1
0
mirror of https://github.com/cc65/cc65.git synced 2024-12-24 11:31:31 +00:00
cc65/libsrc/c16/mainargs.s
Oliver Schmidt 0ee9b2e446 Changed run location of INIT segment.
So far the INIT segment was run from the later heap+stack. Now the INIT segment is run from the later BSS. The background is that so far the INIT segment was pretty small (from $80 to $180 bytes). But upcoming changes will increase the INIT segment in certain scenarios up to ~ $1000 bytes. So programs with very limited heap+stack might just not been able to move the INIT segment to its run location. But moving the INIT segment to the later BSS allows it to occupy the later BSS+heap+stack.

In order to allow that the constructors are _NOT_ allowed anymore to access the BSS. Rather they must use the DATA segment or the new INITBSS segment. The latter isn't cleared at any point so the constructors may use it to expose values to the main program. However they must make sure to always write the values as they are not pre-initialized.
2015-10-14 22:52:09 +02:00

139 lines
4.1 KiB
ArmAsm

; 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
;
; 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 "plus4.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 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 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 ; Vector address
jsr FETCH ; Load byte from RAM
L1: sta name,y
dey
bpl L0
inc __argc ; argc always is equal to, at least, 1
; Find the "rem" token.
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
next: lda BASIC_BUF,x
beq 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. 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
.segment "INITBSS"
term: .res 1
name: .res NAME_LEN + 1
.data
; char* argv[MAXARGS+1]={name};
argv: .addr name
.res MAXARGS * 2