jak-project/common/util/BitUtils.h

98 lines
1.9 KiB
C++

#pragma once
#include <optional>
#include "common/common_types.h"
#include "common/util/Assert.h"
#include "common/util/Range.h"
constexpr int BITS_PER_BYTE = 8;
template <typename T>
std::optional<Range<int>> get_bit_range(T value) {
enum State { INITIAL_ZEROS, ONES, TRAILING_ZEROS } state = INITIAL_ZEROS;
int start_bit = 0;
int end_bit = 0;
int max_bit = BITS_PER_BYTE * sizeof(T);
for (int i = 0; i < max_bit; i++) {
bool bit = (value) & (T(1) << i);
if (state == INITIAL_ZEROS) {
if (bit) {
start_bit = i;
state = ONES;
}
} else if (state == ONES) {
if (!bit) {
end_bit = i;
state = TRAILING_ZEROS;
}
} else if (state == TRAILING_ZEROS) {
if (bit) {
return std::nullopt;
}
}
}
if (state == INITIAL_ZEROS) {
return std::nullopt;
} else if (state == ONES) {
end_bit = max_bit;
}
return Range<int>{start_bit, end_bit};
}
/*!
* Note: this only works on numbers that are greater than or equal to 0.
*/
template <typename T>
std::optional<int> get_power_of_two(T in) {
if (in == 0) {
return std::nullopt;
}
if ((in & (in - 1)) == 0) {
for (int i = 0; i < 64; i++) {
if (in == (T(1) << i)) {
return i;
}
}
ASSERT(false);
} else {
return std::nullopt;
}
}
bool integer_fits(s64 in, int size, bool is_signed);
u32 float_as_u32(float x);
template <typename T>
T align16(T in) {
return (in + 15) & (~T(15));
}
template <typename T>
T align8(T in) {
return (in + 7) & (~T(7));
}
template <typename T>
T align4(T in) {
return (in + 3) & (~T(3));
}
template <typename T>
T align64(T in) {
return (in + 63) & (~T(63));
}
inline u32 count_leading_zeros_u32(u32 in) {
#if defined(__GNUC__) || defined(__clang__)
return __builtin_clz(in);
#else
unsigned long result;
_BitScanReverse(&result, in);
return result;
#endif
}