Created
January 21, 2023 16:47
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| /* SPDX-License-Identifier: BSD-2-Clause */ | |
| /* Copyright (c), 2023, KanOS Contributors */ | |
| #include <kan/utf8.h> | |
| #include <stdlib.h> | |
| size_t mbtowc(wchar_t *restrict wc, const char *restrict s, size_t n) | |
| { | |
| size_t i, j; | |
| size_t nchar; | |
| wchar_t twc; | |
| if(!s || !s[0]) { | |
| /* If I were to implement something | |
| * like mbstate_t, at this point it | |
| * should be reset (cppreference). */ | |
| return 0; | |
| } | |
| j = 0; | |
| nchar = 0; | |
| twc = 0; | |
| for(i = 0; s[i] && (i < n); i++) { | |
| if(utf8_is_single_byte(s[i])) { | |
| if(wc) | |
| wc[0] = utf8_get_single_bits(s[i]); | |
| return 1; | |
| } | |
| if(utf8_is_double_byte(s[i])) { | |
| twc = utf8_get_double_bits(s[i]); | |
| nchar = 2; | |
| j = nchar; | |
| continue; | |
| } | |
| if(utf8_is_triple_byte(s[i])) { | |
| twc = utf8_get_triple_bits(s[i]); | |
| nchar = 3; | |
| j = nchar; | |
| continue; | |
| } | |
| if(utf8_is_quadruple_byte(s[i])) { | |
| twc = utf8_get_quadruple_bits(s[i]); | |
| nchar = 4; | |
| j = nchar; | |
| continue; | |
| } | |
| if(utf8_is_continuation_byte(s[i]) && nchar) { | |
| twc <<= utf8_continuation_shift; | |
| twc |= utf8_get_continuation_bits(s[i]); | |
| if(--j == 1) | |
| break; | |
| continue; | |
| } | |
| return SIZE_MAX; | |
| } | |
| if(j == 1) { | |
| if(wc) | |
| wc[0] = twc; | |
| return nchar; | |
| } | |
| return SIZE_MAX; | |
| } |
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