2020-04-02 09:15:53 +00:00
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; tolower.s
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2000-05-28 13:40:48 +00:00
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;
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2020-04-02 09:15:53 +00:00
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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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2000-05-28 13:40:48 +00:00
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;
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; int tolower (int c);
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;
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2013-05-09 11:56:54 +00:00
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.export _tolower
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2020-04-02 09:15:53 +00:00
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.include "ctype.inc"
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.import ctype_preprocessor
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2000-05-28 13:40:48 +00:00
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_tolower:
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2020-04-02 09:15:53 +00:00
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tay ; save char
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jsr ctype_preprocessor ; (always clears X)
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bcc @L2 ; out of range?
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@L1: tya ; if so, return the argument unchanged
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rts
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@L2: and #CT_UPPER ; upper case char?
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beq @L1 ; jump if no
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tya ; restore char
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adc #<('a'-'A') ; make lower case char (ctype_preprocessor ensures carry clear)
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rts
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