zero record length is ok.
CPX #0
BNE STRECLEN
INX ;Was zero, make it one instead.
STRECLEN STA RECLENWA ;Put length in FM work area.
STX RECLENWA+1
(AB43) JSR GETFNTRY ;Try to find a directory sector for the file.
* Locate or create a file entry in the
* directory buffer.
* Make two searches if necessary:
* - Search1 - try to locate entry with same name as file wanted.
* - Search2 - couldn't locate entry corresponding to file
* wanted so create a new entry in first available
* space in the directory sector.
* Two searches are never required if the VERIFY cmd is
* accessed via the INIT, SAVE, or BSAVE commands.
* These calling commands would have previously
* created a new file description if necessary.
(B1C9)
GETFNTRY JSR READVTOC ;Read in the VTOC so we can get the link to
;TRKMAPS & to the first directory sector.
* Read the Volume Table of Contents (VTOC).
(AFF7)
READVTOC LDA #1 ;Read opcode for RWTS.
(AFF9) BNE RDWRVTOC ;ALWAYS.
* Code common to read/write VTOC.
(AFFD)
RDWRVTOC LDY ADRVTOC ;Get address of VTOC from the
STY IBBUFP ;FM constants table & designate it
LDY ADRVTOC+1 ;as the I/O buffer in RWTS's IOB.
STY IBBUFP+1
LDX TRKWA ;Enter RWTS driver with (x)/(y) equal
LDY #0 ;to the trk/sec values of the VTOC.
(B00E) JMP RWTSDRVR ;Call driver to read/write the VTOC.
------------
* Read/Write Track/Sector driver.
(B052)
RWTSDRVR .
.
(See dism'bly of RWTS driver using READ.)
.
.
(RTS)
* Point A4L/H at the primary file name buffer.
(B1CC) LDA FNAMBUFM ;Get address of the name buffer from the
STA A4L ;FM parameter list & put it in the A4L/H
LDA FNAMBUFM+1 ;pointer.
(B1D4) STA A4L+1
* Try to find the directory sector with the
* wanted file name & read it into the directory
* sector buffer. Make two searches if necessary.
* On the first search, try to find a matching name.
* If that doesn't work, do a second search to store
* the description in the first available file
* description field in a directory sector.
(B1D6) LDA #1 ;Initialize the search counter (SCRNSRCH)
SETSRCH STA SCRNSRCH ;in the FM scratch space for two searches.
(B1D8) ;(1 = search1, 0 = search2)
(B1DB) LDA #0 ;Initialize offset of file description from
STA SECNXDIR ;the very first directory sector.
CLC ;(c)=0=signal to read first directory sec.
GETDIRSC INC SECNXDIR ;Kick up offset from first directory.
(B1E1) ;(On first entry, $00 --> $01.)
(B1E4) JSR RDDIRECT ;Go read directory sector into buffer.
* Read a directory sector.
(B011)
RDDIRECT PHP ;Save (c) on stack:
; (c) = 0 = read 1rst directory sector.
; (c) = 1 = read next directory sector.
(B012) JSR PT2DIRBF
* Designate the directory sector buffer
* as I/O buffer in RWTS's IOB.
(B045)
PT2DIRBF LDA ADRDIRBF ;Get addr of direc
STA IBBUFP ;sec buf from the
LDA ADRDIRBF+1 ;FM constants tbl
STA IBBUFP+1 ;& designate it as
(B051) RTS ;as the I/O buffer.
(B015) PLP ;Check if 1rst directory sec or not.
(B016) BCS RDNXTDIR ;Go read next directory sector.
* Read the first directory sector.
* (Carry = 0.)
(B018)
RDFIRDIR LDY FIRDIRSC ;(y)/(x) = trk/sec vals of first directory
LDX FIRDIRTK ;sector (from the VTOC buffer).
(B01E) BNE DODIRRD ;ALWAYS - go read in directory sector.
* Read the next directory sector.
* (Carry = 1.)
(B020)
RDNXTDIR LDX DIRLNKTK ;Get track of next directory sec from the
;link in the current directory sector.
(B023) BNE GETDIRLK ;Link not zeroed out.
SEC ;Link zeroed out - exit with (c) = 1 to
(B026) RTS ;signal there are no more directory secs.
============
(B027)
GETDIRLK LDY DIRLNKSC ;Get sector of next directory sec from the
;link in the current directory sector.
* Call to read in the directory sector.
(B02A)
DODIRRD STX CURDIRTK ;Save trk/sec vals of directory sec that
(B02D) STY CURDIRSC ;we are about to read so they will be
;the current directory sec values for the
;next time around.
(B030) LDA #1 ;Read opcode for RWTS.
(B032) JSR RWTSDRVR ;Call RWTS driver to do the read.
* Read/Write Track/Sector driver.
(B052)
RWTSDRVR .
.
(See dis'mbly of RWTS driver using READ.)
.
.
(RTS)
(B035) CLC ;Link didn't zero out so signal that there
(B036) RTS ;are more directory secs to read & exit.
============
(B1E7) BCS CHNGSRCH ;Link zeroed out, no more directory secs,
;so go switch searches.
(B1E9) LDX #0
CKDIRTRK STX CURDIRNX ;Offset of file description into the current
(B1EB) ;directory sector.
(B1EE) LDA FIL1TSTK,X ;Get track number of first T/S list
;for a particular file from the file
;description entry in the directory sector.
(B1F1) BEQ CHRSRCHA ;If trk=0, no more files in this direc sec.
(B1F3) BMI CHRSRCHB ;Skip deleted file. (When a file is
;deleted, #$FF is put in byte where trk #
;of first T/S list is usually kept.
* Compare the name found in the file
* description entry portion of the
* directory sector with the file name
* wanted. (On entry, A4L/H points at
* the primary file name buffer.)
(B1F5) LDY #0 ;Initialize index to file name buffer.
INX ;Point (x) at the first char position
INX ;in the name field of description entry.
CMPNAMES INX
LDA (A4L),Y ;Get char of name from primary.
CMP FIL1TSTRK,X ;Compare to char in name of description.
BNE DONTMTCH ;Chars (and therefore names) don't match.
INY
CPY #30 ;Done all chars yet (0 to 29)?
BNE CMPNAMES ;Chars matched, branch if more to check.
LDX CURDIRNX ;All chars matched, so names matched.
CLC ;Return with (x) = index to file
(B20A) RTS ;description in current directory sector
============ ;and with (c) = 0 to signal that the
;correct file description was found.
* Advance index to point at the next
* potential file description entry.
(B20B)
DONTMTCH JSR NXPLUS35 ;Names didn't match, so adjust index
;to point at the next entry.
* Add 35 to the offset to point the index
* at the next file description entry.
* (Check to make sure that we don't index
* right off the end of the directory sec.)
(B230)
NXPLUS35 CLC
LDA CURDIRNX
(B234) ADC #35 ;Add 35 to index. (Each file description
;entry is 35 bytes long.)
(B236) TAX ;Check if there is more space for entries
CPX #245 ;in the current directory sector.
(B239) RTS ;Exit with (c) conditioned:
; (c) = 0 = more space in directory.
; (c) = 1 = ran off end of directory.
(B20E) BCC CKDIRTRK ;More potential file descriptions to check
;in this directory sector.
(B210) BCS GETDIRSC ;Go get next directory sector.
------------
* If we just completed the first seach,
* go back to do the second search.
(B212)
CHRSRCHA LDY SCRNSRCH ;(1 = search1, 0 = search2)
(B215) BNE SETSRCH ;Go switch to second search.
* If first search, skip deleted files.
* If second search, fall through to store
* the description in the first unused
* space in the directory.
(B217)
CHRSRCHB LDY SCRNSRCH ;(1 = search1, 0 = search2)
(B21A) BNE DONTMTCH
* Couldn't locate the named file in the
* directory description entries, so begin
* creating a new description in the first available
* space in a directory (in case command can
* legally create a new file).
(B21C)
NWDESCRP LDY #0 ;Initialize index to primary file name buffer.
INX ;Set index to first char position in the
INX ;name field of the file description entry
SETNWNAM INX ;space in the directory sector.
LDA (A4L),Y ;Copy char from primary file name buffer
STA FIL1TSTK,X ;to the directory description space.
INY
CPY #30 ;30 chars in name (0 to 29).
BNE SETNWNAM ;Branch if more chars to copy.
LDX CURDIRNX ;Return with (x) = index to file
SEC ;description space in current directory
(B22F) RTS ;sector & with (c)=1 to signal new entry
============ ;was just created.
* If first search, switch to second search.
* If second search, link zeroed out because
* there isn't enough room left on the
* disk for a new entry. Therefore,
* exit with a disk-full error message.
(B23A)
CHNGSRCH LDA #0 ;Used to reset search counter if
;we go back to start a second search.
(B23C) LDY SCRNSRCH ;(1 = search1, 0 = search2)
BNE SETSRCH ;Just did search1 so go start search2.
(B241) JMP DISKFULL ;Even second search was unsuccesful
------------ ;so go handle a disk-full error.
(AB46) BCC FILLINWA ;Branch if found a directory sector with
;name wanted in the file description entry.
;Will always find name if using verify in association
;with INIT, SAVE or BSAVE commands because these commands
;would have previously provided a new name if necessary.
* Named file wasn't found in directory,
* so prepare a new file entry in case
* command can legally create a new file.
(AB48) STX CURDIRNX ;Offset to new description entry in
;case want to create a new file.
* Check to see if command can
* legally create a new file.
(AB4B) LDX NDX2CMD ;(x) = index representing command.
(AB4E) LDA CMDATTRB,X ;Get first byte containing description
;of the given command's attributes.
(AB51) LDX CURDIRNX ;(x) = index for new file description
;entry into the directory sector.
(AB54) LSR ;(c) = bit 0 of 1rst attribute byte.
(AB55) BCS CREATNEW ;If (c) = 1, command can create a new file.
;ALWAYS FALL THRU WHEN VERIFYING.
* Command can't create a new file.
* See which language we are using and
* exit with the appropriate error msg.
(AB57)
NEWILLGL LDA CONDNFLG ;$00=warmstart, $01=reading, $40=A(RAM),
;$80=coldstart & $C0=integer.
(AB5A) CMP #$C0 ;Integer in ROM?
BNE TOFILNOT ;No.
(AB5E) JMP LNGNOTAV ;Yes - handle language-not-available error.
------------
TOFILNOT JMP FILENOT ;Handle file-not-found error.
(AB61) ------------
* Fill in the FM work area buffer.
* (Routine common to opening a new
* or pre-existing file.)
(ABA6)
FILLINWA LDA FIL1TSTK,X ;T/S list trk val (from directory sec).
STA FIRSTSTK
LDA FIL1TSSC,X ;T/S list sec val (from directory sec).
STA FIRTSSEC
LDA FIL1TYPE,X ;File type (from directory sec).
STA FILTYPFM
STA FILTYPWA
LDA FIL1SIZE,X ;File size (from directory sec).
STA FILENSEC
LDA FIL1SIZE+1,X
STA FILENSEC+1
STX BYTNXDIR ;Index into directory sec to description.
LDA #$FF ;Pretend that the last data sector used had
STA RELPREV ;a relative sector number (in relation to
(ABCF) STA RELPREV+1 ;the entire file) of $FFFF. NOTE: This
;value is later used to trick the read and
;write subfunctions into ignoring the data
;sector currently in memory.
(ABD2) LDA MXIN1TSL ;Dicatate that a T/S list can only describe $7A
(ABD5) STA MXSCURTS ;(#122) data sectors. Note: This value is later
;used by the read and write subfunctions to decide
;whether or not the T/S list currently in memory
;should be used.
* Read first T/S list sector
* to the T/S list buffer.
(ABD8) CLC ;(c) = 0 = signal 1rst T/S list sector.
(ABD9) JMP READTS ;Go read in the T/S list sector.
------------
* Read T/S list sector.
(AF5E)
READTS .
.
(See dis'mbly given below.)
.
.
(RTS)
(AD1B)
VRFYREAD JSR NXTDATRD ;Read the next data sector in. (Assume
;the data sector we want is not presently
;in memory.)
* Check if we need to read the next data
* sector into the data sector buffer.
*
* - Is the data sec we want already in memory?
* - If so, does it require updating?
* If sector offset into file (FILPTSEC) equals
* the relative sector number of the last sector
* read or written (RELPREV), then sector we want
* is presently in memory. If it is not in memory,
* read in the data sector wanted. However, first
* check if the data sector has changed since the
* last read or write. If it has, the disk must
* be updated before we read in the new data
* sector so we don't overwrite the data
* sector buffer and loose information.
* NOTE: - if this subroutine is called from a
* write subfunction and FILPTSEC is not
* equal to RELPREV, then the data sector
* buffer must be full & therefore should
* be written to the disk before any more
* information is read in.
* - if the file was just opened, the open
* subfunction set FILPTSEC = $0000 and
* RELPREV = #$FFFF so always force reading
* of a new data sector even if the correct
* sector is already in memory.
* NOTE: Not all of the NXTDATRD routine is listed
* because not all of it applies to the
* VERIFY function.
(B0B6)
NXTDATRD LDA FILPTSEC ;Last sector used versus sector wanted?
CMP RELPREV
(B0BC) BNE CKWCURDA ;Not same - will eventually have to read in
;a new data sector.
;Note: THIS BRANCH IS ALWAYS TAKEN ON FIRST
; ENTRY FROM THE VERIFY FUNCTION
; because RELPREV was set to #$FFFF
; in the FILLINWA section of the
; common open routine. In other
; words, program flow in the VERIFY
; function is such that a new data
; read is forced even if the correct
; data sector is already resident in
; the data sector buffer.
(B0BE) LDA FILPTSEC+1 ;Maybe same - check hi bytes.
CMP RELPREV+1
(B0C4) BEQ XITNXDAT ;Same, so go exit.
* Write the data sector if necessary.
* Data sector we want is not presently
* in memory. Check if we need to write
* the current data sector buffer before
* we read in the wanted data sector.
(B0C6)
CKWCURDA JSR CKDATUP ;Check the update flag to see if the data
;sector buffer has changed since the last
;read or write. If it has, write the data
;sector buffer to the disk.
* Check if the data sector has changed
* since the last read or write was done.
(AF1D)
CKDATUP BIT UPDATFLG ;Check bit 6 to see if data sec requires
;updating or not.
(AF20) BVS WRITDATA ;Take branch if data requires updating.
;ALWAYS FALL THRU WHEN USING VERIFY.
(AF22) RTS
* Should current T/S list be used?
* (That is, should the data sector be listed in
* the present T/S list sector? If not, then
* will need to read in the correct T/S list.)
* Is the sector offset into the file of the present
* data sector less than the relative sector number
* of the FIRST data sector that can be described in
* the T/S list presently in memory? (If less,
* then need to read in a different T/S list sector.)
(B0C9)
CKCURTS LDA FILPTSEC+1 ;Sector offset in file associated with
(B0CC) CMP RELFIRST+1 ;the present data sector versus the
;relative sector number of the first data
;sector that can be described in the present
;T/S list.
(B0CF) BCC NEEDNXTS ;Data sector wanted represents a SMALLER offset
;into the file so need a different T/S list.
(B0D1) BNE CKCURTS1 ;Sector offset of wanted data sector is
;LARGER than that of the first data sector that
;can be described in the present T/S list so it
;may still belong to this T/S list.
(B0D3) LDA FILPTSEC ;Hi bytes same - so compare low bytes.
CMP RELFIRST
(B0D9) BCC NEEDNXTS ;Sector offset of wanted files is LESS,
;so read in a different T/S list.
;(Start by reading the file's first T/S list.)
* Sector offset associated with the data
* sector we want is either GREATER THAN OR
* EQUAL TO the relative sector offset
* associated with the first data sector that can
* be described in this T/S list. Therefore,
* compare the sector offset of the sector
* wanted with the relative sector number
* (plus 1) of the LAST sector that can be
* described in the present T/S list.
(B0DB)
CKCURTS1 LDA FILPTSEC+1 ;Sector offset associated with data sector
(B0DE) CMP RELASTP1+1 ;we want versus the relative sector number
;(plus 1) of the LAST data sector that can possibly
;be described in the present T/S list.
(B0E1) BCC GETDATPR ;Sector offset assoc with data sector we
;wanted IS described in the present T/S list.
(B0E3) BNE NEEDNXTS ;Sector offset of present data sector is
;LARGER than that of the LAST data sector
;(plus 1) that can possibly be described in the
;present T/S list, so we need a new T/S list sector.
(B0E5) LDA FILPTSEC ;Hi bytes same - so compare low bytes.
CMP RELASTP1
(B0EB) BCC GETDATPR ;Sector offset associated with data sector
;we want is LESS than the relative sector
;number (plus 1) of the last data sector that
;can possibly be listed in the present T/S list.
;There4, data sector wanted should be described
;in the present T/S list.
* The data sector we want is NOT listed
* in the present T/S list, so we must
* read a different T/S list sector.
* (NOTE: Routine is entered with (c) = 1 if need a
* higher numbered T/S list. If (c) = 0, then the file
* pointer was backed up and we need a smaller numbered
* T/S list.)
(B0ED)
NEEDNXTS JSR READTS ;Read in the next (or first) T/S list. However,
;first check the update flag to see if the T/S list
;presently in memory requires updating before
;we read in the next (or first) T/S list sector.
;If updating is required, write the present
;T/S list.
* Read T/S list sector.
(AF5E)
READTS PHP ;Save (c) denoting if 1rst T/S list or not.
;(c) = 0 = read 1rst T/S list sec.
;(c) = 1 = read next T/S list sec.
(AF5F) JSR CKTSUPDT ;Write T/S list sec buf if updating is
;required. (If T/S list buf has changed
;since last read or write, then write it
;back to the disk so don't overwrite buf
;and lose information when read the new
;T/S list sector.)
* Check if T/S list requires updating.
* (ie. Has T/S list buf changed since
* the last read or write?)
(AF34)
CKTSUPDT LDA UPDATFLG
(AF36) BMI WRITETS ;If bit 7 set, updating is required.
;ALWAYS FALL THRU FOR VERIFY FUNCTION.
(AF37) RTS
============
(AF62) JSR SETTSIOB ;Prepare RWTS's IOB for READING a T/S list.
* Prepare RWTS's IOB for reading
* or writing the T/S list sector.
(AF4B)
SETTSIOB LDA TSBUFFM ;Get adr of the T/S list buf from the FM
STA IBBUFP ;parameter list & designate T/S list buf
LDA TSBUFFM+1 ;as the I/O buffer in RWTS's IOB.
STA IBBUFP+1
LDX CURTSTRK ;Set (x)/(y) = trk/sec of current T/S list.
LDY CURTSSEC
(AF5D) RTS
(AF65) JSR SELTSBUF ;Select the T/S list buffer.
* Point A4L/H at the T/S list sector buffer.
(AF0C)
SELTSBUF LDX #2 ;Index for T/S list buf.
(AF0E) BNE PT2FMBUF ;ALWAYS.
(AF12)
PT2FMBUF LDA WRKBUFFM,X ;Get address of the desired buffer from
STA A4L ;the FM parameter list & put it in the
LDA WRKBUFFM+1,X ;A4L/H pointer.
STA A4L+1
(AF1C) RTS
(AF68) PLP ;Get saved (c) back from stack.
(AF69) BCS RDNXTTS ;If (c) = 1, already read first T/S list
;sec, so go read next one.
* Read first T/S list sector.
* (Carry was clear.)
(AF6B)
RDFIRSTS LDX FIRSTSTK ;Set (x)/(y)=trk/sec of first T/S list sec.
LDY FIRTSSEC
(AF71) JMP RDTSLST ;Go read T/S list sector into buffer.
------------
* Read next T/S list sector.
* (Carry was set.)
(AF74)
RDNXTTS LDY #1 ;Index into T/S list buffer.
LDA (A4L),Y ;Trk for link to next T/S list sector.
(AF78) BEQ TSLNKZRO ;Link zeroed out, so there are no more
;T/S list sectors for file.
(AF7A) TAX ;(x) = next T/S list trk.
INY
LDA (A4L),Y ;Sector for link to next T/S list sector.
TAY ;(y) = next T/S list sector.
(AF7F) JMP RDTSLST ;Go read in next T/S list sector.
------------
* T/S link zeroed out so now must
* decide if got an error or not.
(AF82)
TSLNKZRO LDA OPCODEFM ;Check read/write status to see if want to
CMP #4 ;add another T/S list or not.
BEQ UPDATETS ;Writing, so go update link.
(AF89) SEC ;Set (c) = 1 to signal no more data.
;(Causes out-of-data error when reading.
;Signals verification completed when verifying.)
(AF8A) RTS
=========
* Subroutine to read T/S list sector.
(AFB5)
RDTSLST LDA #1 ;READ opcode for RWTS.
* Code common to read/write T/S list.
(AFB7)
RDWRTS STX CURTSTRK ;New T/S list sector trk/sec values (x)/(y)
STY CURTSSEC ;become current T/S list trk/sec values.
(AFBD) JSR RWTSDRVR ;Call RWTS driver to read/write current T/S
;list.
* Read or write the current T/S list.
(B052)
RWTSDRVR .
.
(See dis'mbly of RWTS driver using READ or WRITE.)
.
.
(RTS)
* Update the FM work area
* (not in DOS buffer chain).
(AFC0) LDY #5 ;Offset into current T/S list buffer.
LDA (A4L),Y ;Get & save the relative sector number of
(AFC4) STA RELFIRST ;the first data sector that can be
;described in this T/S list. (Possible
;values are: $0000, $007A, 2*$007A,
;3*$007A or 4*$007A.)
(AFC7) CLC ;Add the maximum number of secs that
ADC MXSCURTS ;can be described in this T/S list.
(AFCB) STA RELASTP1 ;Store the maximum relative sector number
;(plus 1) that can possibly be described
;in this particular T/S list. (That is,
;reset RELASTP1.)
(AFCE) INY
LDA (A4L),Y
STA RELFIRST+1
ADC MXSCURTS+1
STA RELASTP1+1 ;Value equals $0000, $007A
CLC ;2*$007A, 3*$007A, 4*$007A or 5*$007A.
(AFDB) RTS
============
(B0F0) BCC CKCURTS ;Go back and check if this is
;the correct T/S list.
(B0F2) RTS ;RETURN WITH (c)=1 TO SIGNAL RAN OUT OF DATA.
============
* We know that the data sector wanted
* should be described in the present T/S
* list so now calculate the offset into
* the T/S list sector where the data
* sector pair should be described.
(B0F3)
GETDATPR SEC ;Calculate offset to the data pair:
LDA FILPTSEC ; Sector offset of data sector into file
(B0F7) SBC RELFIRST ; minus the relative index of first data
; sector pair described in present T/S list.
(B0FA) ASL ;Times 2, cause 2 bytes used to describe a data pair.
ADC #12 ;Add 12 cause 1rst data pair is always listed
TAY ;12 bytes from the start of the T/S list buf.
(B0FE) JSR SELTSBUF ;Point A4L/H at the T/S list buffer.
* Point the A4L/H pointer at the
* T/S list sector buffer.
(AF0C)
SELTSBUF LDX #2 ;Index to select T/S list sector buffer.
(AF0E) BNE PT2FMBUF ;ALWAYS.
(AF12)
PT2FMBUF LDA WRKBUFFM,X ;Get address of selected buffer from
STA A4L ;the FM parm list & put it in the pointer.
LDA WRKBUFFM+1,X
STA A4L+1
(AF1C) RTS
(B101) LDA (A4L),Y ;Get trk number part of data sector pair.
(B103) BNE RDDATSEC ;Go read in the data sector.
* The track number part of the data sector
* pair listed in the T/S list was zero.
* Therefore, there are no more data sector
* pairs described in this T/S list.
(B105) LDA OPCODEFM ;Check to see if writing or not.
CMP #4 ;Opcode for write.
BEQ NEWPAIR ;Branch if writing.
SEC ;Not writing and ran out of data sector pairs
(B10D) RTS ;in the present T/S list, so go exit with
============ ;carry set to signal no more data.
* The data sector pair associated with the
* data sector wanted was contained in the
* current T/S list, so now read in the data
* sector wanted.
(B114)
RDDATSEC STA CURDATRK ;Save trk/sec values of current data sector
INY ;in the work area.
LDA (A4),Y ;Sector number of current data sector.
STA CURDATSEC
(B11D) JSR READDATA ;Go read in the data sector.
* Read data sector from disk
* to the data sector buffer.
(AFDC)
READDATA JSR PRPDAIOB ;Set up RWTS's IOB to read a data sector.
* Prepare RWTS'S IOB to read/write
* the data sector.
(AFE4)
PRPDAIOB LDY DATBUFFM ;Get the addr of the
LDA DATBUFFM+1 ;data sec buf from
STY IBBUFP ;the FM parm list and
(AFED) STA IBBUFP+1 ;designate it as the I/O
;buffer for RWTS's IOB.
(AFF0) LDX CURDATRK ;Enter RWTS driver with (x)/(y)
LDY CURDATSC ;= trk/sec vals corresponding
(AFF6) RTS ;to the data sector.
(AFDF) LDA #1 ;Opcode for RWTS's read command.
(AFE1) JMP RWTSDRVR ;Call RWTS driver to read the data sec buf.
------------
* Read/Write Track/Sector driver.
(B052)
RWTSDRVR .
.
(See dis'mbly of RWTSDRVR using READ.)
.
.
(RTS)
* Save sector-offset-into-file value
* associated with the data sector just read.
(B120)
SETPREV LDA FILPTSEC ;Current sector offset into file.
STA RELPREV ;Offset into file of last data sector read.
LDA FILPTSEC+1
(B129) STA RELPREV+1
* Exit the read-next-data-sector routine.
(B12C)
XITNXDAT JSR SELDABUF ;Select the data sector buffer.
* Point A4L/H at the data sector buffer.
(AF10)
SELDABUF LDX #4 ;Index to select data sector buffer.
PT2FMBUF LDA WRKBUFFM,X ;Get address of selected buffer from
STA A4L ;the FM parameter list & put it in the
LDA WRKBUFFM+1,X ;A4L/H pointer.
STA A4L+1
(AF1C) RTS
(B12F) LDY FILPTBYT ;(y) = offset into current data sector.
CLC ;Exit cleanly.
(B133) RTS
============
(AD1E) BCS TOOKFMXT ;END OF FILE DETECTED - exit file manager.
INC FILPTSEC ;Kick up the file pointer position and then
BNE VRFYREAD ;go back to read in the next data sector
INC FILPTSEC+1 ;until an end-of-file marker is detected.
(AD28) JMP VRFYREAD
-------------
(AD0F)
TOOKFMXT JMP GOODFMXT ;Exit the file manager cleanly.
------------
- Exit the file manager with or without errors.
(B35F)
LNGNOTAV LDA #1
(B361) BNE BADFMXIT ;ALWAYS.
(B373)
FILENOT LDA #6
(B375) BNE BADFMXIT ;ALWAYS.
(B377)
DISKFULL JMP FULLPTCH ;(See dis'mbly of errors.)
------------
(B37F)
GOODFMXT LDA RTNCODFM
CLC ;(c) = 0 to signal good operation.
BCC FMEXIT
BADFMXIT SEC ;(c) = 1 to signal unsuccessful.
FMEXIT PHP ;Save status on stack.
STA RTNCODFM ;Store return code in FM parameter list.
LDA #0
STA STATUS
(B38E) JSR CPYFMWA ;Copy the work area to the work buffer.
* Copy the FM work area (non-chain) to
* the FM work buffer (in DOS chain).
(AE7E)
CPYFMWA JSR SELWKBUF ;Select the FM work buffer (in DOS chain).
* Point the A4L/H pointer at the FM work buffer.
(AF08)
SELWKBUF LDX #0 ;Set index to select work buffer.
(AF0A) BEQ PT2FMBUF ;ALWAYS.
(AF12)
PT2FMBUF LDA WRKBUFFM,X ;Get address of selected buffer from the
STA A4L ;FM parameter list & put it in the pointer.
LDA WRKBUFFM+1,X
STA A4L+1
(AF1C) RTS
(AE81) LDY #0 ;Initialize index.
STORWRK LDA FMWKAREA,Y ;Get byte from the FM work area.
STA (A4L),Y ;Put it in the work buffer.
INY
CPY #45 ;45 bytes to copy (0 to 44).
BNE STORWRK
(AE8D) RTS
(B391) PLP ;Retrieve status of success of operation
;from the stack.
(B392) LDX STKSAV ;Adjust stack pointer to force exit to the
TXS ;caller of the function (even if we are
(B396) RTS ;presently several subroutines deeper than
============ ;the original entry point). (Returns to
;AFTRFUNC ($A6AB) in the FMDRIVER routine
;($A6A8).)