ref: 8188b4f4f0e07b6669e6ae3c6c1099af917eaab4
dir: /sys/src/libc/port/strcspn.c/
#include <u.h> #include <libc.h> #define N 256 long strcspn(char *s, char *b) { char map[N], *os; memset(map, 0, N); for(;;) { map[*(uchar*)b] = 1; if(*b++ == 0) break; } os = s; while(map[*(uchar*)s++] == 0) ; return s - os - 1; }