alloc.c & alloc.h v1

alloc.c

-#include "alloc.h"
+#include "alloc.h"즈
+#define MSIZE sizeof(meta_struct)-4
+
+void* total = 0;
+void* base = 0;
+void* end = 0;
+void* cur = 0;
+int fit;//0 1 2
+
+meta* search(void* ptr, size_t size){//current pointer
+  mata* index = base;
+  meta* result = 0;
+
+  if(base == ptr)
+    return 0;
+
+  switch(fit){
+    case 0://first fit
+      while(index){ //처음만나는 free가 0이 아닌것에 넣고 탈출
+	if(index->free == 1 && index->size >= size){
+	  result = index;
+	  break;
+	}
+	index = index->next;
+      }
+      break;
+    case 1://best fit
+      while(index){
+	if(index->free == 1 && index->size >= size){
+	  if(result->size > index->size)
+	    result = index; //조건을 충족 시킬때, result보다 작으면update
+	}
+	index = index->next;
+      }
+      break;
+    case 2://worst fit
+      while(index){
+	if(index->free == 1 && index->size >= size){
+	  if(result->size < index->size)
+	    result = index; //조건을 충족 시킬때, result보다 크면update
+	}
+	index = index->next;
+      }
+      break;
+  }return result;
+}
+
+void *m_malloc(size_t size){
+  if(base == 0){
+    end = cur = total = base = sbrk(0); //sbrk 주소반환
+  }
+
+  if((size%4) != 0)
+    size = (size/4+1)*4;
+  
+  meta* target = search(total, size); //find chunk
+
+  if(target == 0){
+    meta* new = total;
+    meta* now = cur;
+
+    sbrk(total + size + MSIZE);
+    now->next = new;
+    new->prev = now;
+    if(total = cur)
+      new->prev = 0;
+    
+    new->next = 0;
+    new->free = 0;
+    new->size = size;
+    cur = new;
+
+    total = total + size + MSIZE;
+    return new->data;
+  }else{
+    m_realloc(target->data, size);
+  }
+  return target->data;
+}
+
+void m_free(void *ptr){
+  meta* target;
+  target = ptr - MSIZE;
+  target->free = 1;
+
+  if(target->prev != NULL){
+    if(target->prev->free == 1){ //이전이 비어있으면 합침
+      target->prev->size = target->prev->size + target->size + MSIZE;
+      target->prev->next = target->next;
+      target->next->prev = target->prev;
+    }
+    if(target->next == NULL) //prev는 있지만 next가 없을때
+      target->prev->next = NULL;
+  }
+  if(target->next != NULL){ //next가 있을때
+    if(target->next->free == 1){ //다음이 비어있으면 합침
+      target->next->size = target->next->size + target->size + MSIZE;
+      target->next->prev = target->prev;
+      target->prev->next = target->next;
+    }
+  }
+}
+
+void* m_realloc(void* ptr, size_t size){
+  meta* old = ptr - MSIZE; //meta 제외 사이
+  
+  if(size%4 != 0){
+    size = (size/4 + 1)*4; //4배수 맞추기
+  }
+  
+  if(old->size == size) return ptr;
+  if(old->next != NULL){
+    if(old->next->free == 1){
+      old->size = old->size + old->next->size + MSIZE;
+      old->next = old->next->next;
+      old->next->prev = old;
+    }
+  }
+  else if(old->size < size){
+    old->free = 1;
+    meta* new = m_malloc(size);
+    memcpy(new, ptr, size);
+    return new;
+  }
+  else if(old->size < size + MSIZE){
+    return ptr;
+  }
+  else{
+    meta* new = old + size + MSIZE;
+    
+    new->free = 1;
+    new->next = old->next;
+    new->prev = old;
+    new->size = old->size - size - MSIZE;
+      
+    old->next = new;
+    old->size = size;
+    old->free = 0;
+
+    m_free(new->data);
+    return old->data;
+  }
+}

alloc.h

@@ -2,7 +2,14 @@
 #define _ALLOC_H_
 
 typedef struct meta_struct {
+  //double linked list
+  struct meta* prev;
+  struct meta* next;
 
+  size_t size;
+  bool free;
+  //char* data; //for string pointer
+  char data[1];
 } meta;
 
 #endif

main.c

 #include "alloc.h"
 
+extern int fit;
+
 int main()
 {
   return 0;