ref: 98dba9a4a311dd7b7435a5a5d66619f2a2b4b6cf 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; }