Beginning x64 Assembly Programming: From Novice to AVX Professional

© Jo Van Hoey 2019

J. Van HoeyBeginning x64 Assembly Programminghttps://doi.org/10.1007/978-1-4842-5076-1_14

14. External Functions

Jo Van Hoey¹ 

(1)

Hamme, Belgium

 

We already know how to create and use functions in our source code. But the functions do not have to reside in the same file as our main program. We can write and assemble these functions in a separate file and link them in when building the program. The function printf, which we already used several times, is an example of an external function. In the source file where you plan to use the external function, you declare it with the keyword extern , and the assembler knows it does not have to look for the source of the function. The assembler will assume that the function is already assembled ...