107 lines
3.5 KiB
C
107 lines
3.5 KiB
C
#include "kheap.h"
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/* The following function is a simple method to find the smallest hole that
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* fit user space request, since we will do this process many times, it's a good
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* idea to wrap it in a function */
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static int32_t find_smallest_hole(uint32_t size, uint8_t page_align, heap_t *heap) {
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uint32_t i = 0;
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while(i < heap->index.size) {
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header_t *header = (header_t*)lookup_ordered_list(i, &heap->index);
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if(page_align > 0) {
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uint32_t loc = (uint32_t)header;
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int32_t offset = 0;
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if((loc+sizeof(header_t)) & 0xFFFFF000 != 0) // Page aligned memory
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offset = 0x1000 - (loc+sizeof(header_t))%0x1000;
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int32_t hole_size = (int32_t)header->size - offset;
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if(hole_size >= (int32_t)size)
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break;
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} else if(header->size >= size)
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break;
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i++;
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}
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// Return something according to the iterator
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if(i == heap->index.size)
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return -1; // Nothing found
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else
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return i;
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}
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static int8_t header_t_less_than(void *a, void *b) {
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return (((header_t*)a)->size < ((header_t*)b)->size)?1:0;
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}
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heap_t *create_heap(uint32_t start, uint32_t end, uint32_t max, uint8_t supervisor, uint8_t readonly) {
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heap_t *heap = (heap_t*)kmalloc(sizeof(heap_t)); //TODO: implement kmalloc
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ASSERT(start%0x1000 == 0);
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ASSERT(end%0x1000 == 0);
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// Init heap's index
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heap->index = place_ordered_list((void*)start, HEAP_INDEX_SIZE, &header_t_less_than);
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// Shift start address to the corrent position, where we can put on data
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start += sizeof(type_t)*HEAP_INDEX_SIZE;
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// Check if start address is page-aligned
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if(start & 0xFFFFF000 != 0) {
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start &= 0xFFFFF000;
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start += 0x1000;
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}
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// Fill the heap structure with start, end and max addresses
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heap->start_address = start;
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heap->end_address = end;
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heap->max_address = max;
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heap->supervisor = supervisor;
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heap->readonly = readonly;
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// Let's create one large hole in the new index
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header_t *hole = (header_t*)start;
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hole->size = end-start;
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hole->magic = HEAP_MAGIC;
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hole->is_hole = 1;
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insert_ordered_list((void*)hole, &heap->index);
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return heap;
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}
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static void expand(uint32_t new_size, heap_t *heap) {
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// Before anything else let's check that new size is greater than older one
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ASSERT(new_size > heap->end_address - heap->start_address);
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if(new_size&0xFFFFF000 != 0) {
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new_size &= 0xFFFFF000;
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new_size += 0x1000;
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}
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// Check if new size is not greater than maximum size
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ASSERT(heap->start_address+new_size <= heap->max_address);
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uint32_t old_size = heap->end_address-heap->start_address;
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uint32_t i = old_size;
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while(i < new_size) {
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alloc_frame(get_page(heap->start_address+i, 1, kernel_directory), // FIXME:
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(heap->supervisor)?1:0, (heap->readonly)?0:1);
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}
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}
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static uint32_t contract(uint32_t new_size, heap_t *heap) {
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// This function will be literally the opposite of the previous one
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ASSERT(new_size < heap->end_address-heap->start_address);
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if(new_size&0x1000) {
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new_size &= 0x1000;
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new_size += 0x1000;
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}
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if(new_size < HEAP_MIN_SIZE)
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new_size = HEAP_MIN_SIZE;
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uint32_t old_size = heap->end_address-heap->start_address;
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uint32_t i = old_size - 0x1000;
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while(new_size < i) {
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free_frame(get_page(heap->start_address+i, 0, kernel_directory));
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i -= 0x1000;
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}
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heap->end_address = heap->start_address + new_size;
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return new_size;
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}
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