63 lines
1.7 KiB
C
63 lines
1.7 KiB
C
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// SPDX-License-Identifier: LGPL-3.0-or-later
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/**
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* \file utf/utfrrune.c
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*
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* Implements `utfrrune()`.
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*
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* \copyright The DoubleFourteen Code Forge (C) All Rights Reserved
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* \author Lorenzo Cogotti
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*/
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/*
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* This work is derived from Plan 9 libutf, see utf/utf.h for details.
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* Original license terms follow:
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*
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* The authors of this software are Rob Pike and Ken Thompson.
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* Copyright (c) 2002 by Lucent Technologies.
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* Permission to use, copy, modify, and distribute this software for any
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* purpose without fee is hereby granted, provided that this entire notice
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* is included in all copies of any software which is or includes a copy
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* or modification of this software and in all copies of the supporting
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* documentation for such software.
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* THIS SOFTWARE IS BEING PROVIDED "AS IS", WITHOUT ANY EXPRESS OR IMPLIED
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* WARRANTY. IN PARTICULAR, NEITHER THE AUTHORS NOR LUCENT TECHNOLOGIES MAKE
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* ANY REPRESENTATION OR WARRANTY OF ANY KIND CONCERNING THE MERCHANTABILITY
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* OF THIS SOFTWARE OR ITS FITNESS FOR ANY PARTICULAR PURPOSE.
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*
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* The original libutf library is available at: https://9fans.github.io/plan9port/unix/libutf.tgz
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*/
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#include "utf/utf.h"
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#include <string.h>
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char *utfrrune(const char *s, Rune c)
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{
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if (c < RUNE_SYNC)
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return strrchr(s, c);
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char *s1 = NULL;
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while (TRUE) {
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Rune c1 = *(const Uint8 *) s;
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if (c1 < RUNE_SELF) { // one byte rune
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if (c1 == '\0')
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break;
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if (RUNE_SYNC != RUNE_SELF && c1 == c) // exposition only, optimized away, see topmost if ()
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s1 = (char *) s;
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s++;
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continue;
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}
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Rune r;
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size_t n = chartorune(&r, s);
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if (r == c)
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s1 = (char *) s;
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s += n;
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}
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return s1;
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}
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