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|
; ctypemask.s
;
; This file is part of
; cc65 - a freeware C compiler for 6502 based systems
;
; https://cc65.github.io
;
; See "LICENSE" file for legal information.
;
; ctypemask(int c)
;
; converts a character to test via the is*-functions to the matching ctype-masks
; If c is out of the 8-bit range, the function returns with carry set and accu cleared.
; Return value is in accu and x has to be always clear when returning
; (makes calling code shorter)!
;
; IMPORTANT: stricmp, strlower, strnicmp, strupper and atoi rely that Y is not changed
; while calling this function!
;
.export ctypemask
.export ctypemaskdirect
.import __ctype
.import __ctypeidx
ctypemask:
cpx #$00 ; char range ok?
bne SC ; branch if not
ctypemaskdirect:
lsr a
tax
lda __ctypeidx,x
bcc @lowerNibble
@upperNibble:
lsr a
lsr a
lsr a
lsr a
clc ; remove out of bounds flag
@lowerNibble:
and #%00001111
tax
lda __ctype,x
ldx #$00
rts
SC: sec
lda #$00
tax
rts
|
