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Codechange: replace FIND_FIRST_BIT/FindFirstBit2x64 with FindFirstBit

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Rubidium
2024-01-18 19:40:49 +01:00
committed by rubidium42
parent 8faaedeff9
commit 6b21368bc2
13 changed files with 21 additions and 81 deletions
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45
src/core/bitmath_func.hpp
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@@ -183,45 +183,6 @@ inline T ToggleBit(T &x, const uint8_t y)
return x = (T)(x ^ ((T)1U << y));
}
/** Lookup table to check which bit is set in a 6 bit variable */
extern const uint8_t _ffb_64[64];
/**
* Returns the first non-zero bit in a 6-bit value (from right).
*
* Returns the position of the first bit that is not zero, counted from the
* LSB. Ie, 110100 returns 2, 000001 returns 0, etc. When x == 0 returns
* 0.
*
* @param x The 6-bit value to check the first zero-bit
* @return The first position of a bit started from the LSB or 0 if x is 0.
*/
#define FIND_FIRST_BIT(x) _ffb_64[(x)]
/**
* Finds the position of the first non-zero bit in an integer.
*
* This function returns the position of the first bit set in the
* integer. It does only check the bits of the bitmask
* 0x3F3F (0011111100111111) and checks only the
* bits of the bitmask 0x3F00 if and only if the
* lower part 0x00FF is 0. This results the bits at 0x00C0 must
* be also zero to check the bits at 0x3F00.
*
* @param value The value to check the first bits
* @return The position of the first bit which is set
* @see FIND_FIRST_BIT
*/
inline uint8_t FindFirstBit2x64(const int value)
{
if ((value & 0xFF) == 0) {
return FIND_FIRST_BIT((value >> 8) & 0x3F) + 8;
} else {
return FIND_FIRST_BIT(value & 0x3F);
}
}
/**
* Search the first set bit in a value.
* When no bit is set, it returns 0.
@@ -234,7 +195,11 @@ constexpr uint8_t FindFirstBit(T x)
{
if (x == 0) return 0;
return std::countr_zero(x);
if constexpr (std::is_enum_v<T>) {
return std::countr_zero<std::underlying_type_t<T>>(x);
} else {
return std::countr_zero(x);
}
}
/**