GNU cflow analyzes a collection of C source files and prints a graph,
charting control flow within the program.

GNU cflow is able to produce both direct and inverted flowgraphs for
C sources. Optionally a cross-reference listing can be generated. 
Two output formats are implemented: POSIX and GNU (extended).

Input files can optionally be preprocessed before analyzing.

The package also provides Emacs major mode for examining the produced
flowcharts in Emacs.