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base: let bit allocator use fine-grained sizes 

Ref #1588
This commit is contained in:
Stefan Kalkowski 2015-06-25 16:24:42 +02:00 committed by Christian Helmuth
parent 6552d47e60
commit b856bfdfcd
2 changed files with 33 additions and 24 deletions
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18
repos/base/include/util/bit_allocator.h
View File

@ -25,8 +25,17 @@ class Genode::Bit_allocator
{
protected:
addr_t _next;
Bit_array<BITS> _array;
enum {
BITS_PER_BYTE = 8UL,
BITS_PER_WORD = sizeof(addr_t) * BITS_PER_BYTE,
BITS_ALIGNED = (BITS + BITS_PER_WORD - 1UL)
& ~(BITS_PER_WORD - 1UL),
};
using Array = Bit_array<BITS_ALIGNED>;
addr_t _next;
Array _array;
/**
* Reserve consecutive number of bits
@ -44,7 +53,8 @@ class Genode::Bit_allocator
class Out_of_indices : Exception {};
Bit_allocator() : _next(0) { }
Bit_allocator() : _next(0) {
_reserve(BITS, BITS_ALIGNED - BITS); }
addr_t alloc(size_t const num_log2 = 0)
{
@ -62,7 +72,7 @@ class Genode::Bit_allocator
_next = i + step;
return i;
}
} catch (typename Bit_array<BITS>::Invalid_index_access) { }
} catch (typename Array::Invalid_index_access) { }
max = _next;
_next = 0;

39
repos/base/include/util/bit_array.h
View File

@ -35,39 +35,38 @@ class Genode::Bit_array_base
class Invalid_clear : public Exception {};
class Invalid_set : public Exception {};
protected:
static constexpr size_t _BITS_PER_BYTE = 8UL;
static constexpr size_t _BITS_PER_WORD = sizeof(addr_t) *
_BITS_PER_BYTE;
private:
enum {
BITS_PER_BYTE = 8UL,
BITS_PER_WORD = sizeof(addr_t) * BITS_PER_BYTE
};
unsigned _bit_cnt;
unsigned _word_cnt;
addr_t *_words;
addr_t _word(addr_t index) const {
return index / _BITS_PER_WORD; }
return index / BITS_PER_WORD; }
void _check_range(addr_t const index,
addr_t const width) const
{
if ((index >= _word_cnt * _BITS_PER_WORD) ||
width > _word_cnt * _BITS_PER_WORD ||
_word_cnt * _BITS_PER_WORD - width < index)
if ((index >= _word_cnt * BITS_PER_WORD) ||
width > _word_cnt * BITS_PER_WORD ||
_word_cnt * BITS_PER_WORD - width < index)
throw Invalid_index_access();
}
addr_t _mask(addr_t const index, addr_t const width,
addr_t &rest) const
{
addr_t const shift = index - _word(index) * _BITS_PER_WORD;
addr_t const shift = index - _word(index) * BITS_PER_WORD;
rest = width + shift > _BITS_PER_WORD ?
width + shift - _BITS_PER_WORD : 0;
rest = width + shift > BITS_PER_WORD ?
width + shift - BITS_PER_WORD : 0;
return (width >= _BITS_PER_WORD) ? ~0UL << shift
return (width >= BITS_PER_WORD) ? ~0UL << shift
: ((1UL << width) - 1) << shift;
}
@ -90,7 +89,7 @@ class Genode::Bit_array_base
_words[word] |= mask;
}
index = (_word(index) + 1) * _BITS_PER_WORD;
index = (_word(index) + 1) * BITS_PER_WORD;
width = rest;
} while (rest);
}
@ -99,10 +98,10 @@ class Genode::Bit_array_base
Bit_array_base(unsigned bits, addr_t *addr, bool clear)
: _bit_cnt(bits),
_word_cnt(_bit_cnt / _BITS_PER_WORD),
_word_cnt(_bit_cnt / BITS_PER_WORD),
_words(addr)
{
if (!bits || bits % _BITS_PER_WORD) throw Invalid_bit_count();
if (!bits || bits % BITS_PER_WORD) throw Invalid_bit_count();
if (clear) memset(_words, 0, sizeof(addr_t)*_word_cnt);
}
@ -120,7 +119,7 @@ class Genode::Bit_array_base
do {
mask = _mask(index, width, rest);
used = _words[_word(index)] & mask;
index = (_word(index) + 1) * _BITS_PER_WORD;
index = (_word(index) + 1) * BITS_PER_WORD;
width = rest;
} while (!used && rest);
@ -140,9 +139,9 @@ class Genode::Bit_array : public Bit_array_base
{
private:
static constexpr size_t _WORDS = BITS / _BITS_PER_WORD;
static constexpr size_t _WORDS = BITS / BITS_PER_WORD;
static_assert(BITS % _BITS_PER_WORD == 0,
static_assert(BITS % BITS_PER_WORD == 0,
"Count of bits need to be word aligned!");
addr_t _array[_WORDS];