ref: ea413b4a62be9993e4b63bf237f0b1d482f4aafa
dir: /sys/src/ape/lib/ap/gen/strspn.c/
#include <string.h> #define N 256 size_t strspn(const char *s, const char *b) { char map[N], *os; memset(map, 0, N); while(*b) map[*(unsigned char *)b++] = 1; os = s; while(map[*(unsigned char *)s++]) ; return s - os - 1; }