PcAtChipsetPkg/SerialIoLib: Remove negative value shift
authorMichael Kinney <michael.d.kinney@intel.com>
Wed, 3 May 2017 00:23:22 +0000 (17:23 -0700)
committerMichael Kinney <michael.d.kinney@intel.com>
Fri, 19 May 2017 19:12:06 +0000 (12:12 -0700)
commitbbd61de5dbc6ad146dc7250e9646cb662604b5f3
tree955575ad4dff51a768db1d018e7340c2e45e13ca
parentda0df6ca8f8f118866e53c7fb770598c199993a6
PcAtChipsetPkg/SerialIoLib: Remove negative value shift

https://bugzilla.tianocore.org/show_bug.cgi?id=553

Remove left shift of negative values that always evaluate
to 0 to address build errors from the llvm/clang compiler
used in the XCODE5 tool chain.

Clang rightfully complains about left-shifting ~DLAB. DLAB is #defined
as 0x01 (an "int"), hence ~DLAB has value (-2) on all edk2 platforms.
Left-shifting a negative int is undefined behavior.

Rather than replacing ~DLAB with ~(UINT32)DLAB, realize that the nonzero
bits of (~(UINT32)DLAB << 7) would all be truncated away in the final
conversion to UINT8 anyway. So just remove (~DLAB << 7).

Cc: Ruiyu Ni <ruiyu.ni@intel.com>
Cc: Andrew Fish <afish@apple.com>
Cc: Laszlo Ersek <lersek@redhat.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Michael D Kinney <michael.d.kinney@intel.com>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>
PcAtChipsetPkg/Library/SerialIoLib/SerialPortLib.c