ref: 21d7790b3b0dde7f2a641d8815f66dec5cef6d2c
dir: /sys/src/ape/lib/ap/gen/memchr.c/
#include <string.h> void* memchr(const void *ap, int c, size_t n) { unsigned char *sp; sp = (unsigned char*)ap; c &= 0xFF; while(n > 0) { if(*sp++ == c) return sp-1; n--; } return 0; }