; mainargs.s
;
; 2003-03-07, Ullrich von Bassewitz,
;   based on code from Stefan A. Haubenthal, <polluks@web.de>
; 2005-02-26, Ullrich von Bassewitz
; 2014-09-10, Greg King
;
; 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
        .import         sys_bank, restore_bank
        .import         sysp0:zp, ptr1:zp

        .include        "cbm510.inc"
        .macpack        generic


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.
; Because the buffer, that we're copying into, was zeroed out,
; we don't need to add a NUL character.
;
        jsr     sys_bank
        ldy     #FNAM
        lda     (sysp0),y       ; Get file-name pointer from system bank
        sta     ptr1
        iny
        lda     (sysp0),y
        sta     ptr1+1
        iny                     ; FNAM_BANK
        lda     (sysp0),y
        tax
        ldy     #FNAM_LEN
        lda     (sysp0),y
        tay
        lda     #0              ; The terminating NUL character
        stx     IndReg          ; Look for name in correct bank
        cpy     #NAME_LEN + 1
        blt     L1
        ldy     #NAME_LEN       ; Limit the length
        bne     L1              ; Branch always
L0:     lda     (ptr1),y
L1:     sta     name,y
        dey
        bpl     L0
        jsr     restore_bank
        inc     __argc          ; argc always is equal to at least 1

; Find a "rem" token.

        ldx     #0
L2:     lda     BASIC_BUF,x
        bze     done            ; No "rem," no args.
        inx
        cmp     #REM
        bne     L2
        ldy     #1 * 2

; Find the next argument.

next:   lda     BASIC_BUF,x
        bze     done            ; End of line reached
        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. That is useful because we
; will check now for a quoted argument; in which case, we will have to skip that
; 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.

        txa                     ; Get low byte
        add     #<BASIC_BUF
        sta     argv,y          ; argv[y]= &arg
        lda     #>$0000
        adc     #>BASIC_BUF
        sta     argv+1,y
        iny
        iny
        inc     __argc          ; Found another arg

; Search for the end of the argument.

argloop:lda     BASIC_BUF,x
        bze     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     #$00
        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?
        blt     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

.segment        "INIT"

term:   .res    1
name:   .res    NAME_LEN + 1

.data

; char* argv[MAXARGS+1]={name};
argv:   .addr   name
        .res    MAXARGS * 2