diff options
Diffstat (limited to '3rdparty/bgfx/3rdparty/spirv-tools/source/util/bitutils.h')
-rw-r--r-- | 3rdparty/bgfx/3rdparty/spirv-tools/source/util/bitutils.h | 93 |
1 files changed, 92 insertions, 1 deletions
diff --git a/3rdparty/bgfx/3rdparty/spirv-tools/source/util/bitutils.h b/3rdparty/bgfx/3rdparty/spirv-tools/source/util/bitutils.h index 17d61df90ab..9ced2f9621c 100644 --- a/3rdparty/bgfx/3rdparty/spirv-tools/source/util/bitutils.h +++ b/3rdparty/bgfx/3rdparty/spirv-tools/source/util/bitutils.h @@ -15,8 +15,10 @@ #ifndef SOURCE_UTIL_BITUTILS_H_ #define SOURCE_UTIL_BITUTILS_H_ +#include <cassert> #include <cstdint> #include <cstring> +#include <type_traits> namespace spvtools { namespace utils { @@ -31,6 +33,14 @@ Dest BitwiseCast(Src source) { return dest; } +// Calculates the bit width of the integer type |T|. +template <typename T> +struct IntegerBitWidth { + static_assert(std::is_integral<T>::value, "Integer type required"); + static const size_t kBitsPerByte = 8; + static const size_t get = sizeof(T) * kBitsPerByte; +}; + // SetBits<T, First, Num> returns an integer of type <T> with bits set // for position <First> through <First + Num - 1>, counting from the least // significant bit. In particular when Num == 0, no positions are set to 1. @@ -38,7 +48,7 @@ Dest BitwiseCast(Src source) { // a bit that will not fit in the underlying type is set. template <typename T, size_t First = 0, size_t Num = 0> struct SetBits { - static_assert(First < sizeof(T) * 8, + static_assert(First < IntegerBitWidth<T>::get, "Tried to set a bit that is shifted too far."); const static T get = (T(1) << First) | SetBits<T, First + 1, Num - 1>::get; }; @@ -49,6 +59,11 @@ struct SetBits<T, Last, 0> { }; // This is all compile-time so we can put our tests right here. +static_assert(IntegerBitWidth<uint32_t>::get == 32, "IntegerBitWidth mismatch"); +static_assert(IntegerBitWidth<int32_t>::get == 32, "IntegerBitWidth mismatch"); +static_assert(IntegerBitWidth<uint64_t>::get == 64, "IntegerBitWidth mismatch"); +static_assert(IntegerBitWidth<uint8_t>::get == 8, "IntegerBitWidth mismatch"); + static_assert(SetBits<uint32_t, 0, 0>::get == uint32_t(0x00000000), "SetBits failed"); static_assert(SetBits<uint32_t, 0, 1>::get == uint32_t(0x00000001), @@ -90,6 +105,82 @@ size_t CountSetBits(T word) { return count; } +// Checks if the bit at the |position| is set to '1'. +// Bits zero-indexed starting at the least significant bit. +// |position| must be within the bit width of |T|. +template <typename T> +bool IsBitAtPositionSet(T word, size_t position) { + static_assert(std::is_integral<T>::value, "Integer type required"); + static_assert(std::is_unsigned<T>::value, "Unsigned type required"); + assert(position < IntegerBitWidth<T>::get && + "position must be less than the bit width"); + return word & T(T(1) << position); +} + +// Returns a value obtained by setting a range of adjacent bits of |word| to +// |value|. Affected bits are within the range: +// [first_position, first_position + num_bits_to_mutate), +// assuming zero-based indexing starting at the least +// significant bit. Bits to mutate must be within the bit width of |T|. +template <typename T> +T MutateBits(T word, size_t first_position, size_t num_bits_to_mutate, + bool value) { + static_assert(std::is_integral<T>::value, "Integer type required"); + static_assert(std::is_unsigned<T>::value, "Unsigned type required"); + static const size_t word_bit_width = IntegerBitWidth<T>::get; + assert(first_position < word_bit_width && + "Mutated bits must be within bit width"); + assert(first_position + num_bits_to_mutate <= word_bit_width && + "Mutated bits must be within bit width"); + if (num_bits_to_mutate == 0) { + return word; + } + + const T all_ones = ~T(0); + const size_t num_unaffected_low_bits = first_position; + const T unaffected_low_mask = + T(T(all_ones >> num_unaffected_low_bits) << num_unaffected_low_bits); + + const size_t num_unaffected_high_bits = + word_bit_width - (first_position + num_bits_to_mutate); + const T unaffected_high_mask = + T(T(all_ones << num_unaffected_high_bits) >> num_unaffected_high_bits); + + const T mutation_mask = unaffected_low_mask & unaffected_high_mask; + if (value) { + return word | mutation_mask; + } + return word & T(~mutation_mask); +} + +// Returns a value obtained by setting the |num_bits_to_set| highest bits to +// '1'. |num_bits_to_set| must be not be greater than the bit width of |T|. +template <typename T> +T SetHighBits(T word, size_t num_bits_to_set) { + if (num_bits_to_set == 0) { + return word; + } + const size_t word_bit_width = IntegerBitWidth<T>::get; + assert(num_bits_to_set <= word_bit_width && + "Can't set more bits than bit width"); + return MutateBits(word, word_bit_width - num_bits_to_set, num_bits_to_set, + true); +} + +// Returns a value obtained by setting the |num_bits_to_set| highest bits to +// '0'. |num_bits_to_set| must be not be greater than the bit width of |T|. +template <typename T> +T ClearHighBits(T word, size_t num_bits_to_set) { + if (num_bits_to_set == 0) { + return word; + } + const size_t word_bit_width = IntegerBitWidth<T>::get; + assert(num_bits_to_set <= word_bit_width && + "Can't clear more bits than bit width"); + return MutateBits(word, word_bit_width - num_bits_to_set, num_bits_to_set, + false); +} + } // namespace utils } // namespace spvtools |