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AK: Add find_first_{set,unset} and grow methods to Bitmap

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This commit is contained in:
Conrad Pankoff 2019-06-11 22:50:41 +10:00 committed by Andreas Kling
parent fa204aeb77
commit f7dce4765c
Notes: sideshowbarker 2024-07-19 13:39:02 +09:00 
Author: https://github.com/deoxxa
Commit: https://github.com/SerenityOS/serenity/commit/f7dce4765c4
Pull-request: https://github.com/SerenityOS/serenity/pull/224
Reviewed-by: https://github.com/awesomekling
1 changed files with 67 additions and 0 deletions
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67
AK/Bitmap.h
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@ -20,6 +20,11 @@ public:
return Bitmap(size, default_value);
}
static Bitmap create()
{
return Bitmap();
}
~Bitmap()
{
if (m_owned)
@ -45,12 +50,74 @@ public:
byte* data() { return m_data; }
const byte* data() const { return m_data; }
void grow(int size, bool default_value)
{
ASSERT(size > m_size);
auto previous_size_bytes = size_in_bytes();
auto previous_size = m_size;
auto previous_data = m_data;
m_size = size;
m_data = reinterpret_cast<byte*>(kmalloc(size_in_bytes()));
fill(default_value);
if (previous_data != nullptr) {
memcpy(m_data, previous_data, previous_size_bytes);
if ((previous_size % 8) != 0) {
if (default_value)
m_data[previous_size_bytes - 1] |= (0xff >> (previous_size % 8));
else
m_data[previous_size_bytes - 1] &= ~(0xff >> (previous_size % 8));
}
kfree(previous_data);
}
}
void fill(bool value)
{
memset(m_data, value ? 0xff : 0x00, size_in_bytes());
}
int find_first_set() const
{
int i = 0;
while (i < m_size / 8 && m_data[i] == 0x00)
i++;
int j = 0;
for (j = i * 8; j < m_size; j++)
if (get(j))
return j;
return -1;
}
int find_first_unset() const
{
int i = 0;
while (i < m_size / 8 && m_data[i] == 0xff)
i++;
int j = 0;
for (j = i * 8; j < m_size; j++)
if (!get(j))
return j;
return -1;
}
private:
explicit Bitmap()
: m_size(0)
, m_owned(true)
{
m_data = nullptr;
}
explicit Bitmap(int size, bool default_value)
: m_size(size)
, m_owned(true)