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 real-time HAL component that exports HAL pins and creates a FIFO in shared memory.
       hal_streamer is a non-realtime 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.

LinuxCNC                                           08/07/2025                                     HALSTREAMER(1)