-@command{gcov} uses three files for doing profiling. The names of these
-files are derived from the original @emph{source} file by substituting
-the file suffix with either @file{.bb}, @file{.bbg}, or @file{.da}. All
-of these files are placed in the same directory as the source file, and
-contain data stored in a platform-independent method.
-
-The @file{.bb} and @file{.bbg} files are generated when the source file
-is compiled with the GCC @option{-ftest-coverage} option. The
-@file{.bb} file contains a list of source files (including headers),
-functions within those files, and line numbers corresponding to each
-basic block in the source file.
-
-The @file{.bb} file format consists of several lists of 4-byte integers
-which correspond to the line numbers of each basic block in the
-file. Each list is terminated by a line number of 0. A line number of @minus{}1
-is used to designate that the source file name (padded to a 4-byte
-boundary and followed by another @minus{}1) follows. In addition, a line number
-of @minus{}2 is used to designate that the name of a function (also padded to a
-4-byte boundary and followed by a @minus{}2) follows.
-
-The @file{.bbg} file is used to reconstruct the program flow graph for
-the source file. It contains a list of the program flow arcs (possible
-branches taken from one basic block to another) for each function which,
-in combination with the @file{.bb} file, enables gcov to reconstruct the
-program flow.
-
-In the @file{.bbg} file, the format is:
-@smallexample
- number of basic blocks for function #0 (4-byte number)
- total number of arcs for function #0 (4-byte number)
- count of arcs in basic block #0 (4-byte number)
- destination basic block of arc #0 (4-byte number)
- flag bits (4-byte number)
- destination basic block of arc #1 (4-byte number)
- flag bits (4-byte number)
- @dots{}
- destination basic block of arc #N (4-byte number)
- flag bits (4-byte number)
- count of arcs in basic block #1 (4-byte number)
- destination basic block of arc #0 (4-byte number)
- flag bits (4-byte number)
- @dots{}
-@end smallexample