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Basic support for allocation of block < 33M

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This commit is contained in:
Baptiste Wicht 2014-02-06 22:39:06 +01:00
parent abd1848c1c
commit 1b3ed9ff5a
1 changed files with 51 additions and 21 deletions
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72
kernel/src/virtual_allocator.cpp
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@ -18,7 +18,6 @@ constexpr const size_t last_virtual_address = virtual_allocator::kernel_virtual_
constexpr const size_t managed_space = last_virtual_address - first_virtual_address;
constexpr const size_t unit = paging::PAGE_SIZE;
size_t next_virtual_address = first_virtual_address;
size_t allocated_pages = first_virtual_address / paging::PAGE_SIZE;
struct static_bitmap {
@ -74,6 +73,17 @@ struct static_bitmap {
return 0;
}
size_t free_word() const {
for(size_t w = 0; w < words; ++w){
if(data[w] == ~static_cast<data_type>(0)){
return w * bits_per_word;
}
}
//TODO Use an assert here
return 0;
}
bool is_set(size_t bit) const {
return data[word_offset(bit)] & bit_mask(bit);
}
@ -135,11 +145,6 @@ size_t level_size(size_t level){
return size;
}
size_t get_free_block_index(size_t level){
auto& bitmap = bitmaps[level];
return bitmap.free_bit();
}
} //end of anonymous namespace
void virtual_allocator::init(){
@ -211,7 +216,7 @@ void free_up(size_t level, size_t index){
}
}
uintptr_t compute_address(size_t level, size_t index){
uintptr_t block_start(size_t level, size_t index){
return first_virtual_address + index * level_size(level) * unit;
}
@ -219,31 +224,56 @@ size_t get_block_index(size_t address, size_t level){
return (address - first_virtual_address) / (level_size(level) * unit);
}
void mark_used(size_t l, size_t index){
//The current level block is not free anymore
bitmaps[l].unset(index);
//Mark all sub blocks as taken
taken_down(l, index);
//Mark all up blocks as taken
taken_up(l, index);
}
size_t virtual_allocator::allocate(size_t pages){
//TODO Do something if not enough pages
//TODO Return 0 if not enough pages
allocated_pages += pages;
if(pages > max_block){
//TODO Special algorithm for big pages
return 0;
if(pages > max_block * static_bitmap::bits_per_word){
//That means we try to allocate more than 33M at the same time
//probably not a good idea
//TODO Implement it all the same
return 0;
} else {
auto l = bitmaps.size() - 1;
auto index = bitmaps[l].free_word();
auto address = block_start(l, index);
//TODO check also address + size
if(address >= last_virtual_address){
return 0;
}
//Mark all bits of the word as used
for(size_t b = 0; b < static_bitmap::bits_per_word; ++b){
mark_used(l, index + b);
}
return address;
}
} else {
auto l = level(pages);
auto index = get_free_block_index(l);
auto address = compute_address(l, index);
auto index = bitmaps[l].free_bit();
auto address = block_start(l, index);
if(address > last_virtual_address){
//TODO check also address + size
if(address >= last_virtual_address){
return 0;
}
//The current level block is not free anymore
bitmaps[l].unset(index);
//Mark all sub blocks as taken
taken_down(l, index);
//Mark all up blocks as taken
taken_up(l, index);
mark_used(l, index);
return address;
}