Ticket #115 (defect)
Opened 2 years ago
Last modified 2 years ago
usrp read fails on Windows when nbytes > block_size
Status: closed (fixed)
| Reported by: | dward | Assigned to: | eb |
|---|---|---|---|
| Priority: | normal | Milestone: | release-3.0.3 |
| Component: | usrp | Version: | 3.0svn |
| Keywords: | windows cygwin mingw | Cc: | don2387ward@sprynet.com |
usrp_spectrum_sense.py with default options fails on Windows with either Cygwin or MSYS/MinGW (Python exits with no messages). I have traced the execution to fusb_ephandle_win32::read() where it reads d_block_size (4096 in this case) bytes then copies nbytes (bytes requested in call---16384 in this case) into the return buffer and sets
d_input_leftover = d_block_size - bytes_to_read;
In the next call, if (d_input_leftover != 0) it then copies more already-read bytes. But when bytes_to_read (==nbytes) is greater than d_block_size, garbage is copied on the first read, d_input_leftover is set to a negative value, and the program exits (don't know why) before returning from the second read.
I would be happy to work on fixing this, but I would need to know whether fusb_ephandle_win32::read() is allowed to return fewer bytes than requested or if must (or should, for efficiency) return the requested count.
Attachments
Change History
12/15/06 18:39:26: Modified by eb
- owner changed from matt to eb.
- status changed from new to assigned.
12/18/06 08:44:54: Modified by dward
- attachment fusb_win32.patch added.
patch fusb_win32.cc to fix ticket 115
12/18/06 08:54:18: Modified by dward
With the attached patch, enough blocks are read to return the requested number of bytes. The patch also fixes a similar problem with writing data. While this patch allows small packets to be used, I find that they require much more cpu time (on Windows) than large packets, and using enough small packets to prevent overruns can cause long delays (many seconds; for system cleanup?) after the program exits.
The patch has been tested on Cygwin and MinGW/MSYS.
12/19/06 15:55:17: Modified by eb
- status changed from assigned to closed.
- resolution set to fixed.
Patch applied in r4153.
02/07/07 13:14:54: Modified by jcorgan
- milestone changed from to-be-decided to release-3.0.3.
Hi Don, It is OK for read to return fewer bytes than requested. Definitely better than copying bogus data!
It will probably trigger this message in usrp1_source_base.cc
This message should probably be disabled.
Thanks for working on this. Please generate a patch. Eric