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The starting point is the CALL2051:REM <cmdline> approach. It uses the BASIC input buffer at $200. ProDOS stores the name of the loaded program at $280 (which we want for argv[0]) leaving us with 128 char buffer. If we run the program via exec() we don't need the CALL2051 but only the REM token (which is just one char). So have a maximum cmdline length of 126 (plus a terminating zero). There's no specification for ProDOS BIN file cmdline parameters so exec() just supports the CALL2051:REM <cmdline> approach. In contrast ProDOS SYS files allow for a 'startup filename'. A ProDOS filename is short than 126 chars so having exec() general cut the cmdline after 126 chars seems reasonable. If the SYS file we exec() allows for less we cut the cmdline further. Our 'loader.system' SYS file however allows for an unusually 126 char long "startup filename" as it is targeted towards cc65 BIN porgrams with their 126 cmdline length.
180 lines
5.5 KiB
ArmAsm
180 lines
5.5 KiB
ArmAsm
; mainargs.s
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;
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; Ullrich von Bassewitz, 2003-03-07
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; Based on code from Stefan A. Haubenthal <polluks@web.de>, 2003-11-08
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; Greg King, 2003-05-18
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; Stefan Haubenthal, 2005-01-07
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; Oliver Schmidt, 2005-04-05
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;
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; Scan a group of arguments that are in BASIC's input-buffer.
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; Build an array that points to the beginning of each argument.
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; Send, to main(), that array and the count of the arguments.
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; Command-lines look like these lines:
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;
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; call2051
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; call2051 : rem
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; call2051:rem arg1 " arg 2 is quoted " arg3 "" arg5
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;
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; "call" and "rem" are entokenned; the args. are not. Leading and trailing
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; spaces outside of quotes are ignored.
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; TO-DO:
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; Add a control-character quoting mechanism.
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.constructor initmainargs, 24
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.import __argc, __argv, __dos_type
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.include "zeropage.inc"
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.include "apple2.inc"
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; Maximum number of arguments allowed in the argument table.
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; (An argument contains a comma, at least.)
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MAXARGS = 10
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; ProDOS stores the filename in the second half of BASIC's input buffer, so
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; there are 128 characters left. At least 1 character is necessary for the
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; REM so 127 characters (including the terminating zero) may be used before
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; overwriting the ProDOS filename. As we don't want to further restrict the
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; command-line length we reserve those 127 characters.
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BUF_LEN = 127
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BASIC_BUF = $200
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FNAM_LEN = $280
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FNAM = $281
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REM = $B2 ; BASIC token-code
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; Get possible command-line arguments. Goes into the special INIT segment,
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; which may be reused after the startup code is run.
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.segment "INIT"
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initmainargs:
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; Assume that the program was loaded, a moment ago, by the traditional BLOAD
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; statement of BASIC.SYSTEM. Save the filename as argument #0 if available.
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ldx __dos_type ; No ProDOS -> argv[0] = ""
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beq :+
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; Terminate the filename with a zero to make it a valid C string.
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ldx FNAM_LEN
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: lda #$00
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sta FNAM,x
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inc __argc ; argc always is equal to, at least, 1
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; Find the "rem" token.
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ldx #$00
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: lda BASIC_BUF,x
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beq done ; No "rem" -> no args
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inx
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cmp #REM
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bne :-
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; If a clock is present it is called by ProDOS on file operations. On machines
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; with a slot-based clock (like the Thunder Clock) the clock firmware places
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; the current date in BASIC's input buffer. Therefore we have to create a copy
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; of the command-line in a different buffer before the original is potentially
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; destroyed.
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ldy #$00
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: lda BASIC_BUF,x
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sta buffer,y
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inx
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iny
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cpy #BUF_LEN - 1 ; Keep the terminating zero intact
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bcc :-
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; Start processing the arguments.
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ldx #$00
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ldy #$01 * 2 ; Start with argv[1]
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; Find the next argument. Stop if the end of the string or a character with the
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; hibit set is reached. The later is true if the string isn't already parsed by
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; BASIC (as expected) but is a still unprocessed input string. In this case the
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; string isn't the expected command-line at all. We found this out the hard way
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; by BRUNing the program with ProDOS on a machine with a slot-based clock (like
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; the Thunder Clock). ProDOS called the clock firmware which places the current
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; date as BASIC input string with hibits set in the input buffer. While looking
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; for the REM token we stumbled across the first '2' character ($32+$80 = $B2)
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; and interpreted the rest of the date as a spurious command-line parameter.
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next: lda buffer,x
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beq done
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bmi done
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inx
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cmp #' ' ; Skip leading spaces
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beq next
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; Found start of next argument. We've incremented the pointer in X already, so
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; it points to the second character of the argument. This is useful since we
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; will check now for a quoted argument, in which case we will have to skip this
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; first character.
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cmp #'"' ; Is the argument quoted?
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beq :+ ; Jump if so
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dex ; Reset pointer to first argument character
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lda #' ' ; A space ends the argument
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: sta tmp1 ; Set end of argument marker
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; Now store a pointer to the argument into the next slot.
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txa ; Get low byte
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clc
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adc #<buffer
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sta argv,y ; argv[y] = &arg
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iny
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lda #$00
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adc #>buffer
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sta argv,y
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iny
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inc __argc ; Found another arg
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; Search for the end of the argument.
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: lda buffer,x
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beq done
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inx
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cmp tmp1
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bne :-
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; We've found the end of the argument. X points one character behind it, and
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; A contains the terminating character. To make the argument a valid C string,
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; replace the terminating character by a zero.
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lda #$00
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sta buffer-1,x
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; Check if the maximum number of command-line arguments is reached. If not,
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; parse the next one.
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lda __argc ; Get low byte of argument count
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cmp #MAXARGS ; Maximum number of arguments reached?
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bcc next ; Parse next one if not
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; (The last vector in argv[] already is NULL.)
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done: lda #<argv
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ldx #>argv
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sta __argv
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stx __argv+1
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rts
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; This array is zeroed before initmainargs is called.
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; char* argv[MAXARGS+1] = {FNAM};
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.data
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argv: .addr FNAM
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.res MAXARGS * 2
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.bss
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buffer: .res BUF_LEN
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