ref: e0508d01357b9062eabac8c7fe4cdb6ea7c57fc8
dir: /3rd/utf/utfnlen.c/
#include "platform.h" int utfnlen(const char *s, long m) { int c; long n; Rune rune; const char *es; es = s + m; for(n = 0; s < es; n++) { c = *(uint8_t*)s; if(c < Runeself){ if(c == '\0') break; s++; continue; } if(!fullrune(s, es-s)) break; s += chartorune(&rune, s); } return n; }