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-=-=-=-=-=-=-
- *****************************************************************
- *
- WRITE Command Handler *
- *
- ----------------------------------------------------------------*
- *
- The WRITE command prepares the computer to send subsequent*
- output to the disk. The command can only be used in the *
- deferred mode. R(ecord number) and B(yte offset into record) *
- parameters are optional. The presence or absence of an R- *
- parameter determines if the file is treated as a random access *
- or sequential text file (respectively). If no byte parameter *
- is given, writing begins at the first byte in a specific *
- record of a random access file. *
- *
- Execution pattern: *
- The CMDWRITE routine ($A510) first calls the common read/ *
- write routine (COMRDWR, $A526) to locate a DOS buffer whose *
- name field contains the same name as the file wanted. If the *
- named file can't be located, CMDOPEN ($A2A3) is used to open *
- the file. If the file does not already exist on the disk, a *
- new file is created. Once a pre-existing or new file is *
- opened, a check is made to insure that the type code of the *
- wanted file matches that of the file just opened. If the *
- codes don't match, the file is closed and the command is *
- exited via a file-type-mismatch error. *
- Therefore, contrary to the information contained in THE *
- DOS MANUAL, it is NOT necessary to OPEN a file before writing *
- to it. If the file is not already open, the WRITE command *
- opens it for you. However, the WRITE command does not accept *
- an L-parameter. Therefore, if you wish to use a record length *
- greater than the default value of one, you must either use the *
- OPEN command or, using assembly language, bypass the command *
- interpreter and set the input buffer and parsed table *
- accordingly. *
- The COMRDWR routine eventually checks bits one and two of *
- CUMLOPTN ($AA65) to see if R- or B-parameters were issued with *
- the command. If either parameter was given, the file manager *
- (FILEMGR, $AB06) is called to do the position function *
- (FNPOSN, $AD12). FNPOSN uses the L-, R- and B-parameters to *
- calculate the desired position of the three-byte file pointer *
- (FILPTSEC, $B5E4-$B5E5 and FILPTBYT, $B5E6) via the following *
- forumula: *
- pointer position wanted = (record number * record length) *
- + byte offset into record. *
- Once the file pointer is adjusted, or if no positioning is *
- required, execution branches back into the CMDWRITE routine at *
- $A513. The output conditon flag (OPUTCOND, $AA52) is then set *
- to condition 5 and the write command is exited after the I/O *
- hooks are reset to point to DOS. *
- Although the WRITE command per se does not actually write *
- anything to file, it leaves the computer in the write mode so *
- that data contained in subsequent PRINT statements are output *
- to the file. (However, a PRINT statement containing DOS's *
- control character (usually a ctrl-D) cancels the write mode.) *
- When a subsequent PRINT statement is encountered, *
- execution eventually flows into the WRITEXT ($A60E) routine *
- which sets up the FM parameter list to do the write function. *
- After storing a single data byte in the ONEIOBUF buffer *
- ($B5C3), the FM parameter list is set to write one byte. The *
- file manager (FILEMGR, $AB06) is then called to do the write *
- function and write-one-byte subfunction. *
- The write function handler (FNWRITE, $AC70) merely checks *
- the operation subcode (SUBCODFM, $B5BC) and then does a stack *
- jump to the write-one-byte subfunction handler (WRITEONE, *
- $ACBE). WRITEONE sets the accummulator with the byte to be *
- written and then calls INCIOBUF ($B1A2) to point the A4L/H *
- pointer ($42, $43) at the source location. If the file *
- pointer points beyond the present data sector in memory, or if *
- no data sector is currently in memory, the NXTDATRD routine *
- ($B0B6) is used to read in the correct data sector. The *
- output data byte is then stored in the data sector buffer and *
- the file pointer is incremented. After conditionally *
- displaying the output byte, the I/O hooks are reset to point *
- to DOS and the stack is reset to return to the caller. *
- *
- Note that the write subfunctions do not necessarily write *
- data to the disk. At the very least, they store data in the *
- data sector buffer. If single data bytes are added repeatedly,*
- the data buffer eventually is filled up. Once this happens, *
- RWTS ($BD00) is finally called to actually write the data to *
- the disk. However, if the write mode is exited before the *
- data sector buffer is full, bit six of the update flag *
- (UPDATFLG, $B5D5) is set. When the file is eventually closed, *
- the close command detects the set bit and writes the data *
- sector buffer to the disk. (The close command also updates *
- the T/S list and directory sector buffers if necessary.) *
- *
- *****************************************************************
- Conditions on entry:
- - If MON C was previously used, the Applesoft program line
- containing the WRITE command has been printed on the screen.
- - A valid filename has been parsed and copied into the primary
- file name buffer (PRIMFNBF, $AA75).
- - If applicable, volume, drive, slot, record number and byte
- offset values have been parsed, checked for validity and
- stored in the parsed options table (VOLPRSD, DRVPRSD,
- SLOTPRSD, RECPRSD & BYTPRSD respectively).
- - Previous use of the OPEN command has also placed the record
- length (RECPRSD) in the parsed options table.
- - The appropriate DOS condition handler has copied an
- abbreviated version of the original Applesoft write command
- line into the input buffer (BUF200, $200). Delimiters have
- been dropped and the Applesoft end-of-line marker (eol, $00)
- has been replaced with a return code ($8D). For example, if
- the original Applesoft line was: 100 PRINT D$;"WRITE NAME",
- then the line was originally coded in memory (in positive
- ASCII form) as follows:
- 22 08 64 00 BA 44 24 3B 22 57 52 49 54 45 20 4E 41 4D 45 22 00
- . . . . . D $ ; " W R I T E spc N A M E " eol marker
- . . . . .
- . . . . ---> PRINT token
- . . . ----> line number (hi)
- . . -----> line number (low)
- . ------> ptr to next line (hi) (varies)
- -------> ptr to next line (low) (varies)
- The abbreviated (negative ASCII) version placed in the
- keyboard input buffer by DOS would be as follows:
- 84 D7 D2 C9 D4 E5 A0 CE C1 CD C5 8D
- . W R I T E spc N A M E rtn
- .
- ----> $84 = actual hex code for ctrl-D
-
- - The WRITE command is normally entered with OPUTCOND: 00,
- CONDNFLG: 00, and the I/O hooks pointing to the true I/O
- handlers (ex. CSW: COUT1 & KSW: KEYIN).
(A510)
CMDWRITE JSR COMRDWR ;Call common read/write routine.
* Code common to read/write.
(A526)
COMRDWR JSR GETBUFF ;Locate a DOS 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 ;Go get first byte of DOS name buffer.
------------
(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 link 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 from the DOS name buffer.
(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 match.
(A78F) RTS
============
(A790)
NOFNMTCH SEC ;Link zeroed out.
(A791) RTS
============
(A529) BCC BUFS4RW ;Branch if matching buffer was found
;(ie. file was already open).
* File not already open, so go open it.
(A52B) JSR CMDOPEN
(A2A3)
CMDOPEN LDA #0 ;0 = code for text file.
(A2A5) JMP OPNCKTYP ;Go open the file & chk its type.
------------
* Open a specific file & check 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
LDA LENPRSD+1
STA RECLENFM+1
CLSLOCBF JSR CMDCLOSE ;Close file if it's already open.
(A2C8)
(A2EA)
CMDCLOSE .
.
(See dis'mbly of CMDCLOSE.)
.
.
- because a matching filename does not
exist, only one pass is made through
the CLOSE command. A5L/H is normally
left pointing at the highest numbered
(lowest in memory) free DOS buffer when
CMDCLOSE is exited via EVENTXIT and
CLOSERTS. If no free buffer is
available, A5L/H contains a zero.
.
.
(RTS)
(A2CB) LDA A5L+1 ;Hi byte of A5L/H ptr 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
LDA A5L ;we will use for file name field buffer.
STA A3L
(A2D8) JSR CPYPFN
* Assign DOS buffer to file we want to
* open. Copy the name of the file wanted
* from the primary file name buf to the
* DOS buffer's filename field.
(A743)
CPYPFN LDY #29 ;30 bytes to copy
(A745) ;(0 to 29).
CPYPRIM LDA PRIMFNBF,Y ;Copy name of
STA (A3L),Y ;file wanted from
DEY ;primary name buf
BPL CPYRIM ;into the DOS
(A74D) RTS ;name buffer.
(A2DB) JSR BUFS2PRM
* Get addrs of the various DOS bufs
* from the chain buf & put them in
* the FM parameter list.
(A74E)
BUFS2PRM LDY #30 ;Get adr of FM work
ADRINPRM LDA (A3L),Y ;buf, T/S list buf,
STA WRKBUFFM-30,Y ;data sec buf
INY ;& next DOS name buf
CPY #38 ;from chain pointer
BNE ADRINPRM ;buf & put them in
(A75A) RTS ;FM parm list.
;(P.S. Adr of next
;DOS name buf is
;not used by DOS.)
(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 adr of the
STA FNAMBUFM ;primary name buf
LDA ADRPFNBF+1 ;from constants
(A735) STA FNAMBUFM+1 ;tbl and put it
;in FM parm list.
(A738) LDA A3L ;Save the adr of
STA CURFNADR ;current DOS name
LDA A3L+1 ;buf in table of
STA CURFNADR+1 ;DOS variables.
(A742) RTS
(A2E1) LDA TEMPBYT ;Get open opcode back from temporary buf
STA OPCODEFM ;and put it in the FM parameter list.
(A2E7) JMP FMDRIVER
------------
* USE THE FILE MANAGER DRIVER
* TO DO THE OPEN FUNCTION.
(A6A8)
FMDRIVER JSR FILEMGR ;Call the file manager to do function.
* File manager proper.
(AB06)
FILEMGR TSX ;Save stk pointer
(AB07) STX STKSAV ;so can later rtn
;to caller of FM.
(AB0A) JSR RSTRFMWA
* Copy FM work buf
* (in DOS chain) to
* FM work area (not
* in DOS chain).
(AE6A)
RSTRFMWA JSR SELWKBUF
l
l
----------------------
l * Get adr of FM work
l * buff from FM parm
l * list & put it in
l * A4L/H pointer.
l (AF08)
l SELWKBUF LDX #0
l (AF0A) BEQ PT2FMBUF
l
l (AF12)
l PT2FMBUF LDA WRKBUFFM,X
l STA A4L
l LDA WRKBUFFM+1,X
l STA A4L+1
l (AF1C) RTS
l ---------------------
l
l
* Zero out return
* code in FM parm
* 2 signal no errs.
(AE6D) LDY #0
(AE6F) STY RTNCODFM
* Copy FM work buf
* to FM work area.
(AE72)
STORFMWK LDA (A4L),Y
STA FMWKAREA,Y
INY
CPY #45
BNE STORFMWK
CLC
(AE7D) RTS
* Check if opcode is legal.
* (Must be less than 13.)
(AB0D) LDA OPCODEFM
CMP #13
(AB12) BCS TOERROP ;Opcode too large
;(got range err).
(AB14) ASL ;Double val of
(AB15) TAX ;opcode & put it
;in (x) so it
;indexes tbl of
;addresses.
(AB16) LDA FMFUNCTB+1,X ;Stick adr of
PHA ;the appropriate
LDA FMFUNCTB,X ;function hndlr
(AB1D) PHA ;on stack (hi byte
;first).
(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:
(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 msg).
- allocates secs for file.
- writes updated VTOC to disk.
- puts link to first T/S list, file
size, etc in directory entry spc.
- 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
buffer.
.
.
(RTS)
============
TOERROP JMP RNGERROP ;Range error. See
(AB1F) ------------ ;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 - got 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. Only take if got an error
------------ ;other than an end-of-data error.
;(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 - Check again
;but this time 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 through
* 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.
(A2EA)
CMDCLOSE .
.
(See dis'mbly of CLOSE command.)
.
.
(RTS)
(A7D0) JMP TYPMISM ;Go handle type mismatch error.
------------ ;(See dis'mbly of errors.)
CKTYPRTN RTS
(A7D3) ============
(A52E) JMP CKRBOPTN ;Go chk if R- or B-options were issued with the cmd.
------------
(A531)
BUFS4RW JSR BUFS2PRM
* Copy addresses of the different DOS buffers
* from the DOS chain buffer to 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
* Check if R- or B-parameters were issued with command.
(A534)
CKRBOPTN LDA CUMLOPTN ;Chk if R- or B- parms issued.
AND #%00000110 ;(R=$04, B=$02.)
(A539) BEQ RDWRRTN ;No - skip positioning of file pointer.
* Copy B- and R-parameters from option
* parsed table to FM parameter list.
(A53B) LDX #3
CPYBPARM LDA RECPRSD,X ;Get value of parameter.
STA RECNMBFM ;Store it in FM parameter list.
DEX ;4 bytes to copy (3 to 0).
(A544) BPL CPYBPARM ;More bytes to copy.
* CALL THE FILE MANAGER WITH THE POSITION OPCODE.
(A546)
BK2APND LDA #$0A ;Opcode for position.
STA OPCODEFM ;Put opcode in FM parm list.
(A54B) JSR FMDRIVER ;Call FM driver to do the position 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 return
STX STKSAV ;to the caller of the file manager.
(AB0A) JSR RSTRFMWA
* Copy FM work buf (in DOS chain) 2
* FM work area (not in DOS chain).
(AE6A)
RSTRFMWA JSR SELWKBUF
* Get addr of FM work
* buf from FM parm
* list & put it in
* the A4L/H pointer.
(AF08)
SELWKBUF LDX #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 return
(AE6F) STY RTNCODFM ;code in FM parm
;to assume no errs
;as default cond.
(AE72)
STORFMWK LDA (A4L),Y ;Copy FM work buf
STA FMWKAREA,Y ;to FM work area.
INY
CPY #45 ;45 bytes to copy.
BNE STORFMWK ;(0 to 44).
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.
.
.
(AD12) .
FNPOSN .
.
(See dis'mbly of POSITION function.)
.
.
(RTS)
============
TOERROP JMP RNGERROP ;Go handle range error.
(AB1F) ------------ ;(See dis'mbly of errors.)
* Return here after doing the POSITION 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 - got a zeroed-out T/S link or a
;zeroed-out data pair in T/S list.
;(Not applicable to the position function.)
(A6B4) JMP OTHRERR ;No. Only take if got an error
------------ ;other than an end-of-data error.
;(See dis'mbly of errors.)
(A6C3)
FMDRVRTN RTS
RDWRRTN RTS
(A54E) ============
(A513) LDA #5 ;Set condition 5.
STA OPUTCOND
(A518) JMP FINSHCMD ;Exit with condition 5 set so that the
------------ ;next time a "PRINT" statement is encountered,
;execution will flow via the DOS hooks to send
;chars to the named file.
- Finish off the DOS command.
(9F83)
FINSHCMD LDA BUF200 ;Get first char in buffer.
(9F86) CMP DCTRLCHR ;Was command done via DOS's control char?
;(Normally ctrl-D.)
(9F89) BEQ DSPLYCMD ;YES - ALWAYS TAKE WHEN ASSOC WITH WRITE CMD
; (cause abbreviated NEG ASCII version of Applesoft
; program line containing the WRITE cmd is still
; in the keyboard input buffer, BUF200).
(9F95)
DSPLYCMD LDA #%01000000 ;Set bit 6 to see if using "MON C".
(9F97) BNE DSPLYCHR ;ALWAYS.
(9F9F)
DSPLYCHR AND CIOCUMUL ;Test flag - see if should display.
(9FA2) BEQ DOSEXIT ;No - so just exit DOS with condition 5 still
; set to data will be routed to disk.
- MON C flag was on, so display command-terminating
- carriage return. (P.S. Applesoft detected the
- end-of-line marker ($00) and changed it to a <cr>.
- DOS then put the carriage return ($8D) as the last
- character in the input buffer.)
(9FA4)
DSPLYALL JSR RESTOREG
(9FBA)
RESTOREG LDA ASAVED ;Restore (a), (y) & (x) registers.
LDY YSAVED
LDX XSAVED
SEC ;Why?????
(9FC4) RTS
(9FA7) JSR GODSPLY ;Output char via true output handler.
(9FC5)
GODSPLY JMP (CSW)
------------
(FDF0)
COUT1 .
.
(Print char thru true output handler.)
(See dis'mbly of monitor in APPLE II REFERENCE MANUAL.)
.
.
(RTS)
============
(9FAA) STA ASAVED ;Save (a), (y) and (x) registers.
STY YSAVED
(9FB0) STX XSAVED
(9FB3)
DOSEXIT JSR INITIOHK ;Reset I/O hooks to point to DOS.
* Initialize the I/O hooks so that DOS intercepts
* all input & output. For instance, if a routine
* encounters a "COUT JMP (CSW)", then execution will
* actually flow to DOS's output routine (OPUTINCP,
* $9EBD). Similarly, any routine that refers to
* "RDKEY JMP (KSW)" will actually jump to DOS's
* input routine (INPTINCP, $9E81).
*
* The true (ie. normal) hooks are saved, ex:
* KSW: KEYIN --> KSWTRUE: KEYIN.
* CSW: COUT1 --> CSWTRUE: COUT1.
* The intercepts are then set as follows:
* ADINPTCP: INPTINCP --> KSW: INPTINCP.
* ADOPUTCP: OPUTINCP --> CSW: OPUTINCP.
* Check if the input hook needs to be reset.
(A851)
INITIOHK LDA KSW+1
CMP ADINPTCP+1
(A856) BEQ CKOUTHK ;Input hook already points to DOS's
;input handler, so go check output hook.
* Reset the input hook to point to DOS.
(A858) STA KSWTRUE+1 ;KSW: KEYIN --> KSWTRUE: KEYIN.
LDA KSW
STA KSWTRUE
LDA ADINPTCP ;ADINPTCP: INPTINCP --> KSW: INPTINCP.
STA KSW
LDA ADINPTCP+1
(A868) STA KSW+1
* Check if the output hook needs to be reset.
(A86A)
CKOUTHK LDA CSW+1
CMP ADOPUTCP+1
(A86F) BEQ SETHKRTN ;Output hook already points to DOS's
;output handler, so go exit.
* Reset the output hook to point to DOS.
(A871) STA CSWTRUE+1 ;CSW: COUT1 --> CSWTRUE: COUT1.
LDA CSW
STA CSWTRUE
LDA ADOPUTCP ;ADOPUTCP: OPUTINCP --> CSW: OPUTINCP.
STA CSW
LDA ADOPUTCP+1
STA CSW+1
SETHKRTN RTS
(A883)
(9FB6) LDX STKSAVED ;Retrieve saved stack pointer.
TXS ;(P.S. Don't confuse "STKSAVED" with "STKSAV".
RESTOREG LDA ASAVED ;Restore (a), (y) & (x) registers.
LDY YSAVED
LDX XSAVED
SEC ;Why?????
(9FC4) RTS ;Exit to caller of WRITE command.
============ ;Normally returns to $D533 in Applesoft ROM
;(part of INLINPL2 routine ($D52E).)
=:=:=:=:=:=:=:=:=:=:=:=:=:=:=:=:=:=:=:=:=:=:=:=:=:=:=:=:=:=:=:=:=
NOTE: The WRITE command was exited without actually writing
anything to the file. However, because OPUTCOND ($AA52) was left
with a value of $05, the next time Applesoft encounters a
"PRINT" statement, execution flows via COUT ($FDED) and the DOS
hooks to send the characters contained in the "PRINT" statement to
the file as shown below:
(FDED)
COUT JMP (CSW)
------------
- DOS's output intercept routine.
(9EBD)
OPUTINCP JSR PREP4DOS
(9ED1)
PREP4DOS STA ASAVED ;Save (a), (y) & (x) registers.
STX XSAVED
STY YSAVED
TSX ;Adjust stack pointer and save it so that when later
INX ;restore it and hit an "RTS", we can return to the routine
INX ;that contained the "JSR PREP4DOS" instruction.
STX STKSAVED
UNCONDOS LDX #3 ;Handy entry point frequently used by assembly
(9EE0) ;language programmers to disconnect DOS completely.
(9EE2)
SETRUHKS LDA CSWTRUE,X ;Restore the I/O hooks to point to the true
STA CSW,X ;I/O handlers, ex: KSWTRUE: KEYIN --> KSW: KEYIN.
DEX ; CSWTRUE: COUT1 --> CSW: COUT1.
BPL SETRUHKS ;4 bytes (0 to 3) to move.
(9EEA) RTS
- Use current OPUTCOND value to index table containing
- address of output condition handlers. Do a "stack jump"
- to the appropriate condition handler entry point.
(9EC0) LDA OPUTCOND
ASL ;Times 2 cause 2 bytes/address.
TAX ;Set (x) to index table of entry point addresses.
LDA OPUTHNDTB+1,X ;Put adr of output handler on stack
PHA ;(hi byte first) and then do a "stack jump"
LDA OUTHNDTB,X ;to the appropriate entry point.
PHA
LDA ASAVED ;Save char to be printed.
(9ED0) RTS ;Execute the "stack jump".
.
.
STACK JUMP TO OPUTHDL5
.
.
- Output handler 5.
- - denotes start of writing chars to file.
- - evaluate start of data to write.
(9F61)
OPUTHDL5 CMP DCTRLCHR ;Is char = DOS's ctrl char (normally Ctrl-D)?
(9F64) BEQ OPUTHDL0 ;If (a) = DOS's ctrl char, exit via OPUTHDL0
;to cancel WRITE mode. This is why a
;statement such as: PRINT D$ will exit the
;write mode with the file still open. (Such
;a statement is often called a NULL command
;in the literature.)
(9F66) CMP #$8A ;line feed?
BEQ CMWRTBYT ;Yes - go write <lf> but stay in condition 5.
LDX #4 ;No - reset to condition 4 to signal that
STX OPUTCOND ; we want to write another line.
(9F6F) BNE OPUTHDL4 ;ALWAYS.
- Output handler 4.
- Writing data to the disk.
(9F52)
OPUTHDL4 CMP #$8D ;<cr>?
BNE CMWRTBYT ;No.
LDA #5 ;Set condition 5.
STA OPUTCOND
CMWRTBYT JSR WRITEXT ;Go write data byte to file.
(9F5B)
(A60E)
WRITEXT JSR CKBSCRUN
* Check if basic is running a program.
(A65E)
CKBSCRUN PHA ;Save (a) on stack.
LDA ACTBSFLG ;Check which basic is presently up.
(A662) BEQ INTBASIC ;Branch if using Integer basic.
* Using Applesoft - now if the line number
* is > 65288 ($FF in hi byte), then using
* immediate mode.
(A664) LDX CURLIN+1 ;Check hi byte of line number.
INX ;If $FF --> $00, then line # > 65288.
(A667) BEQ IMEDMODE ;Branch if using immediate mode.
* Applesoft appears to be running a prgm but, maybe
* CURLIN+1 was zapped, so also check prompt.
(A669) LDX PROMPT
CMP #$DD ;RH brackett = Applesoft prompt.
BEQ IMEDMODE ;Branch if in immediate mode.
RUNNING PLA ;Get saved (a) back from stack.
CLC ;(c) = 0 = signal program is running.
(A671) RTS
============
(A672)
INTBASIC LDA RUNMODE ;Check integer basic's run mode flag.
BMI RUNNING ;If negative, integer basic up but in deferred mode.
IMEDMODE PLA ;Get saved (a) back from stack.
SEC ;(c) = 1 = signal in immediate mode.
(A678) RTS
============
(A611) BCS CLOSZERO ;Basic prgm is not running, so go close
;the file, reset to condition 0 & then do
;a warmstart. (Remember, the WRITE
;command is restricted to the deferred mode.)
(A613) LDA ASAVED ;Retrieve byte to write.
STA ONEIOBUF ;Put it in the FM parameter list.
LDA #4 ;Set FM parm list to WRITE ONE BYTE.
STA OPCODEFM
LDA #1
STA SUBCODFM
(A623) JMP FMDRIVER ;Go to FM driver to write data byte.
------------
(A6A8)
FMDRIVER JSR FILEMGR ;CALL THE FILE MANAGER TO DO THE WRITE FUNCTION.
* File manager proper.
(AB06)
FILEMGR TSX ;Save stk pointer so can later rtn to caller of FM.
STX STKSAV
(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 ;assume 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.
.
.
(AC70) .
FNWRITE .
.
(See dis'mbly of FNWRITE function and
write-one-byte (WRITEONE, $ACBE) subfunction.)
.
.
(RTS)
============
TOERROP JMP RNGERROP ;Go handle range error.
(AB1F) ------------ ;(See dis'mbly of errors.)
* Return here after doing the WRITE 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 - got a zeroed-out T/S link or a
;zeroed-out data pair in T/S list.
;(Not applicable to the write function.)
(A6B4) JMP OTHRERR ;No. Only take if got an error
----------- ;other than an end-of-data error.
;(See dis'mbly of errors.)
(A6C3)
FMDRVRTN RTS
(9F5E) JMP DSPLYOUT ;Go display output conditionally.
------------
(9F99)
DSPLYOUT LDA #%00010000 ;Set bit pos'n 4.
(9F9B) BNE DSPLYCHR ;ALWAYS.
(9F9F)
DSPLYCHR AND CIOCUMUL ;Test flag to see if "MON O" is on.
(9FA2) BEQ DOSEXIT ;Flag to echo output is off, so skip screen print.
- Unconditionally dislay char.
(9FA4)
DSPLYALL JSR RESTOREG
* Restore the registers.
(9FBA)
RESTOREG LDA ASAVED ;Restore (a), (y) & (x) registers.
LDY YSAVED
LDX XSAVED
SEC ;Why?????
(9FC4) RTS
(9FA7) JSR GODSPLY ;Output char via true output handler.
(9FC5)
GODSPLY JMP (CSW)
------------
(FDF0)
COUT1 .
.
(Print char thru true output handler.)
(See dis'mbly of monitor in APPLE IIREFERENCE MANUAL.)
.
.
(RTS)
============
(9FAA) STA ASAVED ;Save (a), (y) and (x) registers.
STY YSAVED
(9FB0) STX XSAVED
(9FB3)
DOSEXIT JSR INITIOHK ;Reset I/O hooks to point to DOS.
* Initialize the I/O hooks so that DOS intercepts
* all input & output. For instance, if a routine
* encounters a "COUT JMP (CSW)", then execution will
* actually flow to DOS's output routine (OPUTINCP,
* $9EBD). Similarly, any routine that refers to
* "RDKEY JMP (KSW)" will actually jump to DOS's
* input routine (INPTINCP, $9E81).
*
* The true (ie. normal) hooks are saved, ex:
* KSW: KEYIN --> KSWTRUE: KEYIN.
* CSW: COUT1 --> CSWTRUE: COUT1.
* The intercepts are then set as follows:
* ADINPTCP: INPTINCP --> KSW: INPTINCP.
* ADOPUTCP: OPUTINCP --> CSW: OPUTINCP.
* Check if the input hook needs to be reset.
(A851)
INITIOHK LDA KSW+1
CMP ADINPTCP+1
(A856) BEQ CKOUTHK ;Input hook already points to DOS's
;input handler, so go check output hook.
* Reset the input hook to point to DOS.
(A858) STA KSWTRUE+1 ;KSW: KEYIN --> KSWTRUE: KEYIN.
LDA KSW
STA KSWTRUE
LDA ADINPTCP ;ADINPTCP: INPTINCP --> KSW: INPTINCP.
STA KSW
LDA ADINPTCP+1
(A868) STA KSW+1
* Check if the output hook needs to be reset.
(A86A)
CKOUTHK LDA CSW+1
CMP ADOPUTCP+1
(A86F) BEQ SETHKRTN ;Output hook already points to DOS's
;output handler, so go exit.
* Reset the output hook to point to DOS.
(A871) STA CSWTRUE+1 ;CSW: COUT1 --> CSWTRUE: COUT1.
LDA CSW
STA CSWTRUE
LDA ADOPUTCP ;ADOPUTCP: OPUTINCP --> CSW: OPUTINCP.
STA CSW
LDA ADOPUTCP+1
STA CSW+1
SETHKRTN RTS
(A883)
(9FB6) LDX STKSAVED ;Retrieve saved stack pointer.
TXS ;(P.S. Don't confuse "STKSAVED" with "STKSAV".)
RESTOREG LDA ASAVED ;Restore (a), (y) & (x) registers.
LDY YSAVED
LDX XSAVED
SEC ;Why?????
(9FC4) RTS ;Exit to caller.
============
- Tried to write file while in the immediate mode.
- Close the file, set condition 0 and exit DOS.
- (Note: We can clear bit1 of the byte at $A91F
- in the command attribute table (CMDATTRB) and
- NOP-out the "BCS CLOSZERO" instruction at $A611
- in order to enable the write command to operate
- from the immediate mode.)
(A679)
CLOSZERO JSR CLOSEONE ;Go close the file.
* Close the file specified.
(A67C)
CLOSEONE .
.
(See dis'mbly given in formatted
listing of the the close command.)
.
.
(RTS)
(A67C) JSR RESTAT0
* Reset CONDNFLG and OPUTCOND to 0.
(A75B)
RESTAT0 LDY #0
STY CONDNFLG
STY OPUTCOND
(A763) RTS
(A67F) JMP DOSEXIT ;(Go back to exit DOS.)
------------