summaryrefslogblamecommitdiff
path: root/src/malloc/lite_malloc.c
blob: a7e4a9f7b511bdbf2db4d5018e5088c19ed38570 (plain) (tree)
1
2
3
4
5
6
7
8
9
10





                   

                

                              
                                      
 
                               
                                    

                            
 
                    

                                      
 
                   
 

















                                              
 

                      
                     
                 


                                    
                                       
#include <stdlib.h>
#include <stdint.h>
#include <limits.h>
#include <errno.h>
#include "libc.h"

#define ALIGN 16

void *__expand_heap(size_t *);

static void *__simple_malloc(size_t n)
{
	static char *cur, *end;
	static volatile int lock[2];
	size_t align=1, pad;
	void *p;

	if (!n) n++;
	while (align<n && align<ALIGN)
		align += align;

	LOCK(lock);

	pad = -(uintptr_t)cur & align-1;

	if (n <= SIZE_MAX/2 + ALIGN) n += pad;

	if (n > end-cur) {
		size_t m = n;
		char *new = __expand_heap(&m);
		if (!new) {
			UNLOCK(lock);
			return 0;
		}
		if (new != end) {
			cur = new;
			n -= pad;
			pad = 0;
		}
		end = new + m;
	}

	p = cur + pad;
	cur += n;
	UNLOCK(lock);
	return p;
}

weak_alias(__simple_malloc, malloc);
weak_alias(__simple_malloc, __malloc0);