mdns: fix build on big-endian ports - #409
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nxd_mdns.c uses NX_CHANGE_USHORT_ENDIAN() as an expression:
*(USHORT *)(packet_ptr -> nx_packet_prepend_ptr + NX_MDNS_FLAGS_OFFSET)
|= NX_CHANGE_USHORT_ENDIAN(tc_bit);
Big-endian ports define that macro as empty, so it expands to
"*(USHORT *)(...) |= ;" and addons/mdns fails to compile on every
big-endian target.
It goes unnoticed on little-endian because those ports define the macro as
an assignment -- a = (((a >> 8) | (a << 8)) & 0xFFFF) -- which has a value
and so parses in expression position. Every other call site in the
repository uses the macro as a statement, which is what an
unconditionally-empty definition requires; see for example
test/regression/ptp_test/netx_ptp_utility.c. This is the only expression
use.
Swap in place, then OR, which keeps the macro used as a statement.
Verified against both upstream definitions: with the big-endian (empty)
definition the original fails to compile and this compiles; with the
little-endian definition both produce the same flags word, 0x0002.
Found while building addons/mdns for m68k AmigaOS.
Signed-off-by: Tinic Uro <tinicuro@gmail.com>
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nxd_mdns.c uses NX_CHANGE_USHORT_ENDIAN() as an expression:
Big-endian ports define that macro as empty, so it expands to "*(USHORT *)(...) |= ;" and addons/mdns fails to compile on every big-endian target.
It goes unnoticed on little-endian because those ports define the macro as an assignment -- a = (((a >> 8) | (a << 8)) & 0xFFFF) -- which has a value and so parses in expression position. Every other call site in the repository uses the macro as a statement, which is what an unconditionally-empty definition requires; see for example test/regression/ptp_test/netx_ptp_utility.c. This is the only expression use.
Swap in place, then OR, which keeps the macro used as a statement.
Verified against both upstream definitions: with the big-endian (empty) definition the original fails to compile and this compiles; with the little-endian definition both produce the same flags word, 0x0002.
Found while building addons/mdns for m68k AmigaOS.