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cc65/libsrc/atari/ucase_fn.s

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;
; Christian Groessler, Dec-2001
;
; ucase_fn
; helper routine to convert a string (file name) to uppercase
; used by open.s and remove.s
;
; Calling parameters:
; AX - points to filename
; Return parameters:
; C - 0/1 for OK/Error (filename too long)
; AX - points to uppercased version of the filename on the stack
; tmp3 - amount of bytes used on the stack (needed for cleanup)
; Uses:
; ptr4 - scratch pointer used to remember original AX pointer
;
;
.include "atari.inc"
.importzp tmp3,ptr4,sp
.import _strupr,subysp
.export ucase_fn
ucase_fn: .proc
; we make sure that the filename doesn't contain lowercase letters
; we copy the filename we got onto the stack, uppercase it and use this
; one to open the iocb
; we're using tmp3, ptr4
; save the original pointer
sta ptr4
stx ptr4+1
; now we need the length of the name
ldy #0
loop: lda (ptr4),y
beq str_end
cmp #ATEOL ; we also accept Atari EOF char as end of string
beq str_end
iny
bne loop ; not longer than 255 chars (127 real limit)
toolong:sec ; indicate error
rts
str_end:iny ; room for terminating zero
cpy #128 ; we only can handle lenght < 128
bcs toolong
sty tmp3 ; save size
jsr subysp ; make room on the stack
; copy filename to the temp. place on the stack
lda #0 ; end-of-string
sta (sp),y ; Y still contains length + 1
dey
loop2: lda (ptr4),y
sta (sp),y
dey
bpl loop2 ; bpl: this way we only support a max. length of 127
; uppercase the temp. filename
ldx sp+1
lda sp
jsr _strupr
; leave X and Y pointing to the modified filename
lda sp
ldx sp+1
clc ; indicate success
rts
ucase_fn: .endproc