Introduce a helper function to determine the number of scans left in the async command. Signed-off-by: H Hartley Sweeten <hsweeten@xxxxxxxxxxxxxxxxxxx> Cc: Ian Abbott <abbotti@xxxxxxxxx> Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- drivers/staging/comedi/comedidev.h | 2 ++ drivers/staging/comedi/drivers.c | 39 ++++++++++++++++++++++++++++++++++++++ 2 files changed, 41 insertions(+) diff --git a/drivers/staging/comedi/comedidev.h b/drivers/staging/comedi/comedidev.h index bff5a58..e3ef5cc 100644 --- a/drivers/staging/comedi/comedidev.h +++ b/drivers/staging/comedi/comedidev.h @@ -516,6 +516,8 @@ int comedi_dio_insn_config(struct comedi_device *, struct comedi_subdevice *, unsigned int comedi_dio_update_state(struct comedi_subdevice *, unsigned int *data); unsigned int comedi_bytes_per_scan(struct comedi_subdevice *s); +unsigned int comedi_nscans_left(struct comedi_subdevice *s, + unsigned int nscans); void comedi_inc_scan_progress(struct comedi_subdevice *s, unsigned int num_bytes); diff --git a/drivers/staging/comedi/drivers.c b/drivers/staging/comedi/drivers.c index 02a01ba..00194a5 100644 --- a/drivers/staging/comedi/drivers.c +++ b/drivers/staging/comedi/drivers.c @@ -328,6 +328,45 @@ unsigned int comedi_bytes_per_scan(struct comedi_subdevice *s) EXPORT_SYMBOL_GPL(comedi_bytes_per_scan); /** + * comedi_nscans_left - return the number of scans left in the command + * @s: comedi_subdevice struct + * @nscans: the expected number of scans + * + * If nscans is 0, the number of scans available in the async buffer will be + * used. Otherwise the expected number of scans will be used. + * + * If the async command has a stop_src of TRIG_COUNT, the nscans will be + * checked against the number of scans left in the command. + * + * The return value will then be either the expected number of scans or the + * number of scans remaining in the command. + */ +unsigned int comedi_nscans_left(struct comedi_subdevice *s, + unsigned int nscans) +{ + struct comedi_async *async = s->async; + struct comedi_cmd *cmd = &async->cmd; + + if (nscans == 0) { + unsigned int nbytes = comedi_buf_read_n_available(s); + + nscans = nbytes / comedi_bytes_per_scan(s); + } + + if (cmd->stop_src == TRIG_COUNT) { + unsigned int scans_left = 0; + + if (async->scans_done < cmd->stop_arg) + scans_left = cmd->stop_arg - async->scans_done; + + if (nscans > scans_left) + nscans = scans_left; + } + return nscans; +} +EXPORT_SYMBOL_GPL(comedi_nscans_left); + +/** * comedi_inc_scan_progress - update scan progress in asynchronous command * @s: comedi_subdevice struct * @num_bytes: amount of data in bytes to increment scan progress -- 2.0.3 _______________________________________________ devel mailing list devel@xxxxxxxxxxxxxxxxxxxxxx http://driverdev.linuxdriverproject.org/mailman/listinfo/driverdev-devel