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MdePkg/BaseLib: Add bit field population calculating methods

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Hopefully this should tidy the conversion warnings.

----

Add 32-bit and 64-bit functions that count number of set bits in a bitfield
using a divide-and-count method.

Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Tomas Pilar <tpilar@solarflare.com>
Cc: Liming Gao <liming.gao@intel.com>
Cc: Michael D Kinney <michael.d.kinney@intel.com>
Reviewed-by: Liming Gao <liming.gao@intel.com>
Reviewed-by: Michael Kinney <michael.d.kinney@intel.com>
This commit is contained in:
Tomas Pilar (tpilar) 2018-07-06 21:40:43 +08:00 committed by Liming Gao
parent 18ef4e713f
commit d7634dc0c5
2 changed files with 142 additions and 0 deletions
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56
MdePkg/Include/Library/BaseLib.h
View File

@ -4609,6 +4609,62 @@ BitFieldAndThenOr64 (
IN UINT64 OrData IN UINT64 OrData
); );
/**
Reads a bit field from a 32-bit value, counts and returns
the number of set bits.
Counts the number of set bits in the bit field specified by
StartBit and EndBit in Operand. The count is returned.
If StartBit is greater than 31, then ASSERT().
If EndBit is greater than 31, then ASSERT().
If EndBit is less than StartBit, then ASSERT().
@param Operand Operand on which to perform the bitfield operation.
@param StartBit The ordinal of the least significant bit in the bit field.
Range 0..31.
@param EndBit The ordinal of the most significant bit in the bit field.
Range 0..31.
@return The number of bits set between StartBit and EndBit.
**/
UINT8
EFIAPI
BitFieldCountOnes32 (
IN UINT32 Operand,
IN UINTN StartBit,
IN UINTN EndBit
);
/**
Reads a bit field from a 64-bit value, counts and returns
the number of set bits.
Counts the number of set bits in the bit field specified by
StartBit and EndBit in Operand. The count is returned.
If StartBit is greater than 63, then ASSERT().
If EndBit is greater than 63, then ASSERT().
If EndBit is less than StartBit, then ASSERT().
@param Operand Operand on which to perform the bitfield operation.
@param StartBit The ordinal of the least significant bit in the bit field.
Range 0..63.
@param EndBit The ordinal of the most significant bit in the bit field.
Range 0..63.
@return The number of bits set between StartBit and EndBit.
**/
UINT8
EFIAPI
BitFieldCountOnes64 (
IN UINT64 Operand,
IN UINTN StartBit,
IN UINTN EndBit
);
// //
// Base Library Checksum Functions // Base Library Checksum Functions
// //

86
MdePkg/Library/BaseLib/BitField.c
View File

@ -920,3 +920,89 @@ BitFieldAndThenOr64 (
OrData OrData
); );
} }
/**
Reads a bit field from a 32-bit value, counts and returns
the number of set bits.
Counts the number of set bits in the bit field specified by
StartBit and EndBit in Operand. The count is returned.
If StartBit is greater than 31, then ASSERT().
If EndBit is greater than 31, then ASSERT().
If EndBit is less than StartBit, then ASSERT().
@param Operand Operand on which to perform the bitfield operation.
@param StartBit The ordinal of the least significant bit in the bit field.
Range 0..31.
@param EndBit The ordinal of the most significant bit in the bit field.
Range 0..31.
@return The number of bits set between StartBit and EndBit.
**/
UINT8
EFIAPI
BitFieldCountOnes32 (
IN UINT32 Operand,
IN UINTN StartBit,
IN UINTN EndBit
)
{
UINT32 Count;
ASSERT (EndBit < 32);
ASSERT (StartBit <= EndBit);
Count = BitFieldRead32 (Operand, StartBit, EndBit);
Count -= ((Count >> 1) & 0x55555555);
Count = (Count & 0x33333333) + ((Count >> 2) & 0x33333333);
Count += Count >> 4;
Count &= 0x0F0F0F0F;
Count += Count >> 8;
Count += Count >> 16;
return (UINT8) Count & 0x3F;
}
/**
Reads a bit field from a 64-bit value, counts and returns
the number of set bits.
Counts the number of set bits in the bit field specified by
StartBit and EndBit in Operand. The count is returned.
If StartBit is greater than 63, then ASSERT().
If EndBit is greater than 63, then ASSERT().
If EndBit is less than StartBit, then ASSERT().
@param Operand Operand on which to perform the bitfield operation.
@param StartBit The ordinal of the least significant bit in the bit field.
Range 0..63.
@param EndBit The ordinal of the most significant bit in the bit field.
Range 0..63.
@return The number of bits set between StartBit and EndBit.
**/
UINT8
EFIAPI
BitFieldCountOnes64 (
IN UINT64 Operand,
IN UINTN StartBit,
IN UINTN EndBit
)
{
UINT64 BitField;
UINT8 Count;
ASSERT (EndBit < 64);
ASSERT (StartBit <= EndBit);
BitField = BitFieldRead64 (Operand, StartBit, EndBit);
Count = BitFieldCountOnes32 ((UINT32) BitField, 0, 31);
Count += BitFieldCountOnes32 ((UINT32) RShiftU64(BitField, 32), 0, 31);
return Count;
}