NAME

       halstreamer - stream file data into HAL in real time

SYNOPSIS

       halstreamer [options]

DESCRIPTION

       streamer(9) and halstreamer are used together to stream data from a file into the HAL in
       real time. streamer is a realtime HAL component that exports HAL pins and creates a FIFO
       in shared memory. hal_streamer is a user space program that copies data from stdin into
       the FIFO, so that streamer can write it to the HAL pins.

OPTIONS

       -c CHAN
           Instructs halstreamer to write to FIFO CHAN. FIFOs are numbered from zero, and the
           default value is zero, so this option is not needed unless multiple FIFOs have been
           created.

       FILENAME
           Instructs halsampler to read from FILENAME instead of from stdin.

USAGE

       A FIFO must first be created by loading streamer(9) with halcmd loadrt or a loadrt command
       in a .hal file. Then halstreamer can be invoked to begin writing data into the FIFO.

       Data is read from stdin, and is almost always either redirected from a file or piped from
       some other program, since keyboard input would be unable to keep up with even slow
       streaming rates.

       Each line of input must match the pins that are attached to the FIFO, for example, if the
       streamer config string was "ffbs" then each line of input must consist of two floats, a
       bit, and a signed integer, in that order and separated by whitespace. Floats must be
       formatted as required by strtod(3), signed and unsigned integers must be formatted as
       required by strtol(3) and strtoul(3), and bits must be either 0 or 1.

       Input lines that begin with # will be treated as comments and silently skipped.

       halstreamer transfers data to the FIFO as fast as possible until the FIFO is full, then it
       retries at regular intervals, until it is either killed or reads EOF from stdin. Data can
       be redirected from a file or piped from some other program.

       The FIFO size should be chosen to ride through any momentary disruptions in the flow of
       data, such as disk seeks. If the FIFO is big enough, halstreamer can be restarted with the
       same or a new file before the FIFO empties, resulting in a continuous stream of data.

       The data format for halstreamer input is the same as for halsampler(1) output, so
       waveforms captured with halsampler can be replayed using halstreamer.

EXIT STATUS

       If a problem is encountered during initialization, halstreamer prints a message to stderr
       and returns failure.

       If a badly formatted line is encountered while writing to the FIFO, it prints a message to
       stderr, skips the line, and continues (this behavior may be revised in the future).

       Upon reading EOF from the input, it returns success. If it is terminated before the input
       ends, it returns failure.

SEE ALSO

       streamer(9) sampler(9) halsampler(1)

AUTHOR

       Original version by John Kasunich, as part of the LinuxCNC project. Improvements by
       several other members of the LinuxCNC development team.

REPORTING BUGS

       Report bugs to jmkasunich AT users DOT sourceforge DOT net

COPYRIGHT

       Copyright © 2006 John Kasunich. This is free software; see the source for copying
       conditions. There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR
       PURPOSE.