ref: 74dfb591e159b5d4600e34dc736a611b2f4a11ba
dir: /sys/src/ape/lib/ap/gen/strcspn.c/
#include <string.h> #define N 256 size_t strcspn(const char *s, const char *b) { char map[N], *os; memset(map, 0, N); for(;;) { map[*(unsigned char*)b] = 1; if(*b++ == 0) break; } os = (char*)s; while(map[*(unsigned char*)s++] == 0) ; return s - os - 1; }