From 0b6c0afeb7d5eb4a44897303a4e93d6c863c486d Mon Sep 17 00:00:00 2001
From: aroulin <andy.roulin@epfl.ch>
Date: Wed, 26 Aug 2015 09:11:07 +0200
Subject: [PATCH] Common: Import BitSet from Dolphin
---
src/common/CMakeLists.txt | 1 +
src/common/bit_set.h | 189 ++++++++++++++++++++++++++++++++++++++
2 files changed, 190 insertions(+)
create mode 100644 src/common/bit_set.h
diff --git a/src/common/CMakeLists.txt b/src/common/CMakeLists.txt
index 7f3712efab..2be6fe9961 100644
--- a/src/common/CMakeLists.txt
+++ b/src/common/CMakeLists.txt
@@ -24,6 +24,7 @@ set(SRCS
set(HEADERS
assert.h
bit_field.h
+ bit_set.h
break_points.h
chunk_file.h
code_block.h
diff --git a/src/common/bit_set.h b/src/common/bit_set.h
new file mode 100644
index 0000000000..85f91e7860
--- /dev/null
+++ b/src/common/bit_set.h
@@ -0,0 +1,189 @@
+// This file is under the public domain.
+
+#pragma once
+
+#include <cstddef>
+#ifdef _WIN32
+#include <intrin.h>
+#endif
+#include <initializer_list>
+#include <type_traits>
+#include "common/common_types.h"
+
+// namespace avoids conflict with OS X Carbon; don't use BitSet<T> directly
+namespace Common {
+
+// Helper functions:
+
+#ifdef _WIN32
+template <typename T>
+static inline int CountSetBits(T v)
+{
+ // from https://graphics.stanford.edu/~seander/bithacks.html
+ // GCC has this built in, but MSVC's intrinsic will only emit the actual
+ // POPCNT instruction, which we're not depending on
+ v = v - ((v >> 1) & (T)~(T)0/3);
+ v = (v & (T)~(T)0/15*3) + ((v >> 2) & (T)~(T)0/15*3);
+ v = (v + (v >> 4)) & (T)~(T)0/255*15;
+ return (T)(v * ((T)~(T)0/255)) >> (sizeof(T) - 1) * 8;
+}
+static inline int LeastSignificantSetBit(u8 val)
+{
+ unsigned long index;
+ _BitScanForward(&index, val);
+ return (int)index;
+}
+static inline int LeastSignificantSetBit(u16 val)
+{
+ unsigned long index;
+ _BitScanForward(&index, val);
+ return (int)index;
+}
+static inline int LeastSignificantSetBit(u32 val)
+{
+ unsigned long index;
+ _BitScanForward(&index, val);
+ return (int)index;
+}
+static inline int LeastSignificantSetBit(u64 val)
+{
+ unsigned long index;
+ _BitScanForward64(&index, val);
+ return (int)index;
+}
+#else
+static inline int CountSetBits(u8 val) { return __builtin_popcount(val); }
+static inline int CountSetBits(u16 val) { return __builtin_popcount(val); }
+static inline int CountSetBits(u32 val) { return __builtin_popcount(val); }
+static inline int CountSetBits(u64 val) { return __builtin_popcountll(val); }
+static inline int LeastSignificantSetBit(u8 val) { return __builtin_ctz(val); }
+static inline int LeastSignificantSetBit(u16 val) { return __builtin_ctz(val); }
+static inline int LeastSignificantSetBit(u32 val) { return __builtin_ctz(val); }
+static inline int LeastSignificantSetBit(u64 val) { return __builtin_ctzll(val); }
+#endif
+
+// Similar to std::bitset, this is a class which encapsulates a bitset, i.e.
+// using the set bits of an integer to represent a set of integers. Like that
+// class, it acts like an array of bools:
+// BitSet32 bs;
+// bs[1] = true;
+// but also like the underlying integer ([0] = least significant bit):
+// BitSet32 bs2 = ...;
+// bs = (bs ^ bs2) & BitSet32(0xffff);
+// The following additional functionality is provided:
+// - Construction using an initializer list.
+// BitSet bs { 1, 2, 4, 8 };
+// - Efficiently iterating through the set bits:
+// for (int i : bs)
+// [i is the *index* of a set bit]
+// (This uses the appropriate CPU instruction to find the next set bit in one
+// operation.)
+// - Counting set bits using .Count() - see comment on that method.
+
+// TODO: use constexpr when MSVC gets out of the Dark Ages
+
+template <typename IntTy>
+class BitSet
+{
+ static_assert(!std::is_signed<IntTy>::value, "BitSet should not be used with signed types");
+public:
+ // A reference to a particular bit, returned from operator[].
+ class Ref
+ {
+ public:
+ Ref(Ref&& other) : m_bs(other.m_bs), m_mask(other.m_mask) {}
+ Ref(BitSet* bs, IntTy mask) : m_bs(bs), m_mask(mask) {}
+ operator bool() const { return (m_bs->m_val & m_mask) != 0; }
+ bool operator=(bool set)
+ {
+ m_bs->m_val = (m_bs->m_val & ~m_mask) | (set ? m_mask : 0);
+ return set;
+ }
+ private:
+ BitSet* m_bs;
+ IntTy m_mask;
+ };
+
+ // A STL-like iterator is required to be able to use range-based for loops.
+ class Iterator
+ {
+ public:
+ Iterator(const Iterator& other) : m_val(other.m_val), m_bit(other.m_bit) {}
+ Iterator(IntTy val, int bit) : m_val(val), m_bit(bit) {}
+ Iterator& operator=(Iterator other) { new (this) Iterator(other); return *this; }
+ int operator*() { return m_bit; }
+ Iterator& operator++()
+ {
+ if (m_val == 0)
+ {
+ m_bit = -1;
+ }
+ else
+ {
+ int bit = LeastSignificantSetBit(m_val);
+ m_val &= ~(1 << bit);
+ m_bit = bit;
+ }
+ return *this;
+ }
+ Iterator operator++(int _)
+ {
+ Iterator other(*this);
+ ++*this;
+ return other;
+ }
+ bool operator==(Iterator other) const { return m_bit == other.m_bit; }
+ bool operator!=(Iterator other) const { return m_bit != other.m_bit; }
+ private:
+ IntTy m_val;
+ int m_bit;
+ };
+
+ BitSet() : m_val(0) {}
+ explicit BitSet(IntTy val) : m_val(val) {}
+ BitSet(std::initializer_list<int> init)
+ {
+ m_val = 0;
+ for (int bit : init)
+ m_val |= (IntTy)1 << bit;
+ }
+
+ static BitSet AllTrue(size_t count)
+ {
+ return BitSet(count == sizeof(IntTy)*8 ? ~(IntTy)0 : (((IntTy)1 << count) - 1));
+ }
+
+ Ref operator[](size_t bit) { return Ref(this, (IntTy)1 << bit); }
+ const Ref operator[](size_t bit) const { return (*const_cast<BitSet*>(this))[bit]; }
+ bool operator==(BitSet other) const { return m_val == other.m_val; }
+ bool operator!=(BitSet other) const { return m_val != other.m_val; }
+ bool operator<(BitSet other) const { return m_val < other.m_val; }
+ bool operator>(BitSet other) const { return m_val > other.m_val; }
+ BitSet operator|(BitSet other) const { return BitSet(m_val | other.m_val); }
+ BitSet operator&(BitSet other) const { return BitSet(m_val & other.m_val); }
+ BitSet operator^(BitSet other) const { return BitSet(m_val ^ other.m_val); }
+ BitSet operator~() const { return BitSet(~m_val); }
+ BitSet& operator|=(BitSet other) { return *this = *this | other; }
+ BitSet& operator&=(BitSet other) { return *this = *this & other; }
+ BitSet& operator^=(BitSet other) { return *this = *this ^ other; }
+ operator u32() = delete;
+ operator bool() { return m_val != 0; }
+
+ // Warning: Even though on modern CPUs this is a single fast instruction,
+ // Dolphin's official builds do not currently assume POPCNT support on x86,
+ // so slower explicit bit twiddling is generated. Still should generally
+ // be faster than a loop.
+ unsigned int Count() const { return CountSetBits(m_val); }
+
+ Iterator begin() const { Iterator it(m_val, 0); return ++it; }
+ Iterator end() const { return Iterator(m_val, -1); }
+
+ IntTy m_val;
+};
+
+} // Common
+
+typedef Common::BitSet<u8> BitSet8;
+typedef Common::BitSet<u16> BitSet16;
+typedef Common::BitSet<u32> BitSet32;
+typedef Common::BitSet<u64> BitSet64;
\ No newline at end of file