-U_CFUNC int32_t
-u_writeIdenticalLevelRun(const UChar *s, int32_t length, uint8_t *p);
-
-U_CFUNC int32_t
-u_writeIdenticalLevelRunTwoChars(UChar32 first, UChar32 second, uint8_t *p);
-
-U_CFUNC int32_t
-u_lengthOfIdenticalLevelRun(const UChar *s, int32_t length);
-
-U_CFUNC uint8_t *
-u_writeDiff(int32_t diff, uint8_t *p);
+U_CFUNC UChar32
+u_writeIdenticalLevelRun(UChar32 prev, const UChar *s, int32_t length, icu::ByteSink &sink);