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//! Contiguous Page Allocation
const bitmap = @import("../bitmap/bitmap.zig");
const state = @import("../state.zig");
const common = @import("../../../common/common.zig");
const AllocationError = common.errors.memory.AllocationError;
pub fn allocate_contiguous(page_count: u64) AllocationError!u64 {
if (page_count == 0) {
return AllocationError.InvalidSize;
}
const pmm_state = state.get_state();
if (pmm_state.free_pages < page_count) {
return AllocationError.OutOfMemory;
}
const start_page = bitmap.find_contiguous_clear(
pmm_state.bitmap,
0,
pmm_state.total_pages,
page_count,
) orelse return AllocationError.OutOfMemory;
bitmap.set_range(pmm_state.bitmap, start_page, page_count);
pmm_state.free_pages -= page_count;
pmm_state.used_pages += page_count;
return start_page << 12;
}
pub fn allocate_contiguous_zeroed(page_count: u64) AllocationError!u64 {
const physical_address = try allocate_contiguous(page_count);
const virtual_address = physical_address + common.constants.memory.layout.physmap_base;
const total_bytes = page_count * 4096;
const page_ptr: [*]u8 = @ptrFromInt(virtual_address);
@memset(page_ptr[0..total_bytes], 0);
return physical_address;
}
pub fn allocate_aligned(page_count: u64, alignment_pages: u64) AllocationError!u64 {
if (page_count == 0 or alignment_pages == 0) {
return AllocationError.InvalidSize;
}
const pmm_state = state.get_state();
if (pmm_state.free_pages < page_count) {
return AllocationError.OutOfMemory;
}
var search_start: u64 = 0;
while (search_start + page_count <= pmm_state.total_pages) {
const aligned_start = (search_start + alignment_pages - 1) / alignment_pages * alignment_pages;
if (aligned_start + page_count > pmm_state.total_pages) {
break;
}
var found = true;
var check_index: u64 = 0;
while (check_index < page_count) : (check_index += 1) {
if (bitmap.test_bit(pmm_state.bitmap, aligned_start + check_index)) {
found = false;
search_start = aligned_start + check_index + 1;
break;
}
}
if (found) {
bitmap.set_range(pmm_state.bitmap, aligned_start, page_count);
pmm_state.free_pages -= page_count;
pmm_state.used_pages += page_count;
return aligned_start << 12;
}
}
return AllocationError.OutOfMemory;
}
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