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