ref: 68d9155e1fff6c4c2d69c96f3fd4e7dc66cdeebd 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; }