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[Bug 1001914] New: cyg_io_select behaves as "device ready" when the device driver actually doesn't support select?
- From: bugzilla-daemon at bugs dot ecos dot sourceware dot org
- To: ecos-bugs at ecos dot sourceware dot org
- Date: Sun, 10 Nov 2013 23:45:41 +0000
- Subject: [Bug 1001914] New: cyg_io_select behaves as "device ready" when the device driver actually doesn't support select?
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http://bugs.ecos.sourceware.org/show_bug.cgi?id=1001914
Bug ID: 1001914
Summary: cyg_io_select behaves as "device ready" when the
device driver actually doesn't support select?
Product: eCos
Version: 3.0
Target: All
Architecture/Host Other
OS:
Status: UNCONFIRMED
Severity: normal
Priority: low
Component: Other
Assignee: unassigned@bugs.ecos.sourceware.org
Reporter: vlad_a_pudovkin@hotmail.com
CC: ecos-bugs@ecos.sourceware.org
The cyg_io_select seems to be not covered by the official eCos reference guide;
the only sort of "spec" I found for it was this snippet from the header
packages/io/common/<version>/include/io.h:
// Test a device for readiness
cyg_bool cyg_io_select(cyg_io_handle_t handle,
cyg_uint32 which,
CYG_ADDRWORD info);
The code of this function (file packages/io/common/<version>/src/iosys.c) seems
to try to encode one "special value" into type cyg_bool:
cyg_bool
cyg_io_select(cyg_io_handle_t handle, cyg_uint32 which, CYG_ADDRWORD info)
{
cyg_devtab_entry_t *t = (cyg_devtab_entry_t *)handle;
// Validate request
if (!t->handlers->select) {
return -EDEVNOSUPP;
}
return t->handlers->select( handle, which, info );
}
There are two issues with this "special value":
1) This return statement issues a compiler warning like this:
implicit conversion from 'int' to 'cyg_bool' (aka 'unsigned char') changes
value from -202 to 54
2) It is somewhat confusing to have one peculiar "true" value to actually
indicate an error while other "true" values mean that the device is ready. The
whole ecos code does not seem to contain examples of using the return value of
this function, which otherwise could help figuring out the "recommended" way of
using that return value.
This lack of cyg_io_select usage examples in the whole ecos code makes me
wonder whether this is a widely used function or rather a work in progress?
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