bitstring(3): Add bitstring traversal macros.

[wulf]

Summary

The macro bit_foreach() traverses all set bits in the bitstring in the
forward direction, assigning each location in turn to variable.

The macro bit_foreach_at() traverses all set bits in the bitstring in
the forward direction at or after the zero-based bit index, assigning
each location in turn to variable.

I am going to use them in future evdev and hms(4) work.

The bit_foreach_unset() and bit_foreach_unset_at() macros which
traverses unset bits are implemented for completeness.

[dougm]

Seems harmless.

sys/sys/bitstring.h

430

Nitpick: "in a bitstr" is present in line 422, but absent here. A comma is present here, but absent there.

[asomers]

You should also add new test cases to tests/sys/sys/bitstring_test.c .

[wulf]

1. Add test cases.
2. Make comments uniform.

[wulf]

sys/sys/bitstring.h

430

It was caused by "81-char line lenght" problem. Fixed.