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-=-=-=-=-=-=-
- *****************************************************************
- *
- OPEN Command Handler *
- *
- ----------------------------------------------------------------*
- *
- The OPEN command prepares a new or pre-existing text file *
- for subsequent reading or writing. A file is considered to be *
- opened once it has been assigned a DOS buffer and its first *
- T/S list sector has been read. *
- *
- The OPEN command can only be issued from the deferred *
- mode. A file name must be issued with the command. Volume, *
- drive, slot and record length parameters are optional. If a *
- record length (L-parameter) is not not issued with the command *
- or if an L-value of zero is used, the record length is *
- automatically set to a default value of one. Sequential text *
- files have a record length of one whereas random access text *
- files use a record length between $02 and $7FFF (decimal 2 to *
- 32767). Both kinds of text files use the same file type code *
- ($80=locked, $00=unlocked). *
- *
- Execution pattern: *
- After the code for a text file ($00) is stored in the FM *
- parameter list (at FILTYPFM, $B5C2) and saved on the stack, *
- the common file manager command handler code (HNDLCMD, $A2A8) *
- is called. HNDLCMD first stores the open opcode ($01) and *
- then sets the record length. If an L-parameter of zero was *
- given or if no L-parameter was issued with the command, the *
- record length is set to a default value of one. CMDCLOSE *
- ($A2EA) is then called to close the file if it is already *
- open. Next a DOS buffer is (re)assigned to the named file and *
- the FM parameter list is customized. The file manager *
- (FILEMGR, $A6AB) is then called to do the open function *
- (FNOPEN, $AB22). *
- FNOPEN calls the common open routine (COMNOPEN, $AB28) to *
- configure the FM work area and search the directory sectors for*
- the name of the file wanted. The directory sectors are read *
- one at a time until a file description entry is located which *
- contains the name of the file wanted. If a matching file name *
- cannot be found, the directory sectors are seached again. This*
- second search is used to locate a space for a new file *
- description in case the command can legally create a new file. *
- If the second search fails to locate an available space, a *
- disk-full error message is printed. *
- Upon finding a free space, NEWDSCRP ($B21C) copies the *
- file name from the primary file name buffer (PRIMFNBF, $AA75) *
- into the new description entry space. Next, the cmd attribute *
- table (CMDATTRB, $A909) is checked to confirm that the open *
- command can legally create a new file. CREATENEW ($AB64) is *
- then called to create the new file: *
- - The file size bytes in the description entry are *
- initialized to describe a one-sector long file. *
- - ASGNTKSC ($B244) is called to locate a free sector *
- for the new T/S list. Once an available sector is *
- located, the entire track is assigned in the VTOC *
- buffer and the VTOC is updated on the disk. *
- - The trk/sec values of the new T/S list and the file *
- type code are stored in the description entry. *
- - The directory sector containing the new file *
- description is written to the disk. *
- - Finally, the T/S list buffer is zeroed out and written *
- as the first T/S list sector for the new file. *
- After creating a new file or locating an old file, the *
- FNOPEN routine reads in the file's first T/S list and exits *
- back into the open command handler. The file type of the pre- *
- existing or newly created file is then compared to the file *
- type wanted. If a match occurs, the open command is exited. *
- Otherwise, the open command is negated when the file is closed *
- and a file-type-mismatch error messaage is printed. *
- *
- Note that when a new file is opened, only one sector is *
- actually assigned to the file yet an entire track is allocated *
- in the VTOC. This contradiction is reconcilled when a file is *
- closed. The close command frees up any sectors that were *
- assigned but not used by the file. Therefore, if you happen *
- to hit the reset key or turn the computer off before a file is *
- closed, the disk may be left with several allocated but unused *
- sectors. This wasted disk space can only be recovered with a *
- disk repair program or by manually updating the VTOC as *
- follows: *
- - Catalog the disk *
- - Enter the monitor (type: CALL -151 <rtn>) *
- - Correct the offending TRKMAP bytes (see description *
- of the VTOC given in the linear disassembly. *
- - Update the VTOC on the disk (type: AFFBG <rtn>). *
- A file must be at least two sectors long (one T/S list *
- sector and one data sector) to be useful. Therefore, if you *
- encounter a catalog which describes a one-sector long file, *
- you can be sure that (a) the file size bytes in the description*
- entry were zapped, (b) the file is 257 sectors long (001 in *
- 256 modulus format) or (c) a new file was opened but never *
- closed. *
- *
- *****************************************************************
- On entry - CUMLOPTN ($AA65) has been updated
- to reflect parsed option words.
- - the validity of the options issued
- with the command (and their numeric
- values) have been checked.
- - a legal file name has been parsed and
- stored in the primary file name buffer
- (PRIMFNBF, $AA75).
- - confirmation has been made that the
- computer is working in the deferred mode.
(A2A3)
CMDOPEN LDA #0 ;0 = code for text file.
(A2A5) JMP OPNCKTYP ;Go open the file & chk its type.
------------
(A3D5)
OPNCKTYP STA FILTYPFM ;Put code for file type in the
(A3D8) PHA ;Fm parameter list & save it on stk.
;($00=Text, $01=Integer, $02=Applesoft,
;$04=Binary, $08=S-type, $10=Relocatable,
;$20=A-type and $40=B-type.)
(A3D9) JSR HNDLCMD ;Use FM cmd handler to open file.
* Common file manager command handler code.
(A2A8)
HNDLCMD LDA #1 ;1 = open opcode.
HNDLCMD1 STA TEMPBYT ;Store opcode in temporary location.
LDA LENPRSD ;Get L-parameter from parsed table.
BNE SAVLENFM ;Was a non-zero L-parm issued with cmd?
LDA LENPRSD+1
BNE SAVLENFM
LDA #1 ;Length was 0 so make it 1 instead.
STA LENPRSD
SAVLENFM LDA LENPRSD ;Put length in FM parm list.
STA RECLENFM ;(Note: Record length = 1 for sequential files
LDA LENPRSD+1 ;else parsed length for random access files.)
STA RECLENFM+1
CLSLOCBF JSR CMDCLOSE ;Close file if it's already open.
(A2C8)
(A2EA)
CMDCLOSE .
.
(See dis'mbly of CMDCLOSE given below.)
.
.
- Note that execution flows thru CMDCLOSE twice if the
file is already open.
- The first time thru, the matching DOS filename buffer is
located & then CLOSEONE is used to close the file.
- Execution then jumps back to the start of CMDCLOSE.
- On this second pass, a matching filename is not found
because the DOS filename buffer was released on the
first pass. Therefore, A5L/H is left pointing at the
highest numbered (lowest in memory) FREE DOS buffer
when CMCLOSE is exited via EVENTXIT and CLOSERTS.
- If the file is not already open on the first entry to
CMDCLOSE, only one pass is made. This single pass
resembles the second pass mentioned above.
.
.
- If necessary, the CLOSE FUNCTION updates the data
sector, T/S list sector & the VTOC. It also fixes
up links in the directory sectors and updates the
file size if needed.
.
.
(RTS)
(A2CB) LDA A5L+1 ;Hi byte of A5L/H pointer which points at the highest
;numbered (lowest in memory) free DOS name buffer (in chain).
(A2CD) BNE SAVFNPTR ;Branch if found a free buffer.
(A2CF) JMP NOBUFERR ;Go issue an out-of-buffers message.
------------ ;(See dis'mbly of errors.)
(A2D2)
SAVFNPTR STA A3L+1 ;Reset A3L/H to point at DOS buffer that we
LDA A5L ;will use for file name field buffer (chain).
STA A3L
(A2D8) JSR CPYPFN
* NOTE: This (re)assigns a DOS buffer to the
* file we want to open. The buffer may or may not
* be the same one that was just released by the CLOSE
* command above. The highest numbered (lowest in
* in memory) free DOS buffer is used.
(A743)
CPYPFN LDY #29 ;30 bytes to copy (0 to 29).
CPYPRIM LDA PRIMFNBF,Y ;Copy the name of the file wanted from
STA (A3L),Y ;the primary filename buffer into the
DEY ;filename field buffer (in DOS chain).
BPL CPYRIM ;More chars to get.
(A74D) RTS
(A2DB) JSR BUFS2PRM
* Get addresses of the various DOS buffers from the
* chain buffer & put them in the FM parameter list.
(A74E)
BUFS2PRM LDY #30 ;Get addr of FM work buf, T/S list
ADRINPRM LDA (A3L),Y ;buf, data sector buf & next DOS
STA WRKBUFFM-30,Y ;filename buf from chain
INY ;pointer buffer & put them in FM parm list.
CPY #38 ;(P.S. Adr of next DOS file name buf is
BNE ADRINPRM ;not used by DOS.)
(A75A) RTS
(A2DE) JSR CPY2PARM
* Put volume, drive, & slot values plus the
* address of the primary filename buffer
* in the FM parameter list.
(A71A)
CPY2PARM LDA VOLPRSD ;From parsed table.
STA VOLFM
LDA DRVPRSD ;From parsed table.
STA DRVFM
LDA SLOTPRSD ;From parsed table.
STA SLOTFM
LDA ADRPFNBF ;Get the adr of the primary file
STA FNAMBUFM ;name buf from the constants tbl
LDA ADRPFNBF+1 ;and put it in the FM parm list.
STA FNAMBUFM+1
LDA A3L ;Save adr of current DOS file name
STA CURFNADR ;buf in table of DOS variables.
LDA A3L+1
STA CURFNADR+1
(A742) RTS
(A2E1) LDA TEMPBYT ;Get open opcode back from temporary buffer
STA OPCODEFM ;and put it in the FM parameter list.
(A2E7) JMP FMDRIVER ;Do function via the FM driver.
------------
* Use the file manager driver
* to do the OPEN FUNCTION.
(A6A8)
FMDRIVER JSR FILEMGR ;Call the file manager to do the function.
* File manager proper.
(AB06)
FILEMGR TSX ;Save stk pointer so can later rtn to the
(AB07) STX STKSAV ;caller of the file manager. (That is, set it
;to return to the AFTRFUNC routine ($A6AB).)
(AB0A) JSR RSTRFMWA
* Copy FM work buf (in DOS chain) to
* FM work area (not in DOS chain).
(AE6A)
RSTRFMWA JSR SELWKBUF ;Point A4L/H at FM work buf.
* Get addr of FM work buff from
* the FM parm list & put it in
* the A4L/H pointer.
(AF08)
SELWKBUF LDX #0 ;Offset to select
;work buffer.
(AF0A) BEQ PT2FMBUF ;ALWAYS.
(AF12)
PT2FMBUF LDA WRKBUFFM,X
STA A4L
LDA WRKBUFFM+1,X
STA A4L+1
(AF1C) RTS
(AE6D) LDY #0 ;Zero out return code in FM parm list to
STY RTNCODFM ;signal no errors as default condition.
STORFMWK LDA (A4L),Y ;Copy FM work buf to FM work area.
STA FMWKAREA,Y
INY
CPY #45 ;45 bytes to copy (0 to 44).
BNE STORFMWK
CLC ;WHY?????
(AE7D) RTS
(AB0D) LDA OPCODEFM ;Check if opcode is legal.
CMP #13 ;(Must be less than 13.)
BCS TOERROP ;Opcode too large so got range error.
ASL ;Double val of opcode & put it in (x)
TAX ;so it indexes tables of adrs.
LDA FMFUNCTB+1,X ;Stick adr of appropriate function
PHA ;handler on stack (hi byte first).
LDA FMFUNCTB,X
PHA
(AB1E) RTS ;DO STACK JUMP TO FUNCTION ENTRY POINT.
.
.
(AB22) .
FNOPEN .
.
(See dis'mbly of OPEN function.)
.
.
- uses part of COMNOPEN routine.
- reads in VTOC to get link to 1rst directory.
- reads directory secs in & looks for file
description entry with matching filename.
- if matching name found, reads in the
1rst T/S list sector belonging to the file.
- if no match found, starts a new file by:
(1) creates new file description entry
- copies name to 1rst available spc
in direc sec (if can't find spc, then
issues disk full error message).
- allocates secs for file.
- writes updated VTOC to disk.
- puts link to first T/S list, file size, etc
in directory entry space.
- writes directory sector buffer to disk.
(2) creates new T/S list & writes it to disk.
- reads T/S list back into T/S list buf.
.
.
(RTS)
============
(AB1F)
TOERROP JMP RNGERROP ;Go handle range error.
------------ ;(See dis'mbly of errors.)
* Return here after doing the OPEN FUNCTION.
* (Cause after @ function is done, use stack
* to get back to the original caller.)
(A6AB)
AFTRFUNC BCC FMDRVRTN ;(c) = 0 = no errors.
LDA RTNCODFM ;Get error code from FM parameter list.
CMP #$5 ;End-of-data error?
(A6B2) BEQ TOAPPTCH ;Yes - encountered a zeroed-out T/S link or
;a zeroed-out data pair in T/S list.
;(Not applicable to the open function.)
(A6B4) JMP OTHRERR ;No - see dis'mbly of errors.
------------
(A6C3)
FMDRVRTN RTS
(A3DC) PLA ;Get file type wanted off of stack.
(A3DD) JMP CHKFTYPE ;Go check if type wanted equals type found.
------------
- Check if file type wanted = file type found.
- (If using open command to open a pre-exisiting file,
- may get a type mismatch. However, a mismatch error
- is not possible when opening a new file.)
(A7C4)
CHKFTYPE EOR FILTYPFM ;Type found (via open function).
(A7C7) BEQ CKTYPRTN ;Branch if type wanted = type found.
- File types didn't match.
- Check if correct type but locked.
(A7C9) AND #%01111111 ;Maybe matched-disregard lock bit.
(A7CB) BEQ CKTYPRTN ;Branch if matched.
- Type wanted < > type found!!!!!
- So go close file & then issue a
- type mismatch error message.
(A7CD) JSR CMDCLOSE ;Wrong kind of file so go close it.
* Because the file is already open, execution flows
* thru the close cmd twice. The first time thru, the matching
* DOS filename buffer is located & then CLOSEONE is used to
* close the file via the open FUNCTION. The 2nd time thru, a
* matching filename buffer is not found because the DOS
* buffer was released on the first pass. Therefore, A5L/H is
* left pointing at the highest numbered (lowest in memory)
* FREE DOS buffer when the close command is exited via EVENTXIT
* and CLOSERTS.
* (P.S. NOT ALL RAMIFICATIONS OF THE CLOSE COMMAND ARE SHOWN
* BELOW. (For more details, see the formatted disassembly
* dedicated solely to the close command.)
(A2EA)
CMDCLOSE LDA PRIMFNBF ;Get 1rst char from primary name buffer.
CMP #" " ;Don't allow leading <spc> in name.
(A2EF) BEQ CLOSEALL ;Leading <spc> = signal to close all files.
;(A close cmd was issued with no
;accompanying file name.)
(A2F1) JSR GETBUFF ;Locate a DOS file buffer.
* Locate buffer with same name.
* If that fails, locate a free buffer.
(A764)
GETBUFF LDA #0 ;Default hi-byte of pointer to 0
STA A5L+1 ;(ie. assume no free buff available).
(A768) JSR GETFNBF1 ;Get pointer to 1rst filename buffer in chain.
(A792)
GETFNBF1 LDA ADOSFNB1 ;First link to chain of DOS buffers
LDX ADOSFNB1+1 ;(ie. pt 2 1rst name buf in chain).
(A798) BNE SETNXPTR ;ALWAYS.
(A7A4)
SETNXPTR STX A3L+1 ;Put addr of 1rst filename buffer in ptr
STA A3L ;(ie. highest name buffer in chain).
TXA ;Get hi-byte of addr in back in (a).
GETNXRTN RTS
(A7A9)
(A76B) JMP FNCHAR1 ;Get 1rst char from DOS name buf.
------------
(A76E)
GETFNLNK JSR GETNXBUF
* Get addr of next filename buffer in chain
* from chain pointers buffer offset 37 & 36
* bytes from 1rst char of present filename
* buffer.
(A79A)
GETNXBUF LDY #37 ;Point the pointer at the chain buffer &
LDA (A3L),Y ;get addr of the next filename buffer.
BEQ GETNXRTN ;If hi-byte is 0, then lnk zeroed out.
TAX ;Save hi-byte in (x).
DEY ;Pick up low-byte.
LDA (A3L),Y
SETNXPTR STX A3L+1 ;Stick addr of filename buffer in ptr.
STA A3L
TXA ;Get hi-byte back in (a).
GETNXRTN RTS
(A7A9)
(A771) BEQ NOFNMTCH ;Link zeroed out, end of chain.
FNCHAR1 JSR GETFNBY1 ;Get the 1rst char of filename from buf in chain.
(A773)
* Get first byte in DOS file name buf.
(A7AA)
GETFNBY1 LDY #0 ;Buffer is free if 1rst byte = $00.
LDA (A3L),Y ;If buf occuppied, the 1rst byte = 1rst
(A7AE) RTS ;char of filename which owns buffer.
(A776) BNE NXFNBUF ;Take branch if buffer wasn't free.
LDA A3L ;Buffer was free, there4, point the A5L/H pointer
STA A5L ;at the free buffer.
LDA A3L+1
STA A5L+1
(A780) BNE GETFNLNK ;ALWAYS.
(A782)
NXFNBUF LDY #29 ;Buffer not free there4 compare name
CMPFNCHR LDA (A3L),Y ;of owner with name of file in primary
CMP PRIMFNBF,Y ;name buffer. (Start with last char first.)
(A789) BNE GETFNLNK ;Char doesn't match, there4 look for another
;buffer that might have same name.
(A78B) DEY ;That char matched, how bout rest of name?
BPL CMPFNCHR ;30 chars in name (ie. 0 to 29).
CLC ;Clr carry to signal names match.
(A78F) RTS
============
(A790)
NOFNMTCH SEC ;Link zeroed out.
(A791) RTS
============
(A2F4)
EVENTXIT BCS CLOSERTS ;EVENTUALLY exit via this route.
(A2F6) JSR CLOSEONE ;Matching file name was found, so close that file.
* Close a specific file.
(A2FC)
CLOSEONE JSR CKEXCBUF
* Check if current filename buffer
* belongs to an EXEC file. After all,
* don't want to close buffer if we are
* using it to exec (ie. would be like
* burying ourselves alive).
(A7AF)
CKEXCBUF LDA EXECFLAG ;Check to see if EXECing.
BEQ NOTEXCBF ;No sweat - not running exec file.
LDA EXECBUFF ;We are EXECing, there4 chk if addr of
CMP A3L ;current filename buffer same as that
BNE CKEXCRTN ;for buffer belonging to EXEC.
LDA EXECBUFF+1 ;Maybe - low-bytes matched,
CMP A3L+1 ;so now check hi bytes of addr.
BEQ CKEXCRTN ;Exec buffer = current buffer.
NOTEXCBF DEX ;Not EXECing, DEX to make sure z-flag off.
(A7C2) ;(P.S. (x) was orig set to large non-zero
;val on entry to GETFNBF1. There4, if now
(A7C3) ;DEX, can be sure z-flag will be off.)
CKEXCRTN RTS ;Exit with: z-flag = 1 if execing.
; = 0 if not execing.
(A2FF) BNE FREEBUFF ;Not EXECing from this particular file.
LDA #0 ;Closing an exec file so shut
STA EXECFLAG ;off the exec flag.
FREEBUFF LDY #0 ;Free up the DOS buffer by poking a $00 in
TYA ;1rst byte of filename.
STA (A3L),Y
(A30B) JSR BUFS2PRM
* GET addresses of the DOS buffers from chain
* buffer & put them in FM parameter list.
(A74E)
BUFS2PRM LDY #30 ;Get addresses of FM Work buffer,
ADRINPRM LDA (A3L),Y ;T/S list buffer, Data sec buffer and
STA WRKBUFFM-30,Y ;NEXT filename buf from the chain ptr
INY ;buf & put them in the FM parameter list.
CPY #38 ;(P.S. addr of NEXT filename buffer not
BNE ADRINPRM ;used by DOS.)
(A75A) RTS
(A30E) LDA #2 ;Stick opcode for CLOSE function
STA OPCODEFM ;in the FM parameter list.
(A313) JMP FMDRIVER ;Get ready to do the function.
------------
(A6A8)
FMDRIVER JSR FILEMGR ;Call the file manager to do the function.
(AB06)
FILEMGR TSX ;Save stk ptr so we can rtn to caller
STX STKSAV ;(ie., set it to rtn to AFTRFUNC, $A6AB.)
(AB0A) JSR RSTRFMWA ;Copy contents of FM work buffer (in DOS
;chain) to FM work area (not in chain).
(AE6A)
RSTRFMWA JSR SELWKBUF ;Find FM work buffer.
* Get address of FM
* work buf from FM
* parm list & stick
* it in the A4L/H
* pointer.
(AF08)
SELWKBUF LDA #0
(AF0A) BEQ PT2FMBUF
(AF12)
PT2FMBUF LDA WRKBUFFM,X
STA A4L
LDA WRKBUFFM+1,X
STA A4L+1
(AF1C) RTS
(AE6D) LDY #0 ;Zero-out rtn code in
STY RTNCODFM ;lst 2 signal no errs.
STORFMWK LDA (A4L),Y ;Copy FM work buf
STA FMWKAREA,Y ;(in chain) to FM
INY ;wrk area (not in
CPY #45 ;DOS buf chain).
BNE STORFMWK
CLC ;Why?????
(AE7D) RTS
(AB0D) LDA OPCODEFM ;Chk if opcode is legal.
CMP #13 ;(Must be less than 13.)
BCS TOERROP ;Opcode too large, got range error.
ASL ;Double val of opcode & get addr of
TAX ;appropriate function handler from tbl.
LDA FMFUNCTB+1,X ;Put the adr on stack (hi byte first)
PHA ;& then do a "stack jump" to the appropriate
LDA FMFUNCTB,X ;function handler.
PHA
(AB1E) RTS
.
.
(AC06) .
FNCLOSE .
.
(See dis'mbly of CLOSE function.)
.
.
- if necessary, free up any sectors that
were previously allocated to the file
but not needed.
- also updates the file size, fixes up
links & updates data, VTOC, T/S list
& directory sectors if necessary.
.
.
(RTS)
============
(AB1F)
TOERROP JMP RNGERROP ;Go handle range error.
------------ ;(See dis'mbly of errors.)
* Return here after doing the CLOSE FUNCTION.
* (Cause after @ function is done, use stack
* to get back to the original caller.)
(A6AB)
AFTRFUNC BCC FMDRVRTN ;(c) = 0 = no errors.
LDA RTNCODFM ;Get error code from FM parameter list.
CMP #$5 ;End-of-data error?
(A6B2) BEQ TOAPPTCH ;Yes - encountered a zeroed-out T/S link or
;a zeroed-out data pair in T/S list.
;(Not applicable to the close function.)
(A6B4) JMP OTHRERR ;No - see dis'mbly of errors.
------------
(A6C3)
FMDRVRTN RTS
(A2F9) JMP CMDCLOSE ;Go back into CMDCLOSE to point A5L/H pointer
------------ ;at the highest numbered (lowest in
;memory) free filename buffer in chain of DOS
;buffers & then exit CMDCLOSE via EVENTXIT & CLOSERTS.
(A330)
CLOSERTS RTS
============
(A7D0) JMP TYPMISM ;See dis'mbly of errors.
------------ ;(Eventually goes into DOS's warm start routine.)
(A7D3)
CKTYPRTN RTS ;Exit to caller of the open command.
============ ;Usually returns to AFTRCMD ($A17D) located
;in the command parsing and processing routines.