audk/MdePkg/Library/BaseLib
Ard Biesheuvel b331b99fae MdePkg/BaseLib: do not rely on undefined behavior in arithmetic shift
The runtime test whether the compiler supports arithmetic shift of
negative signed numbers currently relies on undefined behavior in C,
which means that all bets are off regarding whether the condition
that follows passes or fails, regardless of whether the compiler in
fact supports arithmetic shift or not.

Relevant quote from ISO C99 (6.5.7/4)

  The result of E1 << E2 is E1 left-shifted E2 bit positions; vacated bits
  are filled with zeros. If E1 has an unsigned type, the value of the result
  is E1 × 2^E2, reduced modulo one more than the maximum value representable
  in the result type. If E1 has a signed type and nonnegative value, and
  E1 × 2^E2 is representable in the result type, then that is the resulting
  value; otherwise, the behavior is undefined.

For historic purposes, let's keep the test in place (although it is doubtful
we actually need it) but rewrite it in a way that prevents compilers from
this century from doing whacky things with it.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Reviewed-by: Liming Gao <liming.gao@intel.com>

git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@19580 6f19259b-4bc3-4df7-8a09-765794883524
2015-12-31 10:47:22 +00:00
..
AArch64 MdePkg/AArch64: use GCC_ASM_EXPORT to export functions 2015-07-09 10:43:27 +00:00
Arm MdePkg: fix ARM version of InternalMathSwapBytes64 () 2015-03-27 17:27:14 +00:00
Ebc
Ia32 MdePkg: Add CPU RdRand access APIs for random number generation 2015-09-21 05:53:52 +00:00
Ipf Current IPF version SwitchStack implementation uses loadrs instruction to restore dirty partition of register stack from the backing store, but there is no guarantee to make the backing store valid before. So add flushrs before loadrs to make sure backing store valid. 2012-04-11 01:56:48 +00:00
X64 MdePkg: Add CPU RdRand access APIs for random number generation 2015-09-21 05:53:52 +00:00
ARShiftU64.c Minor grammatical work--mostly adding periods. Items with ONLY period added did not have the heading date changed, but Items with content changes had heading copyright dates updated. Sending separately a list of files missing Doxygen @param and @return information. (PENDING) 2010-06-24 00:20:35 +00:00
BaseLib.inf MdePkg: BaseLib don't require NASM with Xcode 2015-11-11 02:28:51 +00:00
BaseLib.uni MdePkg: Convert all .uni files to utf-8 2015-12-15 04:53:50 +00:00
BaseLibInternals.h Fix minor typos in BaseLib LinkedList comments 2013-03-13 06:44:10 +00:00
BitField.c Correctly character in comments of BaseLib BitField. 2013-07-22 06:41:52 +00:00
CheckSum.c Minor grammatical work--mostly adding periods. Items with ONLY period added did not have the heading date changed, but Items with content changes had heading copyright dates updated. Sending separately a list of files missing Doxygen @param and @return information. (PENDING) 2010-06-24 00:20:35 +00:00
ChkStkGcc.c Minor grammatical work--mostly adding periods. Items with ONLY period added did not have the heading date changed, but Items with content changes had heading copyright dates updated. Sending separately a list of files missing Doxygen @param and @return information. (PENDING) 2010-06-24 00:20:35 +00:00
Cpu.c Minor grammatical work--mostly adding periods. Items with ONLY period added did not have the heading date changed, but Items with content changes had heading copyright dates updated. Sending separately a list of files missing Doxygen @param and @return information. (PENDING) 2010-06-24 00:20:35 +00:00
CpuDeadLoop.c Minor grammatical work--mostly adding periods. Items with ONLY period added did not have the heading date changed, but Items with content changes had heading copyright dates updated. Sending separately a list of files missing Doxygen @param and @return information. (PENDING) 2010-06-24 00:20:35 +00:00
DivS64x64Remainder.c Minor grammatical work--mostly adding periods. Items with ONLY period added did not have the heading date changed, but Items with content changes had heading copyright dates updated. Sending separately a list of files missing Doxygen @param and @return information. (PENDING) 2010-06-24 00:20:35 +00:00
DivU64x32.c Minor grammatical work--mostly adding periods. Items with ONLY period added did not have the heading date changed, but Items with content changes had heading copyright dates updated. Sending separately a list of files missing Doxygen @param and @return information. (PENDING) 2010-06-24 00:20:35 +00:00
DivU64x32Remainder.c Minor grammatical work--mostly adding periods. Items with ONLY period added did not have the heading date changed, but Items with content changes had heading copyright dates updated. Sending separately a list of files missing Doxygen @param and @return information. (PENDING) 2010-06-24 00:20:35 +00:00
DivU64x64Remainder.c Minor grammatical work--mostly adding periods. Items with ONLY period added did not have the heading date changed, but Items with content changes had heading copyright dates updated. Sending separately a list of files missing Doxygen @param and @return information. (PENDING) 2010-06-24 00:20:35 +00:00
FilePaths.c MdeModulePkg, MdePkg, NetworkPkg, OvmfPkg, PerformancePkg, ShellPkg: Library Migration. 2015-01-13 01:04:07 +00:00
GetPowerOfTwo32.c Minor grammatical work--mostly adding periods. Items with ONLY period added did not have the heading date changed, but Items with content changes had heading copyright dates updated. Sending separately a list of files missing Doxygen @param and @return information. (PENDING) 2010-06-24 00:20:35 +00:00
GetPowerOfTwo64.c Fixed K9 scan issues. 2010-08-09 06:28:01 +00:00
HighBitSet32.c Minor grammatical work--mostly adding periods. Items with ONLY period added did not have the heading date changed, but Items with content changes had heading copyright dates updated. Sending separately a list of files missing Doxygen @param and @return information. (PENDING) 2010-06-24 00:20:35 +00:00
HighBitSet64.c Minor grammatical work--mostly adding periods. Items with ONLY period added did not have the heading date changed, but Items with content changes had heading copyright dates updated. Sending separately a list of files missing Doxygen @param and @return information. (PENDING) 2010-06-24 00:20:35 +00:00
LRotU32.c Minor grammatical work--mostly adding periods. Items with ONLY period added did not have the heading date changed, but Items with content changes had heading copyright dates updated. Sending separately a list of files missing Doxygen @param and @return information. (PENDING) 2010-06-24 00:20:35 +00:00
LRotU64.c Minor grammatical work--mostly adding periods. Items with ONLY period added did not have the heading date changed, but Items with content changes had heading copyright dates updated. Sending separately a list of files missing Doxygen @param and @return information. (PENDING) 2010-06-24 00:20:35 +00:00
LShiftU64.c Minor grammatical work--mostly adding periods. Items with ONLY period added did not have the heading date changed, but Items with content changes had heading copyright dates updated. Sending separately a list of files missing Doxygen @param and @return information. (PENDING) 2010-06-24 00:20:35 +00:00
LinkedList.c Match the comments with the implementation for Baselib::GetFirstNode. 2013-08-08 03:35:09 +00:00
LongJump.c Minor grammatical work--mostly adding periods. Items with ONLY period added did not have the heading date changed, but Items with content changes had heading copyright dates updated. Sending separately a list of files missing Doxygen @param and @return information. (PENDING) 2010-06-24 00:20:35 +00:00
LowBitSet32.c Minor grammatical work--mostly adding periods. Items with ONLY period added did not have the heading date changed, but Items with content changes had heading copyright dates updated. Sending separately a list of files missing Doxygen @param and @return information. (PENDING) 2010-06-24 00:20:35 +00:00
LowBitSet64.c Minor grammatical work--mostly adding periods. Items with ONLY period added did not have the heading date changed, but Items with content changes had heading copyright dates updated. Sending separately a list of files missing Doxygen @param and @return information. (PENDING) 2010-06-24 00:20:35 +00:00
Math64.c MdePkg/BaseLib: do not rely on undefined behavior in arithmetic shift 2015-12-31 10:47:22 +00:00
ModU64x32.c Minor grammatical work--mostly adding periods. Items with ONLY period added did not have the heading date changed, but Items with content changes had heading copyright dates updated. Sending separately a list of files missing Doxygen @param and @return information. (PENDING) 2010-06-24 00:20:35 +00:00
MultS64x64.c Fixed K9 scan issues. 2010-08-09 06:28:01 +00:00
MultU64x32.c Minor grammatical work--mostly adding periods. Items with ONLY period added did not have the heading date changed, but Items with content changes had heading copyright dates updated. Sending separately a list of files missing Doxygen @param and @return information. (PENDING) 2010-06-24 00:20:35 +00:00
MultU64x64.c Minor grammatical work--mostly adding periods. Items with ONLY period added did not have the heading date changed, but Items with content changes had heading copyright dates updated. Sending separately a list of files missing Doxygen @param and @return information. (PENDING) 2010-06-24 00:20:35 +00:00
RRotU32.c Minor grammatical work--mostly adding periods. Items with ONLY period added did not have the heading date changed, but Items with content changes had heading copyright dates updated. Sending separately a list of files missing Doxygen @param and @return information. (PENDING) 2010-06-24 00:20:35 +00:00
RRotU64.c Minor grammatical work--mostly adding periods. Items with ONLY period added did not have the heading date changed, but Items with content changes had heading copyright dates updated. Sending separately a list of files missing Doxygen @param and @return information. (PENDING) 2010-06-24 00:20:35 +00:00
RShiftU64.c Minor grammatical work--mostly adding periods. Items with ONLY period added did not have the heading date changed, but Items with content changes had heading copyright dates updated. Sending separately a list of files missing Doxygen @param and @return information. (PENDING) 2010-06-24 00:20:35 +00:00
SafeString.c MdePkg: ensure SafeString length functions don't access beyond MaxSize 2015-07-13 11:35:28 +00:00
SetJump.c Minor grammatical work--mostly adding periods. Items with ONLY period added did not have the heading date changed, but Items with content changes had heading copyright dates updated. Sending separately a list of files missing Doxygen @param and @return information. (PENDING) 2010-06-24 00:20:35 +00:00
String.c MdePkg: Add deprecate flag for the functions which has a replace function in safe c library. 2014-12-15 10:05:42 +00:00
SwapBytes16.c Minor grammatical work--mostly adding periods. Items with ONLY period added did not have the heading date changed, but Items with content changes had heading copyright dates updated. Sending separately a list of files missing Doxygen @param and @return information. (PENDING) 2010-06-24 00:20:35 +00:00
SwapBytes32.c Minor grammatical work--mostly adding periods. Items with ONLY period added did not have the heading date changed, but Items with content changes had heading copyright dates updated. Sending separately a list of files missing Doxygen @param and @return information. (PENDING) 2010-06-24 00:20:35 +00:00
SwapBytes64.c Minor grammatical work--mostly adding periods. Items with ONLY period added did not have the heading date changed, but Items with content changes had heading copyright dates updated. Sending separately a list of files missing Doxygen @param and @return information. (PENDING) 2010-06-24 00:20:35 +00:00
SwitchStack.c Minor grammatical work--mostly adding periods. Items with ONLY period added did not have the heading date changed, but Items with content changes had heading copyright dates updated. Sending separately a list of files missing Doxygen @param and @return information. (PENDING) 2010-06-24 00:20:35 +00:00
Unaligned.c Minor grammatical work--mostly adding periods. Items with ONLY period added did not have the heading date changed, but Items with content changes had heading copyright dates updated. Sending separately a list of files missing Doxygen @param and @return information. (PENDING) 2010-06-24 00:20:35 +00:00
X86DisablePaging32.c Minor grammatical work--mostly adding periods. Items with ONLY period added did not have the heading date changed, but Items with content changes had heading copyright dates updated. Sending separately a list of files missing Doxygen @param and @return information. (PENDING) 2010-06-24 00:20:35 +00:00
X86DisablePaging64.c Minor grammatical work--mostly adding periods. Items with ONLY period added did not have the heading date changed, but Items with content changes had heading copyright dates updated. Sending separately a list of files missing Doxygen @param and @return information. (PENDING) 2010-06-24 00:20:35 +00:00
X86EnablePaging32.c Minor grammatical work--mostly adding periods. Items with ONLY period added did not have the heading date changed, but Items with content changes had heading copyright dates updated. Sending separately a list of files missing Doxygen @param and @return information. (PENDING) 2010-06-24 00:20:35 +00:00
X86EnablePaging64.c Minor grammatical work--mostly adding periods. Items with ONLY period added did not have the heading date changed, but Items with content changes had heading copyright dates updated. Sending separately a list of files missing Doxygen @param and @return information. (PENDING) 2010-06-24 00:20:35 +00:00
X86FxRestore.c Fix memory out of band access in AsmFxSave() and AsmFxRestore(). 2012-10-30 08:35:08 +00:00
X86FxSave.c Fix memory out of band access in AsmFxSave() and AsmFxRestore(). 2012-10-30 08:35:08 +00:00
X86GetInterruptState.c Minor grammatical work--mostly adding periods. Items with ONLY period added did not have the heading date changed, but Items with content changes had heading copyright dates updated. Sending separately a list of files missing Doxygen @param and @return information. (PENDING) 2010-06-24 00:20:35 +00:00
X86MemoryFence.c Minor grammatical work--mostly adding periods. Items with ONLY period added did not have the heading date changed, but Items with content changes had heading copyright dates updated. Sending separately a list of files missing Doxygen @param and @return information. (PENDING) 2010-06-24 00:20:35 +00:00
X86Msr.c Add ASSERT() for BitField operations to make sure the input value is valid. 2012-12-25 02:25:50 +00:00
X86ReadGdtr.c Minor grammatical work--mostly adding periods. Items with ONLY period added did not have the heading date changed, but Items with content changes had heading copyright dates updated. Sending separately a list of files missing Doxygen @param and @return information. (PENDING) 2010-06-25 21:56:02 +00:00
X86ReadIdtr.c Minor grammatical work--mostly adding periods. Items with ONLY period added did not have the heading date changed, but Items with content changes had heading copyright dates updated. Sending separately a list of files missing Doxygen @param and @return information. (PENDING) 2010-06-25 21:56:02 +00:00
X86Thunk.c Update the modifier of ThunkContext parameter for AsmPrepareThunk16() in BaseLib from OUT to IN OUT. 2012-02-27 07:46:04 +00:00
X86WriteGdtr.c Minor grammatical work--mostly adding periods. Items with ONLY period added did not have the heading date changed, but Items with content changes had heading copyright dates updated. Sending separately a list of files missing Doxygen @param and @return information. (PENDING) 2010-06-25 21:56:02 +00:00
X86WriteIdtr.c Minor grammatical work--mostly adding periods. Items with ONLY period added did not have the heading date changed, but Items with content changes had heading copyright dates updated. Sending separately a list of files missing Doxygen @param and @return information. (PENDING) 2010-06-25 21:56:02 +00:00