From d7634dc0c5a83360b3b6c155df29c078ad9c77ce Mon Sep 17 00:00:00 2001
From: "Tomas Pilar (tpilar)"
Date: Fri, 6 Jul 2018 21:40:43 +0800
Subject: [PATCH 1/1] MdePkg/BaseLib: Add bit field population calculating
methods
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
Cc: Liming Gao
Cc: Michael D Kinney
Reviewed-by: Liming Gao
Reviewed-by: Michael Kinney
---
MdePkg/Include/Library/BaseLib.h | 56 ++++++++++++++++++++
MdePkg/Library/BaseLib/BitField.c | 86 +++++++++++++++++++++++++++++++
2 files changed, 142 insertions(+)
diff --git a/MdePkg/Include/Library/BaseLib.h b/MdePkg/Include/Library/BaseLib.h
index 1db3a0475d..123ae19dc2 100644
--- a/MdePkg/Include/Library/BaseLib.h
+++ b/MdePkg/Include/Library/BaseLib.h
@@ -4609,6 +4609,62 @@ BitFieldAndThenOr64 (
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
//
diff --git a/MdePkg/Library/BaseLib/BitField.c b/MdePkg/Library/BaseLib/BitField.c
index d2d3150f2a..645a662e81 100644
--- a/MdePkg/Library/BaseLib/BitField.c
+++ b/MdePkg/Library/BaseLib/BitField.c
@@ -920,3 +920,89 @@ BitFieldAndThenOr64 (
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;
+}
+
--
2.30.2