ref: 1c0e91bc1b5dc31f51a1eb5acf5f99378e2c14af 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; }