ref: dcaa2fe00e130bbfbbb1e278cd8b3308c2dfd1a9
dir: /src/libc/stdlib/_dtoi.c/
#include <ctype.h> #include <limits.h> #include <string.h> int _dtoi(char c) { static const char digits[] = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ"; char *p; if (p = strchr(digits, toupper(c))) return p - digits; return INT_MAX; }