Interfacing an External C Program with a Port
We’ll start with some simple C code. example1.c contains two functions. The first function computes the sum of two integers, and the second computes twice its argument.
| ports/example1.c | |
| | int sum(int x, int y){ |
| | return x+y; |
| | } |
| | |
| | int twice(int x){ |
| | return 2*x; |
| | } |
Our final goal is to call these routines from Erlang. We’d like to be able to call them as follows:
| | X1 = example1:sum(12,23), |
| | Y1 = example1:twice(10), |
As far as the user is concerned, example1 is an Erlang
module, and therefore all details of the interface to the C program
should be hidden inside the module example1.
To implement this, we need to turn function calls
such as sum(12,23)
and twice(10) into sequences of bytes ...
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