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#include <stddef.h>
#ifndef CT_HEAP_ALIGN
#define CT_HEAP_ALIGN 8
#endif
#ifndef CT_HEAP_BASE
#define CT_HEAP_BASE 0x400
#endif
#ifndef CT_HEAP_START
#define CT_HEAP_START 0x444
#endif
#ifndef CT_HEAP_LIMIT
#define CT_HEAP_LIMIT (1 << 24)
#endif
#ifndef CT_HEAP_BLOCKS
#define CT_HEAP_BLOCKS 0x4
#endif
extern void print_s(char *);
extern void print_i(size_t);
extern void print_f(float);
typedef struct CT_Block CT_Block;
struct CT_Block {
void *addr;
CT_Block *next;
size_t size;
};
typedef struct {
CT_Block *free; // first free block
CT_Block *head; // first used block
CT_Block *avail; // first available blank block
size_t top; // top free addr
size_t limit; // heap limit
CT_Block blocks[CT_HEAP_BLOCKS];
} CT_Heap;
CT_Heap foo = {.free = NULL,
.head = NULL,
.top = CT_HEAP_BASE + sizeof(CT_Heap),
.limit = CT_HEAP_LIMIT};
static CT_Heap *heap = (CT_Heap *)CT_HEAP_BASE;
/**
* Insert block into free list, sorted by addr.
*/
static void insert_block(CT_Block *block) {
CT_Block *ptr = heap->free;
CT_Block *prev = NULL;
while (ptr != NULL) {
if ((size_t)block->addr <= (size_t)ptr->addr) {
print_s("insert");
print_i((size_t)ptr);
break;
}
prev = ptr;
ptr = ptr->next;
}
if (prev != NULL) {
if (ptr == NULL) {
print_s("new tail");
}
prev->next = block;
} else {
print_s("new head");
heap->free = block;
}
block->next = ptr;
}
static void release_blocks(CT_Block *scan, CT_Block *to) {
CT_Block *scan_next;
while (scan != to) {
print_s("release");
print_i((size_t)scan);
scan_next = scan->next;
scan->next = heap->avail;
scan->addr = 0;
scan->size = 0;
heap->avail = scan;
scan = scan_next;
}
}
static void compress() {
CT_Block *ptr = heap->free;
CT_Block *prev = NULL;
CT_Block *scan;
while (ptr != NULL) {
prev = ptr;
scan = ptr->next;
size_t base = (size_t)ptr->addr;
while (scan != NULL &&
(size_t)prev->addr + prev->size == (size_t)scan->addr) {
print_s("match");
print_i((size_t)scan);
prev = scan;
scan = scan->next;
}
size_t new_size = prev->addr + prev->size - ptr->addr;
if (new_size > ptr->size) {
print_s("new size");
print_i(new_size);
ptr->size = new_size;
// make merged blocks available
release_blocks(ptr->next, prev);
// relink
ptr->next = prev->next;
ptr = prev;
}
ptr = ptr->next;
}
}
void ct_heap_init() {
heap->free = NULL;
heap->head = NULL;
heap->avail = heap->blocks;
heap->top = CT_HEAP_BASE + sizeof(CT_Heap);
heap->limit = CT_HEAP_LIMIT;
CT_Block *block = heap->blocks;
for (size_t i = CT_HEAP_BLOCKS - 1; i > 0; i--) {
block->next = block + 1;
block++;
}
}
int ct_free(void *free) {
CT_Block *block = heap->head;
CT_Block *prev = NULL;
while (block != NULL) {
if (free == block->addr) {
if (prev) {
prev->next = block->next;
} else {
heap->head = block->next;
}
insert_block(block);
compress();
return 0;
}
prev = block;
block = block->next;
}
return 1;
}
void *ct_malloc(size_t num) {
CT_Block *ptr = heap->free;
CT_Block *prev = NULL;
size_t top = heap->top;
num = (num + CT_HEAP_ALIGN - 1) & -CT_HEAP_ALIGN;
while (ptr != NULL) {
const int is_top = (size_t)ptr->addr + ptr->size >= top;
if (is_top || ptr->size >= num) {
if (prev != NULL) {
prev->next = ptr->next;
} else {
heap->free = ptr->next;
}
ptr->next = heap->head;
heap->head = ptr;
if (is_top) {
ptr->size = num;
heap->top = (size_t)ptr->addr + num;
}
return ptr->addr;
}
prev = ptr;
ptr = ptr->next;
}
// no matching free blocks
// see if any other blocks available
size_t new_top = top + num;
if (heap->avail != NULL && new_top <= heap->limit) {
ptr = heap->avail;
heap->avail = ptr->next;
ptr->addr = (void *)top;
ptr->next = heap->head;
ptr->size = num;
heap->head = ptr;
heap->top = new_top;
return ptr->addr;
}
return NULL;
}
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