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#include "halt.h"
#include "heap.h"
#include "memory.h"
#include "font.h"
#include "interrupts.h"
#define PAGESIZE 0x1000
#define MAGIC ((void *) 0x69)
static heap_header init_free_ptr;
static heap_header *free_ptr = nil;
#ifdef DEBUG
void heap_check()
{
heap_header *h = free_ptr;
for (;;) {
if ((u64) h < 0x100000) {
print(S("heap corruption\n"));
asm volatile("int $1");
}
h = h->next;
if (h == free_ptr)
break;
}
}
#endif
void kfree(void *ptr)
{
ISR_UNSAFE
heap_check();
heap_header *h = ((heap_header *) ptr) - 1;
if (h->next != MAGIC)
panic(S("kfree: invalid pointer\n"));
heap_header *next = free_ptr->next;
free_ptr->next = h;
h->next = next;
heap_check();
}
void *try_kmalloc(usize size)
{
ISR_UNSAFE
heap_check();
for (heap_header *prev = free_ptr;; prev = prev->next) {
heap_header *h = prev->next;
if (h->size < size) {
if (h == free_ptr)
break;
else
continue;
}
if (h->size <= size + sizeof(heap_header)) {
prev->next = h->next;
} else {
// split
h->size -= size + sizeof(heap_header);
h = ((void *) h) + sizeof(heap_header) + h->size;
h->size = size;
}
h->next = MAGIC;
free_ptr = prev;
heap_check();
return h + 1;
}
return nil;
}
void *kmalloc(usize size)
{
ISR_UNSAFE
void *ptr = try_kmalloc(size);
if (ptr == nil)
panic(S("kmalloc: out of memory\n"));
return ptr;
}
void *krealloc(void *ptr, usize size)
{
ISR_UNSAFE
if (ptr == nil)
return kmalloc(size);
heap_header *h = ((heap_header *) ptr) - 1;
if (h->next != MAGIC)
panic(S("krealloc: invalid pointer\n"));
void *new = kmalloc(size);
lmemcpy(new, ptr, h->size);
kfree(h + 1);
return new;
}
void heap_init()
{
free_ptr = &init_free_ptr;
free_ptr->size = 0;
free_ptr->next = free_ptr;
}
void heap_add(void *ptr, usize size)
{
// discard blocks that are too small
if (size <= sizeof(heap_header))
return;
heap_header *h = ptr;
h->next = MAGIC;
h->size = size - sizeof(heap_header);
kfree(h + 1);
}
void heap_add_region(MemRegion *region)
{
switch (region->used) {
// region is reserved
case -1:
break;
// region is entirely free
case 0:
heap_add(region->start, region->size);
break;
// region is partly used
default: {
void *region_end = region->start + region->size;
// rounds up region->start to pagesize align
void *use_begin = (void *) ((u64) (region->start + PAGESIZE - 1) & ~(PAGESIZE - 1));
void *use_end = use_begin + region->used;
heap_add(region->start, use_begin - region->start);
heap_add(use_end, region_end - use_end);
}
}
region->used = -1; // just to be safe
}
heap_header *heap_get_free_ptr()
{
return free_ptr;
}
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