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#include "heap.h"
#include <jove/memory.h>
#include <jove/jove.h>
#include <stdlib.h>
#include <string.h>
static heap_bin_t *freelist_tail;
uintptr_t __heap_start;
uintptr_t __heap_end;
#define HEAP_BIN_SIZE(bin) (bin->size_taken & (~1ULL))
#define HEAP_BIN_TAKEN(bin) (bin->size_taken & 1)
#define HEAP_BIN_AFTER(bin) ((heap_bin_t*)((uintptr_t)bin->data + HEAP_BIN_SIZE(bin) + sizeof(uintptr_t)))
#define HEAP_BIN_BEFORE(bin) ((heap_bin_t*)*((uintptr_t*)bin - 1))
static void
heap_grow(uintptr_t to)
{
jove_mem_ensure_range(__heap_end, to);
__heap_end = to;
}
static heap_bin_t*
heap_newbin(uintptr_t at, size_t size, heap_bin_t *next)
{
uintptr_t headat = (at + sizeof(heap_bin_t) + size);
uintptr_t endat = headat + sizeof(uintptr_t);
if(endat > __heap_end) heap_grow(endat);
heap_bin_t *newbin = (heap_bin_t*)at;
newbin->size_taken = size;
newbin->next = next;
*((uintptr_t*)headat) = at;
return newbin;
}
static heap_bin_t*
heap_find_bestfit(size_t rsize)
{
heap_bin_t *best = freelist_tail;
if(best == NULL) return NULL;
size_t bestsize = best->size_taken;
for(heap_bin_t *bin = best->next; bin; bin = bin->next)
{
if(bin->size_taken < rsize) continue;
if(bin->size_taken < bestsize) {
best = bin;
bestsize = bin->size_taken;
}
}
return best;
}
static void
heap_split(heap_bin_t *bin, size_t splitsize)
{
size_t size_diff = bin->size_taken - splitsize;
if(size_diff < LIBC_HEAP_MINSPLIT) return;
size_t newsize = size_diff - sizeof(heap_bin_t) - sizeof(uintptr_t);
uintptr_t newat = ((uintptr_t)bin->data) + splitsize + sizeof(uintptr_t);
jove_kprintf("Split %p to %p [%x]\n", bin, newat, newsize);
bin->size_taken = splitsize;
freelist_tail = heap_newbin(newat, newsize, freelist_tail);
}
static void*
heap_alloc(size_t size)
{
if(size & 1) size++;
if(size < LIBC_HEAP_MINALLOC) size = LIBC_HEAP_MINALLOC;
heap_bin_t *bestfit = heap_find_bestfit(size);
if(bestfit == NULL) {
bestfit = heap_newbin(__heap_end, size, NULL);
}else{
if(bestfit == freelist_tail) {
freelist_tail = bestfit->next;
}
size_t bestsize = bestfit->size_taken;
if(bestsize < size) {
jove_kprintf("Growing bin %p [%x] to %x\n", bestfit, bestsize, size);
heap_newbin((uintptr_t)bestfit, size, NULL);
}else if(bestsize > size) {
heap_split(bestfit, size);
}
}
bestfit->size_taken |= 1;
return bestfit->data;
}
static void
heap_free(void *ptr)
{
uintptr_t binptr = (uintptr_t)ptr - sizeof(heap_bin_t);
if(binptr > __heap_end || binptr < __heap_start) return;
heap_bin_t *bin = (heap_bin_t*)binptr;
bin->size_taken &= ~1ULL;
bin->next = freelist_tail;
freelist_tail = bin;
start_merge_loop: {
heap_bin_t *prevbin = HEAP_BIN_BEFORE(bin);
heap_bin_t *nextbin = HEAP_BIN_AFTER(bin);
if((uintptr_t)prevbin >= __heap_start) {
if(!HEAP_BIN_TAKEN(prevbin)) {
jove_kprintf("Merge back bin %p into %p\n", bin, prevbin);
freelist_tail = prevbin;
prevbin->size_taken += bin->size_taken + sizeof(heap_bin_t) + sizeof(uintptr_t);
bin = prevbin;
goto start_merge_loop;
}
}
if((uintptr_t)nextbin < __heap_end) {
if(!HEAP_BIN_TAKEN(nextbin)) {
jove_kprintf("Merge forward bin %p into %p\n", bin, nextbin);
if(bin->next == nextbin) bin->next = nextbin->next;
bin->size_taken += nextbin->size_taken + sizeof(heap_bin_t) + sizeof(uintptr_t);
goto start_merge_loop;
}
}
}
}
void
__libc_heap_init(uintptr_t program_end)
{
__heap_start = __heap_end = program_end;
freelist_tail = heap_newbin(__heap_start, LIBC_HEAP_INIT_SIZE, NULL);
}
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