utfrrune.c 1.6 KB

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  1. /*
  2. * This file is part of the UCB release of Plan 9. It is subject to the license
  3. * terms in the LICENSE file found in the top-level directory of this
  4. * distribution and at http://akaros.cs.berkeley.edu/files/Plan9License. No
  5. * part of the UCB release of Plan 9, including this file, may be copied,
  6. * modified, propagated, or distributed except according to the terms contained
  7. * in the LICENSE file.
  8. */
  9. /*
  10. * The authors of this software are Rob Pike and Ken Thompson.
  11. * Copyright (c) 2002 by Lucent Technologies.
  12. * Permission to use, copy, modify, and distribute this software for any
  13. * purpose without fee is hereby granted, provided that this entire notice
  14. * is included in all copies of any software which is or includes a copy
  15. * or modification of this software and in all copies of the supporting
  16. * documentation for such software.
  17. * THIS SOFTWARE IS BEING PROVIDED "AS IS", WITHOUT ANY EXPRESS OR IMPLIED
  18. * WARRANTY. IN PARTICULAR, NEITHER THE AUTHORS NOR LUCENT TECHNOLOGIES MAKE ANY
  19. * REPRESENTATION OR WARRANTY OF ANY KIND CONCERNING THE MERCHANTABILITY
  20. * OF THIS SOFTWARE OR ITS FITNESS FOR ANY PARTICULAR PURPOSE.
  21. */
  22. #include <stdarg.h>
  23. #include <string.h>
  24. #include "utf.h"
  25. #include "utfdef.h"
  26. char*
  27. utfrrune(char *s, int32_t c)
  28. {
  29. int32_t c1;
  30. Rune r;
  31. char *s1;
  32. if(c < Runesync) /* not part of utf sequence */
  33. return strrchr(s, c);
  34. s1 = 0;
  35. for(;;) {
  36. c1 = *(uint8_t*)s;
  37. if(c1 < Runeself) { /* one byte rune */
  38. if(c1 == 0)
  39. return s1;
  40. if(c1 == c)
  41. s1 = s;
  42. s++;
  43. continue;
  44. }
  45. c1 = chartorune(&r, s);
  46. if(r == c)
  47. s1 = s;
  48. s += c1;
  49. }
  50. }