Calispel is licensed under permissive, BSD-like terms, copied from the
ISC license:

    Copyright (c) 2009, Jean-Paul Guy Larocque
    
    Permission to use, copy, modify, and/or distribute this software
    for any purpose with or without fee is hereby granted, provided
    that the above copyright notice and this permission notice appear
    in all copies.
    
    THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL
    WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED
    WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE
    AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR
    CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
    LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT,
    NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
    CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.

This software was directly derived from "csp.tgz"
<http://www.staff.ncl.ac.uk/roger.peppe/csp.tgz>, dated 2006-07-03,
and published by Roger Peppe.  No copyright notice giving attribution
to Roger Peppe or any specific licensing terms seem to have been
included in that version.

That software was derived from "channel.c" of Plan 9 libthread:

    Copyright (c) 2005 Russ Cox,
                       Massachusetts Institute of Technology

    Permission is hereby granted, free of charge, to any person
    obtaining a copy of this software and associated documentation
    files (the "Software"), to deal in the Software without
    restriction, including without limitation the rights to use, copy,
    modify, merge, publish, distribute, sublicense, and/or sell copies
    of the Software, and to permit persons to whom the Software is
    furnished to do so, subject to the following conditions:
    
    The above copyright notice and this permission notice shall be
    included in all copies or substantial portions of the Software.
    
    THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
    EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
    MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
    NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
    HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
    WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
    OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
    DEALINGS IN THE SOFTWARE.

That software contains parts derived from an earlier library by Rob
Pike, Sape Mullender, and Russ Cox:

    Copyright (c) 2003 by Lucent Technologies.
    
    Permission to use, copy, modify, and distribute this software for
    any purpose without fee is hereby granted, provided that this
    entire notice is included in all copies of any software which is
    or includes a copy or modification of this software and in all
    copies of the supporting documentation for such software.
    
    THIS SOFTWARE IS BEING PROVIDED "AS IS", WITHOUT ANY EXPRESS OR
    IMPLIED WARRANTY.  IN PARTICULAR, NEITHER THE AUTHORS NOR LUCENT
    TECHNOLOGIES MAKE ANY REPRESENTATION OR WARRANTY OF ANY KIND
    CONCERNING THE MERCHANTABILITY OF THIS SOFTWARE OR ITS FITNESS FOR
    ANY PARTICULAR PURPOSE.