💾 Archived View for spam.works › mirrors › textfiles › apple › ANATOMY › cmdexec.2.txt captured on 2023-06-16 at 21:11:04.
View Raw
More Information
-=-=-=-=-=-=-
- -:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:*
- *
- Note: Actual EXECing of statements does not occur until *
- after the computer returns to BASIC's RESTART routine ($D43C). *
- When input is requested, execution flows via the DOS hooks *
- into INPTINCP ($9E81). Here the exec flag is tested and *
- discovered to be set. As a result, the READEXEC routine *
- ($A682) is used to read data from the exec file. The state- *
- ments are interpreted as if they were encountered in the *
- immediate mode. *
- *
- Condition of major flags on entry: *
- - CONDNFLG ($AA51) = $00 = warmstart. *
- - ACTBSFLG ($AAB6) = $40 = Floating point basic in ROM. *
- - RUNTRUPT ($AAB7) = $00 = assume RUN cmd was not *
- interrupted. *
- - BASICCLD ($E000) = first byte of basic's coldstart *
- routine distinguishes type of *
- basic being used ($40 = A(ROM). *
- - OPUTCOND ($AA52) = $00 = evaluate start of input line.*
- - EXECFLAG ($AAB3) = non-zero value (actually the first *
- character of the exec filename). *
- = execing. *
- *
- NOTE THE FOLLOWING DISASSEMBLY IS INCOMPLETE. It is only *
- meant to provide a simplified example of the execution pattern *
- used by the EXEC command. *
- *
- -:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:*
- NOTE: YOU ARE LEAVING THE COMFORTABLE WORLD
- OF DOS AND ENTERING THE MURKY REALM OF BASIC.
- BASIC's warmstart routine.
- GO THROUGH A LOT OF STEPS TO PRINT
- A CARRIAGE RETURN.
(D43C)
RESTART JSR CRDO
(DAFB)
CRDO LDA #$0D ;Positive ASCII for <cr>.
(DAFD) JSR OUTDO
(DB5C)
OUTDO ORA #$80 ;Convert to neg ASCII.
CMP #" " ;Is it a ctrl char.
BCC GODOPUT ;Branch if ctrl char.
ORA FLSHMSK ;;$40 for FLASH, $00 for INVERSE or NORMAL.
GODOPUT JSR COUT ;Go to the output handling routine.
(DB64)
(FDED)
COUT JMP (CSW)
------------
* DOS's output intercept routine.
(9EBD)
OPUTINCP JSR PREP4DOS
* Prepare for processing by DOS.
(9ED1)
PREP4DOS STA ASAVED ;Save (a), (y) & (x)
STX XSAVED ;registers.
STY YSAVED
TSX ;Adjust stack ptr &
INX ;save it so when we
INX ;later restore it &
(9EDD) STX STKSAVED ;then hit an "RTS"
;we will return to
;the ROUTINE THAT
;CALLED THE ROUTINE
;THAT CONTAINED THE
;"JSR SETUP".
;(In this case,
;set saved stk ptr
;to rtn to $DB67.)
* Handy entry point frequently
* used by assembly language
* programmers to disconnect
* DOS completely.
(9EE0)
UNCONDOS LDX #3
SETRUHKS LDA CSWTRUE,X ;Restore the I/O
STA CSW,X ;hooks 2 pt 2 the
DEX ;true I/O handlers.
BPL SETRUHKS ;4 bytes to move
(9EEA) RTS ;(0 to 3).
* 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 tbl of entry pt addrs.
LDA OUTHNDTB+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 ;Get char to be printed.
(9ED0) RTS ;Execute the "stack jump".
.
.
STACK JUMP TO OPUTHDL0
.
.
* Output handler 0.
* (Evaluate start of line.)
(9EEB)
OPUTHDL0 LDX RUNTRUPT ;Was a RUN interrupted?
(9EEE) BEQ NONTRUPT ;Branch if not.
* File not being read.
(9EF3)
NONTRUPT LDX CONDNFLG ;Are we doing a warmstart ($00),
;coldstart ($80), using A(RAM) ($C0)
;or doing a READ ($01)?
(9EF6) BEQ SETIGNOR ;Branch if warmstarting.
* Doing a warmstart so set condition 2 as a
* default to signal that non-DOS commands
* should be ignored.
(9F00)
SETIGNOR LDX #2 ;SET CONDITION 2.
STX OPUTCOND
CMP DCTRLCHR ;Is the char = DOS's control character?
(9F08) BNE OPUTHDL2 ;No, it is a <cr> so branch.
* Output handler 2.
* (Ignore non-DOS commands.)
(9F23)
OPUTHDL2 CMP #$8D ;Is char a <rtn>?
BNE DSPLYALL ;Yes - fall thru.
SET2EVAL LDX #0 ;SET CONDITION 0 - evaluate start
STX OPUTCOND ;of line.
(9F2C) JMP DSPLYALL ;Go display char unconditionally.
------------
* Display the char.
(9FA4)
DSPLYALL JSR RESTOREG
* Restore (a), (y) & (x) registers.
(9FBA)
RESTOREG LDA ASAVED
LDY YSAVED
LDX XSAVED
SEC ;Why?????
(9FC4) RTS
(9FA7) JSR GODSPLY
* PRINT A <CR> THROUGH THE TRUE
* OUTPUT HANDLER.
(9FC5)
GODSPLY JMP (CSW)
------------
(FDF0)
COUT1 .
.
(See dis'mbly in APPLE II REFERENCE MANUAL.)
.
.
(RTS)
* Save registers.
(9FAA) STA ASAVED ;Save (a), (y) & (x) registers.
STY YSAVED
(9FB0) STX XSAVED
* Reset hooks & stack pointer.
(9FB3)
DOSEXIT JSR INITIOHK ;Reset DOS hooks.
* 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
* rout'n that refers 2 "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 input hk needs 2 be reset.
(A851)
INITIOHK LDA KSW+1
CMP ADINPTCP+1
(A856) BEQ CKOUTHK ;Input hk already
;pts 2 DOS's input
;handler, so go chk
;the oputput hook.
* Save true input hook and then reset
* the input hook to point to DOS.
* (KSW: KEYIN --> KSWTRUE: KEYIN)
* (ADINPTCP: INPTINCP --> KSW: INPTINCP)
(A858) STA KSWTRUE+1
LDA KSW
STA KSWTRUE
LDA ADINPTCP
STA KSW
LDA ADINPTCP+1
(A868) STA KSW+1
* Check if output hk needs 2 be reset.
(A86A)
CKOUTHK LDA CSW+1
CMP ADOPUTCP+1
(A86F) BEQ SETHKRTN ;Output hk already
;points to DOS's
;output handler,
;so go exit.
* Save true output hook and then reset
* the output hook to point to DOS.
* (CSW: COUT1 --> CSWTRUE: COUT1)
* (ADOPUTCP: OPUTINCP --> CSW: OPUTINCP)
(A871) STA CSWTRUE+1
LDA CSW
STA CSWTRUE
LDA ADOPUTCP
STA CSW
LDA ADOPUTCP+1
STA CSW+1
SETHKRTN RTS
(A883)
* Reset stack pointer & save registers.
(9FB6) LDX STKSAVED ;Retrieve the saved stack pointer value
TXS ;& reset the stack to return to caller.
RESTOREG LDA ASAVED ;Restore (a), (y) & (x) registers.
LDY YSAVED
LDX XSAVED
SEC ;Return to routine that called routine
(9FC4) RTS ;that contained "JSR PREP4DOS" instruc.
* Convert char back to positive ASCII
* so we can keep Applesoft happy.
(DB67) AND #$7F ;Convert char.
PHA ;Save it on the stack.
LDA SPEEDFLG ;Delay in accordance with speed setting.
(DB6C) JSR WAIT
* Monitor ROM's main delay routine.
* Delay z number of cycles based on
* the formula:
* z = ((5 * a^2) + (27 * a) + 26) / 2
* where a = value in accumulator on entry.
(FCA8)
WAIT SEC ;Prepare for subtraction.
WAIT2 PHA ;Save (a) on the stack.
WAIT3 SBC #1 ;Keep on reducing (a)
BNE WAIT3 ;until it equals zero.
PLA ;Get original val of (a) off stack.
SBC #1 ;Reduce original (a) down to 0 again.
BNE WAIT2
(FCB3) RTS
(DB6F) PLA ;Get saved positive ASCII char back from stack.
(DB70) RTS
(DB00) EOR #$FF ;No reason for this???
(DB02) RTS
- PRINT THE APPLESOFT PROMPT through
- Basic, DOS's output handler (OPUTINCP)
- and the monitor. THEN, INTERCEPT INPUT
- through DOS's input handler (INPTINCP).
(D43F) LDX #$DD ;RH brackett for Applesoft prompt.
(D441) JSR INLINPL2
(D52E)
INLINPL2 STX PROMPT
(D530) JSR GETLN
* Get a line of input.
(FD6A)
GETLN LDA PROMPT ;Print prompt.
(FD6C) JSR COUT
(FDED)
COUT JMP (CSW) ;Output hook pts to DOS's output handler.
------------
* DOS's output intercept routine.
(9EBD)
OPUTINCP JSR PREP4DOS
(9ED1)
PREP4DOS STA ASAVED ;Save (a), (y) & (x)
STX XSAVED ;registers.
STY YSAVED
TSX ;Adjust stk ptr and
INX ;save it so that
INX ;when we later
(9EDD) STX STKSAVED ;restore it and hit
;an "RTS", we can
;return to routine
;that called the
;routine that
;contained the
;"JSR PREP4DOS"
;instruction.
;(In this case,
;set saved stk ptr
;to rtn to $FD6F.)
* Restore the I/O hooks to point to the
* true I/O handlers, ex:
* KSWTRUE: KEYIN --> KSW: KEYIN.
* CSWTRUE: COUT1 --> CSW: COUT1.
(9EE0)
UNCONDOS LDX #3
SETRUHKS LDA CSWTRUE,X
STA CSW,X
DEX
BPL SETRUHKS ; 4 bytes to move
(9EEA) RTS ;(0 to 3).
* 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 addresses.
LDA OUTHNDTB+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 ;Get char to be printed.
(9ED0) RTS ;Execute the "stack jump".
.
.
STACK JUMP TO OPUTHDL0
.
.
* Output handler 0.
* (Evaluate start of line.)
(9EEB)
OPUTHDL0 LDX RUNTRUPT ;Was a RUN interrupted?
(9EEE) BEQ NONTRUPT ;Branch if not.
(9EF3)
NONTRUPT LDX CONDNFLG ;Are we doing a warmstart ($00),
;coldstart ($80), using A(RAM) ($C0)
;or doing a read ($01)?
(9EF6) BEQ SETIGNOR ;Branch if warmstarting.
* Warmstarting, so set condition 2.
(9F00)
SETIGNOR LDX #2 ;SET CONDITION 2 as a default to signal
STX OPUTCOND ;that we should ignore non-DOS commands.
CMP DCTRLCHR ;Is char = DOS's ctrl char?
(9F08) BNE OPUTHDL2 ;No, it is a prompt so take branch.
* Output handler 2.
* (Ignore non-DOS commands.)
(9F23)
OPUTHDL2 CMP #$8D ;<rtn>?
(9F25) BNE DSPLYALL ;No, isn't a <cr> so take branch.
* Display the char.
(9FA4)
DSPLYALL JSR RESTOREG
* Restore (a), (y) & (x) registers.
(9FBA)
RESTOREG LDA ASAVED
LDY YSAVED
LDX XSAVED
SEC ;Why?????
(9FC4) RTS
(9FA7) JSR GODSPLY
(9FC5)
GODSPLY JMP (CSW)
------------
* PRINT APPLESOFT PROMPT through
* the true output handler.
(FDF0)
COUT1 .
.
- print char thru true output handler.
(See dis'mbly in APPLE II REFERENCE MANUAL.)
.
.
(RTS)
* Save registers & reset hooks.
(9FAA) STA ASAVED ;Save (a), (y) & (x) registers.
STY YSAVED
(9FB0) STX XSAVED
* Routine to exit DOS.
(9FB3)
DOSEXIT JSR INITIOHK
* Initialize the I/O hooks so that DOS
* intercepts all input & output.
(A851)
INITIOHK .
.
(See dis'mbly above.)
.
.
(RTS)
(9FB6) LDX STKSAVED ;Retrieve the saved stack pointer val
TXS ;& reset the stack to return to caller.
RESTOREG LDA ASAVED ;Restore (a), (y) & (x) registers.
LDY YSAVED
LDX XSAVED
SEC ;Return to the routine that called the
(9FC4) RTS ;routine that contained the "JSR PREP4DOS"
;instruction.
*******************************
* *
* GET A SINGLE BYTE OF INPUT.
* *
*******************************
(FD6F) LDX #1
BCKSPC TXA ;Force fall thru to next instruction.
BEQ GETLNZ
DEX ;Initialize (x) = 0 as index to input buf.
NXTCHAR JSR RDCHAR
(FD75)
* Routine to read an input byte.
(FD35)
RDCHAR JSR RDKEY
(FD0C)
RDKEY LDY CH ;Get horiz cursor
;pos'n 4 nxt char.
(FD0E) LDA (BASL),Y ;Pick up char in next
(FD10) PHA ;screen pos'n & save
;it on the stack.
(FD11) AND #$3F ;Convert char to
ORA #$40 ;flashing.
(FD15) STA (BASL),Y ;Put flashing char
;on scrn to serve
;as cursor.
(FD17) PLA ;Get char back that
;cursor is replacing.
;(Need it in case do
;bkspc or -> and
;want to reinstate
;orig char on scrn).
(FD18) JMP (KSW) ;Input hook still
------------ ;pointing to DOS.
* DOS intercepts input.
(9E81)
INPTINCP JSR PREP4DOS ;Save regs & stk ptr
* Pt hks at true
* I/O handlers.
* (Adjust & save
* stk ptr to
* later return
* to $FD38.)
(9ED1)
PREP4DOS .
.
(See dis'mbly
above.)
.
.
(RTS)
(9E84) LDA CONDNFLG ;Test condition.
(9E86) BEQ INPUTWRM ;Branch if warmstart.
* Using warmstart condition.
* At this point, both CONDNFLG
* & OPUTCOND = 0 for both
* cold- and warmstarts.
(9E9E)
INPUTWRM LDA EXECFLG ;Are we execing?
BEQ INPTNOXC ;No
(9EA3) JSR READEXEC ;Yes - go read an
;exec file byte.
* Exec's read routine
(A682)
READEXEC .
.
.
.
-------------------------------------------------------------------------------------------------------------------
l * EXEC's read data routine.
l (A682)
l READEXEC JSR PT2EXEC
l
l * Point the A3L/+1 pointer at the
l * buffer we're execing in.
l (A69D)
l PT2EXEC LDA EXECBUFF+1 ;Get addr of DOS buf using to exec.
l STA A3L+1 ;Put in in the A3L/+1 pointer.
l LDA EXECBUFF
l STA A3L
l (A6A7) RTS
l
l (A685) JSR BUFS2PRM
l
l * Copy addresses of the various DOS
l * buffers from the chain buffer to
l * the FM parameter list.
l (A74E)
l BUFS2PRM LDY #30 ;Get addr of FM work buf, T/S list
l ADRINPRM LDA (A3L),Y ;buf, data sector buf & next DOS
l STA WRKBUFFM-30,Y ;file name buf from the chain
l INY ;pointers buf & put then in the FM
l CPY #38 ;parameter list. (P.S. Address of
l BNE ADRINPRM ;next DOS filename buf is not used
l (A75A) RTS ;by DOS.)
l
l (A688) LDA #3 ;SET CONDITION 3 so process
l (A68A) BNE SETCOND ;data input from the disk.
l -----------
l
l (A62D)
l SETCOND STA OPUTCOND
l (A630) JSR RDTXTBYT ;Go read a text file byte
l
l (A68C)
l RDTXTBYT LDA #3 ;Set READ opcode.
l STA OPCODEFM
l LDA #1 ;Set one-byte subcode.
l STA SUBCODFM
l (A696) JSR FMDRIVER ;Call the FM driver to read a data byte.
l
l * Use the file manager driver
l * to do the READ function.
l (A6A8)
l FMDRIVER JSR FILEMGR ;Call the file manager to do the function.
l
l * File manager proper.
l (AB06)
l FILEMGR TSX ;Save stk ptr so can later rtn 2 caller.
l STX STKSAV
l (AB0A) JSR RSTRFMWA
l
l * Copy FM work buf (in DOS chain) to
l * FM work area (not in DOS chain).
l (AE6A)
l RSTRFMWA JSR SELWKBUF
l
l * Get adr of FM work
l * buf from FM parm
l * list & put it in
l * the A4L/+1 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 * Do the copying.
l (AE6D) LDY #0 ;Zero out return code
l (AE6F) STY RTNCODFM ;in FM parm list to
l ;signal no errors as
l (AE72) ;default condition.
l STORFMWK LDA (A4L),Y ;Copy FM work buf
l STA FMWKAREA,Y ;to FM work area.
l INY
l CPY #45 ;45 bytes to copy
l BNE STORFMWK ;(0 to 44).
l CLC ;Why?????
l (AE7D) RTS
l
l (AB0D) LDA OPCODEFM ;Check if opcode is legal.
l CMP #13 ;(Must be less than 13.)
l BCS TOERROP ;Opcode too large so got range error.
l ASL ;Double val of opcode & put it in (x)
l TAX ;so it indexes tables of adrs.
l LDA FMFUNCTB+1,X ;Stick adr of appropriate function
l PHA ;handler on stack (hi byte first).
l LDA FMFUNCTB,X
l PHA
l (AB1E) RTS ;DO "STACK JUMP" TO FUNCTION ENTRY POINT.
l
l (AC58)
l FNREAD LDA SUBCODFM ;Check if subcode is legal.
l CMP #5 ;(Must be < = 5.)
l (AC5D) BCS TOERRSUB ;Error - illegal subcode.
l ;(Not applciable to exec command.)
l (AC5F) ASL ;Subcode * 2, cause 2 bytes/address.
l LDA RDSUBTBL+1,X ;Get address (minus 1) of subfunction
l PHA ;entry point & stick it on the stack
l LDA RDSUBTBL,X ;(hi byte first). Then do a "stack
l PHA ;jump" to execute the given READ sub-
l (AC69) RTS ;function. (Exec command ALWAYS uses
l ;the READ-ONE-BYTE subfunction.)
l
l (AC8A)
l READONE .
l .
l (See dis'mbly of the
l read-one-byte subfunction.)
l .
l .
l (RTS)
l ============
l
l TOERROP JMP RNGERROP ;Go handle range error.
l (AB1F) ------------ ;(See dis'mbly of errors.)
l
l TOERRSUB JMP RNGERRSB ;Go handle range error.
l (AC6A) ------------ ;(See dis'mbly of errors.)
l
l * Return here after doing the READ function.
l * (Cause after @ function is done, use stack
l * to get back to the original caller.) Note that
l * (c) = 0 if a data byte was just read (regardless
l * of whether that data byte was a $00 or not).
l (A6AB)
l AFTRFUNC BCC FMDRVRTN ;(c) = 0 = no errors.
l LDA RTNCODFM ;Get error code from FM parameter list.
l CMP #$5 ;End-of-data error?
l (A6B2) BEQ TOAPPTCH ;Yes - not handled like other errors.
l ;File ends at a full data sec and so we
l ;encountered a zeroed-out T/S link or a
l ;zeroed-out data pair (trk sec vals for
l ;next data sec listed in T/S list).
l (A6B4) JMP OTHRERR ;Only take if got an error other than
l ;an end-of-data error. (See dis'mbly
l (A6B7) ;of errors.)
l TOAPPTCH JMP APNDPTCH ;(See dis'mbly of errors.)
l ------------
l (A6BA) NOP
l BK2FMDRV JSR CKIFAPND ; <----- Note: APNDPTCH returns here.
l (A6BB)
l
l * Check if doing Append command.
l (BA69)
l CKIFAPND LDX CMDINDEX ;Get command index.
l CPX #$1C ;Are we APPENDing?
l BEQ RTNCKAPN ;Yes - leave flag on.
l LDX #0 ;No - turn off append flag.
l STX APPNDFLG
l RTNCKAPN RTS
l (BA75)
l
l (A6BE) LDX #0 ;Zero out the one-data-byte buffer in FM parm list.
l STX ONEIOBUF ;(Also referred to as low byte of CURIOBUF.)
l FMDRVRTN RTS
l (A6C3)
l
l (A699) LDA ONEIOBUF ;Load (a) with byte just read.
l (A69C) RTS
l
l (A633) BNE NOTEND ;If byte read < > 0, then haven't hit
l ...........---------- ;end-of-file marker (eof) yet, so more
l . ;bytes to read.
l . (A635) JSR CLOSEONE ;Ran out of data, so go close file.
l . ;(See routine given in formatted
l . ;dis'mbly of CMDCLOSE.)
l . (A638) LDA #3 ;Using condition 3? (That is, handling
l . CMP OPUTCOND ;an INPUT statement?)
l . (A63D) BEQ DONEPOSN ;Yes - just go to an "RTS".
l . .....------------
l . .
l . .
l . ---->>> Return to INPTNOXC to GET INPUT FROM THE KEYBOARD after encountering out-of-data error >>>------.
l . .
l . .
l . .
l . (A60D) .
l . DONEPOSN RTS
l . ===
l . (A644) (9EA6)
l ..NOTEND CMP #$E0 ;Lowercase? INPTNOXC LDA #3 ;SET CONDITION 3 to
l BCC SAVIT ;Branch if using uppercase. (9EA8) STA OPUTCOND ;signal that we
l (A648) AND #$7F ;Convert lower to upper in order to ;want to process
l (A64A) ;fool the CAPTST routine in monitor ROM. ;input information.
l SAVIT STA ASAVED ;Save char read. (9EAB) JSR RESTOREG
l LDX XSAVED ;Get index to input buffer.
l BEQ TOEXIT ;Branch if first char. * Restore regs.
l DEX ;Turn hi bit on in previous char (9FBA)
l LDA BUF200,X ;stored in BUF200 to convert to RESTOREG LDA ASAVED
l ORA #$80 ;lowercase if necessary. LDY YSAVED
l STA BUF200,X LDX XSAVED
l TOEXIT JMP DOSEXIT ;Go to DOS's exit routine. SEC
l (A65B) ----------- (9FC4) RTS
l
l * Routine to exit DOS. (9EAE) JSR TOTRUIN
l (9FB3)
l DOSEXIT JSR INITIOHK * Go to the true
l * input handler.
l * Initialize the I/O hooks (9EBA)
l * so that DOS intercepts TOTRUIN JMP (KSW)
l * all input & output.
l (A851) * Increment the
l INITIOHK . * random # locs
l . * & GET CODE OF
l (See dis'mbly above.) * THE KEY PRESSED.
l . (FD1B)
l . KEYIN INC RNDL
l (RTS) BNE KEYIN2
l INC RNDH
l (9FB6) LDX STKSAVED ;Restore the stack pointer. KEYIN2 BIT KBD
l TXS BPL KEYIN
l RESTOREG LDA ASAVED ;Restore registers. STA (BASL),Y
l LDY YSAVED LDA KBD
l LDX XSAVED BIT KBDSTRB
l SEC ;Why????? (FD2E) RTS
l (9FC4) RTS ;RETURN TO THE ROUTINE THAT
l ============ ;CALLED THE ROUTINE THAT (9EB1) STA ASAVED ;SAVE CHAR JUST READ.
l ;CONTAINED THE "JSR PREP4DOS" (9EB4) STX XSAVED ;SAVE INDEX TO INPUT
l ;INSTRUCTION (ie. so return to $FD38). ;BUFFER.
l (9EB7) JMP DOSEXIT
l ------------
l
------> When no errors, returns to $FD38 by resetting the stack ----->. * Routine to exit DOS.
. (9FB3)
. DOSEXIT JSR INITIOHK
.
. * Initialize I/O hks
. * so DOS intercepts
. * all input & output.
. (A851)
. INITIOHK .
. .
. (See dis'mbly above.)
. .
. .
. (RTS)
.
. (9FB6) LDX STKSAVED ;Restore stk pointer.
. TXS
. RESTOREG LDA ASAVED ;Restore registers.
. LDY YSAVED
. LDX XSAVED
. SEC ;Why?????
. (9FC4) RTS ;RETURN TO THE ROUTINE
. ============ ;THAT CALLED THE
. ;ROUTINE THAT
. ;CONTAINED THE
. ;"JSR PREP4DOS"
. ;INSTRUCTION. (In this
. ;case, goes to $FD38.)
.
(FD38) CMP #$9B ;Was the escape key pressed?
BEQ ESC ;Yes - go handle escape.
(FD3C) RTS
(FD78) CMP #$95 ;Was char a ctrl-U (right arrow)?
BNE CAPTST ;No.
(FD7C) LDA (BASL),Y ;Yes - prepare to put the original image
; of char in the next screen pos'n
(FD7E) ; back on the screen.
CAPTST CMP #$E0 ;Was char lower case?
BCC ADDINP ;No - go put new char in the input buffer.
AND #$DF ;Convert lower case to upper case.
ADDINP STA BUFF200,X ;Put char in the input buffer.
CMP #$8D ;Was char input a <cr>?
(FD89) BNE NOTCR ;Branch if char wasn't a <cr>.
* A <cr> denoting the end of the input
* string was read from the exec file.
(FD8B) JSR CLREOL
* Clear to the end of the line.
(FC9C)
CLREOL LDY CH ;(y) = next char's screen position.
CLEOLZ LDA #" " ;(a) = space to blank out line.
CLEOL2 STA (BASL),Y ;Put blanks on screen from the next
INY ;char position to the end of the screen
CPY WNDWDTH ;line (as determined by WNDWDTH).
BCC CLEOL2
(FCA7) RTS
(FD8E)
CROUT LDA #$8D ;Set (a) = carriage return.
(FD90) BNE COUT ;ALWAYS.
(FDED)
COUT JMP (CSW)
------------
* DOS's output intercept routine.
(9EBD)
OPUTINCP JSR PREP4DOS
* Prepare for processing by DOS.
* Save the registers & stack pointer.
* Restore the I/O hooks to point to the
* true I/O handlers, ex:
* KSWTRUE: KEYIN --> KSW: KEYIN.
* CSWTRUE: COUT1 --> CSW: COUT1.
(9ED1)
PREP4DOS STA ASAVED ;Save (a), (y) & (x) registers.
STX XSAVED
STY YSAVED
TSX ;Adjust stack ptr & save it so when we
INX ;later restore it and then hit an "RTS"
INX ;instruction, we will return to the
(9EDD) STX STKSAVED ;ROUTINE THAT CALLED THE ROUTINE THAT
;CONTAINED THE "JSR PREP4DOS" INSTRUC.
;(In this case, set saved stk pointer
;so can later return to $FD78.)
* Handy entry point frequently used by
* assembly language programmers to disconnect
* DOS completely.
(9EE0)
UNCONDOS LDX #3
SETRUHKS LDA CSWTRUE,X ;Restore the I/O
STA CSW,X ;hooks 2 pt 2 the
DEX ;true I/O handlers.
BPL SETRUHKS ;4 bytes to move
(9EEA) RTS ;(0 to 3).
* 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 tbl of entry pt addrs.
LDA OUTHNDTB+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 ;Get char to be printed.
(9ED0) RTS ;Execute the "stack jump".
.
.
STACK JUMP TO OPUTHDL3
.
.
* Output handler 3.
*(PROCESS THE INPUT INFORMATION.)
(9F2F)
OPUTHDL3 LDX #0 ;SET CONDITION 0 when input ends.
STX OPUTCOND
CMP #$8D ;Was char an input-terminating <cr>?
(9F36) BEQ ASUMIMED ;Yes.
(9F3F)
ASUMIMED PHA ;Save character on the stack.
(9F40) SEC ;(c) = 1, default condition to assume we
;are presently in the immediate mode.
(9F41) LDA EXECFLAG ;Check if we are EXECing.
(9F44) BNE TESTMODE ;Branch if we are EXECing.
(9F49)
TESTMODE PLA ;Retrieve char from the stack.
(9F4A) BCC TESTEXEC ;Branch if basic is running.
;(c) = 0 = either basic running.
;(c) = 1 = immediate mode or EXECing.
* EXECing or in immediate mode.
(9F4C) LDX XSAVED ;Retrieve index to the input buffer.
(9F4F) JMP PUTINBUF ;Go put char in input buf (CONDITION 1).
------------
* Put char in the input buffer and then
* go display char or else go parse the cmd.
(9F15)
PUTINBUF STA BUF200,X ;Put char in the input buffer.
INX ;Kick up index to the next buffer pos'n.
STX NDX2INBF
CMP #$8D ;Was char a carriage return?
BNE DSPLYCMD ;No.
(9F20) JMP PARSECMD ;Yes - got end of input, so now go
----------- ;and see if it is a DOS command.
* Input character was not a carriage return.
(FD3D)
NOTCR LDA INVFLG ;Save current inverse flag on stack.
PHA
LDA #$FF ;Set inverse flag to normal.
STA INVFLG
LDA BUF200,X ;Get char to be printed.
(FD47) JSR COUT
(FDED)
COUT JMP (CSW) ;Output hk pts to DOS's output handler.
------------
* DOS's output intercept routine.
(9EBD)
OPUTINCP JSR PREP4DOS
* Prepare for processing by DOS.
* Save the registers & stack pointer.
* Restore the I/O hooks to point to the
* true I/O handlers, ex:
* KSWTRUE: KEYIN --> KSW: KEYIN.
* CSWTRUE: COUT1 --> CSW: COUT1.
(9ED1)
PREP4DOS STA ASAVED ;Save (a), (y) & (x)
STX XSAVED ;registers.
STY YSAVED
TSX ;Adjust stack ptr &
INX ;save it so that
INX ;when we later
(9EDD) STX STKSAVED ;restore it and hit
;an "RTS", we can
;return to routine
;that called the
;routine that
;contained the
;"JSR PREP4DOS"
;instruction.
;(In this case,
;set saved stk ptr
;2 return 2 $FD4A.)
* Restore the I/O hooks to point to the
* true I/O handlers, ex:
* KSWTRUE: KEYIN --> KSW: KEYIN.
* CSWTRUE: COUT1 --> CSW: COUT1.
(9EE0)
UNCONDOS LDX #3
SETRUHKS LDA CSWTRUE,X ;Restore the I/O
STA CSW,X ;hooks 2 pt 2 the
DEX ;true I/O handlers.
BPL SETRUHKS ;4 bytes to move
(9EEA) RTS ;(0 to 3).
* 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 tbl of entry pt addrs.
LDA OUTHNDTB+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 ;Get char to be printed.
(9ED0) RTS ;Execute the "stack jump".
.
.
STACK JUMP TO OPUTHDL3
.
.
* Output handler 3.
*(PROCESS THE INPUT INFORMATION.)
(9F2F)
OPUTHDL3 LDX #0 ;SET CONDITION 0 when input ends.
STX OPUTCOND
CMP #$8D ;Was char an input-terminating <cr>?
(9F36) BEQ ASUMIMED ;Yes.
* Char was not a carriage return.
(9F38)
TESTEXEC LDA EXECFLAG ;Are we EXECing?
BEQ DSPLYALL ;No.
(9F3D) BNE DSPLYINP ;Yes - flag contains first char of the
;name of the exec file.
* Display input conditionally.
(9F9D)
DSPLYINP LDA #%00100000 ;Set bit5 so see if using "MONI".
DSPLYCHR AND CIOCUMUL ;Test flag - see if should display.
(9FA2) BEQ DOSEXIT ;Take branch if don't want to display.
;(Specific bit was off. MON/NOMON cleared
;or set the specific bit.)
* Display the char.
(9FA4)
DSPLYALL JSR RESTOREG
* Restore (a), (y) & (x) registers.
(9FBA)
RESTOREG LDA ASAVED
LDY YSAVED
LDX XSAVED
SEC ;Why?????
(9FC4) RTS
(9FA7) JSR GODSPLY
(9FC5)
GODSPLY JMP (CSW)
------------
* PRINT INPUT CHAR THROUGH
* THE TRUE OUTPUT HANDLER.
(FDF0)
COUT1 .
.
(See dis'mbly in APPLE II REFERENCE MANUAL.)
.
.
(RTS)
* Save registers and reset hooks.
(9FAA) STA ASAVED ;Save (a), (y) & (x) registers.
STY YSAVED
(9FB0) STX XSAVED
* Routine to exit DOS.
(9FB3)
DOSEXIT JSR INITIOHK ;Reset DOS hooks.
* 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
* rout'n that refers 2 "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 input hk needs 2 be reset.
(A851)
INITIOHK LDA KSW+1
CMP ADINPTCP+1
(A856) BEQ CKOUTHK ;Input hk already
;pts 2 DOS's input
;handler, so go chk
;the oputput hook.
* Save true input hook and then reset
* the input hook to point to DOS.
* (KSW: KEYIN --> KSWTRUE: KEYIN)
* (ADINPTCP: INPTINCP --> KSW: INPTINCP)
(A858) STA KSWTRUE+1
LDA KSW
STA KSWTRUE
LDA ADINPTCP
STA KSW
LDA ADINPTCP+1
(A868) STA KSW+1
* Check if output hk needs 2 be reset.
(A86A)
CKOUTHK LDA CSW+1
CMP ADOPUTCP+1
(A86F) BEQ SETHKRTN ;Output hk already
;points to DOS's
;output handler,
;so go exit.
* Save true output hook and then reset
* the output hook to point to DOS.
* (CSW: COUT1 --> CSWTRUE: COUT1)
* (ADOPUTCP: OPUTINCP --> CSW: OPUTINCP)
(A871) STA CSWTRUE+1
LDA CSW
STA CSWTRUE
LDA ADOPUTCP
STA CSW
LDA ADOPUTCP+1
STA CSW+1
SETHKRTN RTS
(A883)
* Reset stack pointer & save registers.
(9FB6) LDX STKSAVED ;Retrieve the saved stack pointer value
TXS ;& reset the stack to return to caller.
RESTOREG LDA ASAVED ;Restore (a), (y) & (x) registers.
LDY YSAVED
LDX XSAVED
SEC ;Return to routine that called routine
(9FC4) RTS ;that contained "JSR PREP4DOS" instruc.
(FD4A) PLA ;Restore the original contents of the
STA INVFLG ;inverse flag.
LDA BUF200,X ;(a) = char that was input.
CMP #$88 ;Was char a backspace?
BEQ BCKSPC ;Yes.
CMP #$98 ;Was char a ctrl-X (cancel char)?
BEQ CANCEL ;Yes.
CPX #$F8 ;Input 249 (0 to 248) chars yet?
BCC NOTCR1 ;No.
JSR BELL ;Yes - go ring the warning bell.
NOTCR1 INX ;Increase the input character counter.
(FD60) BNE NXTCHAR ;Character counter hasn't wrapped around
(FD62) . ;to zero yet, so go get next char.
CANCEL . ;Too many chrs were input, so go cancel
. ;the input line.
.
============
.
.
.
********************************************************
* *
* See disassembly titled "DOSCMDPARSING&PROCESSING". *
* *
*------------------------------------------------------*
* *
* - parses and executes the command. *
* - or adds an Applesoft program line. *
* - or generates a syntax-error message. *
* - On entry, an image of the stack pointer has *
* been adjusted and saved (to be later used to *
* cause execution to return to $D533 after the *
* command is executed). Eventually execution *
* flows back into the RESTART ($D43C) routine. *
* *
********************************************************
.
.
(9FCD) .
PARSECMD .
.
.