+; mainargs.s
;
; Ullrich von Bassewitz, 2003-03-07
+; Based on code from Stefan A. Haubenthal, <polluks@web.de>
+; 2003-05-18, Greg King
+; 2004-04-28, 2005-02-26, Ullrich von Bassewitz
;
-; 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:
+;
+; run
+; run : rem
+; run:rem arg1 " arg 2 is quoted " arg3 "" arg5
+;
+; "run" and "rem" are entokenned; the args. are not. Leading and trailing
+; spaces outside of quotes are ignored.
+;
+; TO-DO:
+; - The "file-name" might be a path-name; don't copy the directory-components.
+; - Add a control-character quoting mechanism.
+
+ .constructor initmainargs, 24
+ .import __argc, __argv
+
+ .include "vic20.inc"
+
+
+MAXARGS = 10 ; Maximum number of arguments allowed
+REM = $8f ; BASIC token-code
+NAME_LEN = 16 ; Maximum length of command-name
+
+; Get possible command-line arguments. Goes into the special ONCE segment,
+; which may be reused after the startup code is run
+
+.segment "ONCE"
+
+initmainargs:
+
+; Assume that the program was loaded, a moment ago, by the traditional LOAD
+; statement. Save the "most-recent filename" as argument #0.
+
+ lda #0 ; The terminating NUL character
+ ldy FNAM_LEN
+ cpy #NAME_LEN + 1
+ bcc L1
+ ldy #NAME_LEN ; Limit the length
+ bne L1 ; Branch always
+L0: lda (FNAM),y
+L1: sta name,y
+ dey
+ bpl L0
+ inc __argc ; argc always is equal to, at least, 1
+; Find the "rem" token.
- .constructor initmainargs, 24
- .import __argc, __argv
+ ldx #0
+L2: lda BASIC_BUF,x
+ beq done ; No "rem," no args.
+ inx
+ cmp #REM
+ bne L2
+ ldy #1 * 2
+; Find the next argument
-;---------------------------------------------------------------------------
-; Setup arguments for main
+next: lda BASIC_BUF,x
+ beq done ; End of line reached
+ inx
+ cmp #' ' ; Skip leading spaces
+ beq next
-.proc initmainargs
+; 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.
+found: cmp #'"' ; Is the argument quoted?
+ beq setterm ; Jump if so
+ dex ; Reset pointer to first argument character
+ lda #' ' ; A space ends the argument
+setterm:sta term ; Set end of argument marker
+
+; Now store a pointer to the argument into the next slot. Since the BASIC
+; input buffer is located at the start of a RAM page, no calculations are
+; necessary.
+
+ txa ; Get low byte
+ sta argv,y ; argv[y]= &arg
+ iny
+ lda #>BASIC_BUF
+ sta argv,y
+ iny
+ inc __argc ; Found another arg
+
+; Search for the end of the argument
+
+argloop:lda BASIC_BUF,x
+ beq done
+ inx
+ cmp term
+ bne argloop
+
+; 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 #0
+ sta BASIC_BUF-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
+.segment "INIT"
+
+term: .res 1
+name: .res NAME_LEN + 1
+.data
+; char* argv[MAXARGS+1]={name};
+argv: .addr name
+ .res MAXARGS * 2
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