+; mainargs.s
;
; Ullrich von Bassewitz, 2003-03-07
+; Based on code from Stefan A. Haubenthal <polluks@web.de>, 2003-11-08
+; Greg King, 2003-05-18
+; Stefan Haubenthal, 2005-01-07
+; Oliver Schmidt, 2005-04-05
;
-; Setup arguments for main
+; Scan a group of arguments that are in BASIC's input-buffer.
+; Build an array that points to the beginning of each argument.
+; Send, to main(), that array and the count of the arguments.
+
+; Command-lines look like these lines:
+;
+; call2051
+; call2051 : rem
+; call2051:rem arg1 " arg 2 is quoted " arg3 "" arg5
;
+; "call" and "rem" are entokenned; the args. are not. Leading and trailing
+; spaces outside of quotes are ignored.
+
+; TO-DO:
+; Add a control-character quoting mechanism.
+
+ .constructor initmainargs, 18
+ .import __argc, __argv, __dos_type
+
+ .include "zeropage.inc"
+ .include "apple2.inc"
+
+; Maximum number of arguments allowed in the argument table.
+; (An argument contains a comma, at least.)
+
+MAXARGS = 10
+
+; ProDOS stores the filename in the second half of BASIC's input buffer, so
+; there are 128 characters left. At least 7 characters are necessary for the
+; CALLxxxx:REM so 121 characters may be used before overwriting the ProDOS
+; filename. As we don't want to put further restrictions on the command-line
+; length we reserve those 121 characters terminated by a zero.
+
+BUF_LEN = 122
+
+BASIC_BUF = $200
+FNAM_LEN = $280
+FNAM = $281
+REM = $B2 ; BASIC token-code
+
+; Get possible command-line arguments. Goes into the special INIT segment,
+; which may be reused after the startup code is run.
+
+ .segment "INIT"
+
+initmainargs:
+
+; Assume that the program was loaded, a moment ago, by the traditional BLOAD
+; statement of BASIC.SYSTEM. Save the filename as argument #0 if available.
+
+ ldx __dos_type ; No ProDOS -> argv[0] = ""
+ beq :+
+
+; Terminate the filename with a zero to make it a valid C string.
+
+ ldx FNAM_LEN
+: lda #$00
+ sta FNAM,x
+ inc __argc ; argc always is equal to, at least, 1
- .constructor initmainargs, 24
- .import __argc, __argv
+; Find the "rem" token.
+ ldx #$00
+: lda BASIC_BUF,x
+ beq done ; No "rem" -> no args
+ inx
+ cmp #REM
+ bne :-
-;---------------------------------------------------------------------------
-; Setup arguments for main
+; If a clock is present it is called by ProDOS on file operations. On machines
+; with a slot-based clock (like the Thunder Clock) the clock firmware places
+; the current date in BASIC's input buffer. Therefore we have to create a copy
+; of the command-line in a different buffer before the original is potentially
+; destroyed.
-.proc initmainargs
+ ldy #$00
+: lda BASIC_BUF,x
+ sta buffer,y
+ inx
+ iny
+ cpy #BUF_LEN - 1 ; Keep the terminating zero intact
+ bcc :-
+; Start processing the arguments.
+
+ ldx #$00
+ ldy #$01 * 2 ; Start with argv[1]
+
+; Find the next argument. Stop if the end of the string or a character with the
+; hibit set is reached. The later is true if the string isn't already parsed by
+; BASIC (as expected) but is a still unprocessed input string. In this case the
+; string isn't the expected command-line at all. We found this out the hard way
+; by BRUNing the program with ProDOS on a machine with a slot-based clock (like
+; the Thunder Clock). ProDOS called the clock firmware which places the current
+; date as BASIC input string with hibits set in the input buffer. While looking
+; for the REM token we stumbled across the first '2' character ($32+$80 = $B2)
+; and interpreted the rest of the date as a spurious command-line parameter.
+
+next: lda buffer,x
+ beq done
+ bmi done
+ inx
+ cmp #' ' ; Skip leading spaces
+ beq next
+
+; Found start of next argument. We've incremented the pointer in X already, so
+; it points to the second character of the argument. This is useful since we
+; will check now for a quoted argument, in which case we will have to skip this
+; first character.
+
+ cmp #'"' ; Is the argument quoted?
+ beq :+ ; Jump if so
+ dex ; Reset pointer to first argument character
+ lda #' ' ; A space ends the argument
+: sta tmp1 ; Set end of argument marker
+
+; Now store a pointer to the argument into the next slot.
+
+ txa ; Get low byte
+ clc
+ adc #<buffer
+ sta argv,y ; argv[y] = &arg
+ iny
+ lda #$00
+ adc #>buffer
+ sta argv,y
+ iny
+ inc __argc ; Found another arg
+
+; Search for the end of the argument.
+
+: lda buffer,x
+ beq done
+ inx
+ cmp tmp1
+ bne :-
+
+; We've found the end of the argument. X points one character behind it, and
+; A contains the terminating character. To make the argument a valid C string,
+; replace the terminating character by a zero.
+
+ lda #$00
+ sta buffer-1,x
+
+; Check if the maximum number of command-line arguments is reached. If not,
+; parse the next one.
+
+ lda __argc ; Get low byte of argument count
+ cmp #MAXARGS ; Maximum number of arguments reached?
+ bcc next ; Parse next one if not
+
+; (The last vector in argv[] already is NULL.)
+
+done: lda #<argv
+ ldx #>argv
+ sta __argv
+ stx __argv+1
rts
-.endproc
+; This array is zeroed before initmainargs is called.
+; char* argv[MAXARGS+1] = {FNAM};
+
+ .data
+
+argv: .addr FNAM
+ .res MAXARGS * 2
+ .bss
+buffer: .res BUF_LEN
\ No newline at end of file
projects / cc65 / blobdiff