When using SCPI over serial (over USB), we want the header without waiting
for the terminating newline, as otherwise the transfer may time out.
sr_scpi_get_data() will block until the message is complete.
g_get_monotonic_time() returns current time in microseconds, use the same
granularity for storing the read timeout.
There is also no need to check the timeout if data has just been read.
When the channel state is retrieved, query the pre-set byteorder for
SCPI data blocks as well. When samples get retrieved during capture,
support float representations in either big or little endian format.
This commit unbreaks devices which operate in BE format by default
(tested with HMO2524). It keeps working with LE format as before. For
devices which don't support the byteorder query or return unknown
responses, LE format is assumed for backwards compatibility. The
device's byteorder is only queried and never set. This makes the
commit least intrusive.
Binary block data is specified in IEEE 488.2. First character is '#',
followed by a single ascii digit denoting the the number of digits needed
for the length specification. Length is given in bytes.
This allows drivers to replace retrieval of comma separated ASCII values
with binary formats. See bug #791.
Firmware versions starting with 00.02.04 apparently cause the in and out
bulk endpoints to end up in a HALT state. This is likely related to the
larger transfer size quirk implemented in the Linux kernel for the Rigol
DS1000: this USBTMC implementation does not have that workaround.
Instead, if the firmware version is >= 00.02.04, both endpoints have the HALT
condition cleared on device close.
This fixes bug #354.
Sven Schnelle
Stefan Brüns
Gerhard Sittig
Bert Vermeulen