ref: 7cb2db12f85c6dbc6a7f36bbfb655e6b7c19a28c 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; }