ref: 5ebb1a29d8250027e8b7f2287f3bfa3a6f3d13ac dir: /sys/src/ape/lib/ap/gen/abs.c/
#include <stdlib.h> int abs(int a) { if(a < 0) return -a; return a; } long labs(long a) { if(a < 0) return -a; return a; }