cutlass/include/cutlass/integer_subbyte.h

255 lines
7.2 KiB
C++

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/*!
\file
\brief Defines a class for using integer types smaller than one byte in host or
device code.
*/
/*
Note: CUTLASS 3x increases the host compiler requirements to C++17. However, certain
existing integrations of CUTLASS require C++11 host compilers.
Until this requirement can be lifted, certain headers with this annotation are required
to be remain consistent with C++11 syntax.
C++11 compatibility is enforced by `cutlass_test_unit_core_cpp11`.
*/
#pragma once
#if defined(__CUDACC_RTC__)
#include <cuda/std/cstdint>
#else
#include <cstdint>
#endif
#include "cutlass/cutlass.h"
#include "cutlass/numeric_size.h"
#include "cutlass/platform/platform.h"
namespace cutlass {
///////////////////////////////////////////////////////////////////////////////////////////////////
/// 4-bit signed integer type
template <int Bits, bool Signed = true>
struct integer_subbyte {
/// Number of bits
static int const kBits = Bits;
/// Whether type is signed
static bool const kSigned = Signed;
/// External type
using T = typename platform::conditional<kSigned, int, unsigned>::type;
/// Storage type
using Storage = uint8_t;
/// Bitmask used to truncate from larger integers
static Storage const kMask = Storage((1 << kBits) - 1);
//
// Data members
//
Storage storage;
//
// Methods
//
/// No operation
integer_subbyte() = default;
/// Conversion from integer type
CUTLASS_HOST_DEVICE
integer_subbyte(int value)
: storage(reinterpret_cast<Storage const &>(value) & kMask) {}
CUTLASS_HOST_DEVICE
integer_subbyte(unsigned value)
: storage(reinterpret_cast<Storage const &>(value) & kMask) {}
CUTLASS_HOST_DEVICE
integer_subbyte(double value) {
T tmp = static_cast<T>(value);
storage = Storage(reinterpret_cast<unsigned const &>(tmp) & kMask);
}
///
CUTLASS_HOST_DEVICE
operator T() const {
if (kSigned) {
// Sign extend
if (storage & Storage(1 << (kBits - 1))) {
return T(storage) | ~T(kMask);
}
}
return T(storage);
}
/// Equality
CUTLASS_HOST_DEVICE
bool operator==(integer_subbyte const &rhs) const {
return storage == rhs.storage;
}
/// Inequality
CUTLASS_HOST_DEVICE
bool operator!=(integer_subbyte const &rhs) const {
return storage != rhs.storage;
}
/// Less than or equal
CUTLASS_HOST_DEVICE
bool operator<=(integer_subbyte const &rhs) const {
if (kSigned) {
if (storage & (1 << (kBits - 1))) {
return !(rhs.storage < storage);
}
}
return storage <= rhs.storage;
}
/// Less than
CUTLASS_HOST_DEVICE
bool operator<(integer_subbyte const &rhs) const {
if (kSigned) {
if (storage & (1 << (kBits - 1))) {
return !(rhs.storage <= storage);
}
}
return storage < rhs.storage;
}
/// Greater than or equal
CUTLASS_HOST_DEVICE
bool operator>=(integer_subbyte const &rhs) const {
return !(*this < rhs);
}
/// Greater than
CUTLASS_HOST_DEVICE
bool operator>(integer_subbyte const &rhs) const {
return !(*this <= rhs);
}
};
///////////////////////////////////////////////////////////////////////////////////////////////////
/// 1-bit Unsigned integer type
using uint1b_t = integer_subbyte<1, false>;
/// 2-bit Integer type
using int2b_t = integer_subbyte<2, true>;
/// 2-bit Unsigned integer type
using uint2b_t = integer_subbyte<2, false>;
/// 4-bit Integer type
using int4b_t = integer_subbyte<4, true>;
/// 4-bit Unsigned integer type
using uint4b_t = integer_subbyte<4, false>;
///////////////////////////////////////////////////////////////////////////////////////////////////
/// Defines the size of an element in bits - specialized for uint1b_t
template <>
struct sizeof_bits<uint1b_t> {
static int const value = 1;
};
/// Defines the size of an element in bits - specialized for int2b_t
template <>
struct sizeof_bits<int2b_t> {
static int const value = 2;
};
/// Defines the size of an element in bits - specialized for uint2b_t
template <>
struct sizeof_bits<uint2b_t> {
static int const value = 2;
};
/// Defines the size of an element in bits - specialized for int4b_t
template <>
struct sizeof_bits<int4b_t> {
static int const value = 4;
};
/// Defines the size of an element in bits - specialized for uint4b_t
template <>
struct sizeof_bits<uint4b_t> {
static int const value = 4;
};
///////////////////////////////////////////////////////////////////////////////////////////////////
namespace platform {
template <>
struct numeric_limits<cutlass::int4b_t> {
CUTLASS_HOST_DEVICE
static cutlass::int4b_t const lowest() noexcept { return -8;}
CUTLASS_HOST_DEVICE
static cutlass::int4b_t const max() noexcept { return 7;}
static constexpr bool is_integer = true;
};
template <>
struct numeric_limits<cutlass::uint4b_t> {
CUTLASS_HOST_DEVICE
static cutlass::uint4b_t const lowest() noexcept { return 0;}
CUTLASS_HOST_DEVICE
static cutlass::uint4b_t const max() noexcept { return 15;}
static constexpr bool is_integer = true;
};
template <>
struct numeric_limits<cutlass::uint1b_t> {
CUTLASS_HOST_DEVICE
static cutlass::uint1b_t const lowest() noexcept { return 0;}
CUTLASS_HOST_DEVICE
static cutlass::uint1b_t const max() noexcept { return 1;}
static constexpr bool is_integer = true;
};
///////////////////////////////////////////////////////////////////////////////////////////////////
} // namespace platform
} // namespace cutlass