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AK: Add Bitmap::count_in_range and Bitmap::fill_range

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Tom 2020-09-06 08:06:35 -06:00 • committed by Andreas Kling
parent cd2815ed87
commit efac3d27d2
2 changed files with 161 additions and 0 deletions
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98
AK/Bitmap.h
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@ -103,6 +103,57 @@ public:
}
}
size_t count_slow(bool value) const
{
return count_in_range(0, m_size, value);
}
size_t count_in_range(size_t start, size_t len, bool value) const
{
ASSERT(start < m_size);
ASSERT(start + len <= m_size);
if (len == 0)
return 0;
static const u8 bitmask_first_byte[8] = { 0xFF, 0xFE, 0xFC, 0xF8, 0xF0, 0xE0, 0xC0, 0x80 };
static const u8 bitmask_last_byte[8] = { 0x0, 0x1, 0x3, 0x7, 0xF, 0x1F, 0x3F, 0x7F };
size_t count;
const u8* first = &m_data[start / 8];
const u8* last = &m_data[(start + len) / 8];
u8 byte = *first;
byte &= bitmask_first_byte[start % 8];
if (first == last) {
byte &= bitmask_last_byte[(start + len) % 8];
count = __builtin_popcount(byte);
} else {
count = __builtin_popcount(byte);
byte = *last;
byte &= bitmask_last_byte[(start + len) % 8];
count += __builtin_popcount(byte);
if (++first < last) {
const u32* ptr32 = (const u32*)(((FlatPtr)first + sizeof(u32) - 1) & ~(sizeof(u32) - 1));
if ((const u8*)ptr32 > last)
ptr32 = (const u32*)last;
while (first < (const u8*)ptr32) {
count += __builtin_popcount(*first);
first++;
}
const u32* last32 = (const u32*)((FlatPtr)last & ~(sizeof(u32) - 1));
while (ptr32 < last32) {
count += __builtin_popcountl(*ptr32);
ptr32++;
}
for (first = (const u8*)ptr32; first < last; first++)
count += __builtin_popcount(*first);
}
}
if (!value)
count = len - count;
return count;
}
u8* data() { return m_data; }
const u8* data() const { return m_data; }
@ -127,6 +178,53 @@ public:
}
}
template<bool VALUE>
void fill_range(size_t start, size_t len)
{
ASSERT(start < m_size);
ASSERT(start + len <= m_size);
if (len == 0)
return;
static const u8 bitmask_first_byte[8] = { 0xFF, 0xFE, 0xFC, 0xF8, 0xF0, 0xE0, 0xC0, 0x80 };
static const u8 bitmask_last_byte[8] = { 0x0, 0x1, 0x3, 0x7, 0xF, 0x1F, 0x3F, 0x7F };
u8* first = &m_data[start / 8];
u8* last = &m_data[(start + len) / 8];
u8 byte_mask = bitmask_first_byte[start % 8];
if (first == last) {
byte_mask &= bitmask_last_byte[(start + len) % 8];
if constexpr (VALUE)
*first |= byte_mask;
else
*first &= ~byte_mask;
} else {
if constexpr (VALUE)
*first |= byte_mask;
else
*first &= ~byte_mask;
byte_mask = bitmask_last_byte[(start + len) % 8];
if constexpr (VALUE)
*last |= byte_mask;
else
*last &= ~byte_mask;
if (++first < last) {
if constexpr (VALUE)
__builtin_memset(first, 0xFF, last - first);
else
__builtin_memset(first, 0x0, last - first);
}
}
}
void fill_range(size_t start, size_t len, bool value)
{
if (value)
fill_range<true>(start, len);
else
fill_range<false>(start, len);
}
void fill(bool value)
{
__builtin_memset(m_data, value ? 0xff : 0x00, size_in_bytes());