C02/vcs/include/vcslib.txt

vcslib - Atari 2600 Library Functions for C02

This library contains commonly used functions for the Atari VCS.

  res = adcbcd(num, &var);    Adds value num plus carry to variable var 
                              using BCD arithmetic.
                              
                              Used to update multi-byte BCD numbers, such 
                              as scores with more than two digits.
                              
                              Returns the updated contents of var. Can
                              be called as a void function if the result
                              is not needed.

  res = addbcd(num, &var);    Adds value num to variable var using BCD 
                              arithmetic.
                              
                              Used to update BCD numbers, such as two
                              digit scores.
                              
                              Returns the updated contents of var. Can
                              be called as a void function if the result
                              is not needed.

  posobj(hrz, obj);           Sets horizontal position of object obj to
                              hrz.
                              
                              Argument obj may be any of the following:
                                0 = Player 0
                                1 = Player 1
                                2 = Missile 0
                                3 = Missile 1
                                4 = Ball