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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>
This commit is contained in:
Michael Kinney 2017-05-02 17:23:22 -07:00
parent da0df6ca8f
commit bbd61de5db
1 changed files with 2 additions and 2 deletions
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4
PcAtChipsetPkg/Library/SerialIoLib/SerialPortLib.c
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@ -102,7 +102,7 @@ SerialPortInitialize (
// //
// Switch back to bank 0 // Switch back to bank 0
// //
OutputData = (UINT8) ((~DLAB << 7) | (gBreakSet << 6) | (gParity << 3) | (gStop << 2) | Data); OutputData = (UINT8) ( (gBreakSet << 6) | (gParity << 3) | (gStop << 2) | Data);
IoWrite8 (gUartBase + LCR_OFFSET, OutputData); IoWrite8 (gUartBase + LCR_OFFSET, OutputData);
return RETURN_SUCCESS; return RETURN_SUCCESS;
@ -481,7 +481,7 @@ SerialPortSetAttributes (
// //
// Switch back to bank 0 // Switch back to bank 0
// //
OutputData = (UINT8) ((~DLAB << 7) | (gBreakSet << 6) | (LcrParity << 3) | (LcrStop << 2) | LcrData); OutputData = (UINT8) ((gBreakSet << 6) | (LcrParity << 3) | (LcrStop << 2) | LcrData);
IoWrite8 (gUartBase + LCR_OFFSET, OutputData); IoWrite8 (gUartBase + LCR_OFFSET, OutputData);
return RETURN_SUCCESS; return RETURN_SUCCESS;