microscheme/malloc.c

/*
 * malloc/free by O.Dreesen
 *
 * first TRY:
 *   lists w/magics
 * and now the second TRY
 *   let the kernel map all the stuff (if there is something to do)
 */

#include <unistd.h>
#include <sys/mman.h>
#include <errno.h>

#include <sys/types.h>
#include <stddef.h>
#include <stdlib.h>
#include <string.h>

#include <limits.h>
//#include <sys/shm.h>  /* for PAGE_SIZE */

#ifndef PAGE_SIZE
 #define PAGE_SIZE sysconf (_SC_PAGESIZE)
#endif

#ifndef MREMAP_MAYMOVE
 #define MREMAP_MAYMOVE 1
#endif

/* -- HELPER CODE --------------------------------------------------------- */

#ifndef MAP_FAILED
#define MAP_FAILED ((void*)-1)
#endif

#ifndef NULL
#define NULL ((void*)0)
#endif

typedef struct {
  void*  next;
  size_t size;
} alloc_t;

#define BLOCK_START(b)  (((void*)(b))-sizeof(alloc_t))
#define BLOCK_RET(b)    (((void*)(b))+sizeof(alloc_t))

#define MEM_BLOCK_SIZE  PAGE_SIZE
#define PAGE_ALIGN(s)   (((s)+MEM_BLOCK_SIZE-1)&(unsigned long)(~(MEM_BLOCK_SIZE-1)))

/* a simple mmap :) */
#if defined(i386)
#define REGPARM(x) attribute((regparm(x)))
#else
#define REGPARM(x)
#endif

static void REGPARM(1) *do_mmap(size_t size) {
  return mmap(0, size, PROT_READ|PROT_WRITE, MAP_ANONYMOUS|MAP_PRIVATE, -1, (size_t)0);
}

/* -- SMALL MEM ----------------------------------------------------------- */

static alloc_t* small_mem[8];

#define SMALL_NR(i)             (MEM_BLOCK_SIZE/(i))

#define MIN_SMALL_SIZE  SMALL_NR(256)           /*   16 /   32 */
#define MAX_SMALL_SIZE  SMALL_NR(2)             /* 2048 / 4096 */

#define GET_SIZE(s)             (MIN_SMALL_SIZE<<get_index((s)))

#define FIRST_SMALL(p)          (((unsigned long)(p))&(~(MEM_BLOCK_SIZE-1)))

static inline int ind_shift() { return (MEM_BLOCK_SIZE==4096)?4:5; }

static size_t REGPARM(1) get_index(size_t _size) {
  register size_t idx=0;
//  if (_size) {        /* we already check this in the callers */
    register size_t size=((_size-1)&(MEM_BLOCK_SIZE-1))>>ind_shift();
    while(size) { size>>=1; ++idx; }
//  }
  return idx;
}

/* small mem */
static void small_free(void*_ptr,size_t _size) REGPARM(2);

static void REGPARM(2) small_free(void*_ptr,size_t _size) {
  alloc_t* ptr=BLOCK_START(_ptr);
  size_t size=_size;
  size_t idx=get_index(size);

#ifdef WANT_FREE_OVERWRITE
  memset(ptr,0x55,size);        /* allways zero out small mem */
#else
#if 0
  memset(ptr,0,size);   /* allways zero out small mem */
#endif
#endif

  ptr->next=small_mem[idx];
  small_mem[idx]=ptr;
}

static void* REGPARM(1) small_malloc(size_t _size) {
  alloc_t *ptr;
  size_t size=_size;
  size_t idx;

  idx=get_index(size);
  ptr=small_mem[idx];

  if (ptr==0)  {        /* no free blocks ? */
    register int i,nr;
    ptr=do_mmap(MEM_BLOCK_SIZE);
    if (ptr==MAP_FAILED) return MAP_FAILED;

    small_mem[idx]=ptr;

    nr=SMALL_NR(size)-1;
    for (i=0;i<nr;i++) {
      ptr->next=(((void*)ptr)+size);
      ptr=ptr->next;
    }
    ptr->next=0;

    ptr=small_mem[idx];
  }

  /* get a free block */
  small_mem[idx]=ptr->next;
  ptr->next=0;

  return ptr;
}

/* -- PUBLIC FUNCTIONS ---------------------------------------------------- */

void tiny_free(void *ptr) {
  register size_t size;
  if (ptr) {
    size=((alloc_t*)BLOCK_START(ptr))->size;
    if (size) {
      if (size<=MAX_SMALL_SIZE)
        small_free(ptr,size);
      else
        munmap(BLOCK_START(ptr),size);
    }
  }
}

void* tiny_malloc(size_t size) {
  alloc_t* ptr;
  size_t need;
  if (!size) goto err_out;
  size+=sizeof(alloc_t);
  if (size<sizeof(alloc_t)) goto err_out;
  if (size<=MAX_SMALL_SIZE) {
    need=GET_SIZE(size);
    ptr=small_malloc(need);
  }
  else {
    need=PAGE_ALIGN(size);
    if (!need) ptr=MAP_FAILED; else ptr=do_mmap(need);
  }
  if (ptr==MAP_FAILED) goto err_out;
  ptr->size=need;
  return BLOCK_RET(ptr);
err_out:
  //(*errno_location())=ENOMEM;
  return 0;
}

#if 0
void* tiny_calloc(size_t nmemb, size_t _size) {
  register size_t size=_size*nmemb;
  if (nmemb && size/nmemb!=_size) {
    //(*errno_location())=ENOMEM;
    return 0;
  }
#ifdef WANT_FREE_OVERWRITE
  if (size<MAX_SMALL_SIZE) {
    void* x=malloc(size);
    memset(x,0,size);
    return x;
  } else
#endif
  return malloc(size);
}
#endif

void* tiny_realloc(void* ptr, size_t _size) {
  register size_t size=_size;
  if (ptr) {
    if (size) {
      alloc_t* tmp=BLOCK_START(ptr);
      size+=sizeof(alloc_t);
      if (size<sizeof(alloc_t)) goto retzero;
      size=(size<=MAX_SMALL_SIZE)?GET_SIZE(size):PAGE_ALIGN(size);
      if (tmp->size!=size) {
        if ((tmp->size<=MAX_SMALL_SIZE)) {
          void *new=malloc(_size);
          if (new) {
            register alloc_t* foo=BLOCK_START(new);
            size=foo->size;
            if (size>tmp->size) size=tmp->size;
            if (size) memcpy(new,ptr,size-sizeof(alloc_t));
            free(ptr);
          }
          ptr=new;
        }
        else {
          register alloc_t* foo;
          size=PAGE_ALIGN(size);
          foo=mremap(tmp,tmp->size,size,MREMAP_MAYMOVE);
          if (foo==MAP_FAILED) {
retzero:
            //(*errno_location())=ENOMEM;
            ptr=0;
          }
          else {
            foo->size=size;
            ptr=BLOCK_RET(foo);
          }
        }
      }
    }
    else { /* size==0 */
      free(ptr);
      ptr = NULL;
    }
  }
  else { /* ptr==0 */
    if (size) {
      ptr=malloc(size);
    }
  }
  return ptr;
}

Revision:	1.2
Committed:	Wed Dec 2 07:43:46 2015 UTC (10 years, 9 months ago) by root
Content type:	text/plain
Branch:	MAIN
CVS Tags:	HEAD
Changes since 1.1:	+50 -50 lines
Log Message:	* empty log message *
#	Content
1	/*
2	* malloc/free by O.Dreesen
3	*
4	* first TRY:
5	* lists w/magics
6	* and now the second TRY
7	* let the kernel map all the stuff (if there is something to do)
8	*/
9
10	#include <unistd.h>
11	#include <sys/mman.h>
12	#include <errno.h>
13
14	#include <sys/types.h>
15	#include <stddef.h>
16	#include <stdlib.h>
17	#include <string.h>
18
19	#include <limits.h>
20	//#include <sys/shm.h> /* for PAGE_SIZE */
21
22	#ifndef PAGE_SIZE
23	#define PAGE_SIZE sysconf (_SC_PAGESIZE)
24	#endif
25
26	#ifndef MREMAP_MAYMOVE
27	#define MREMAP_MAYMOVE 1
28	#endif
29
30	/* -- HELPER CODE --------------------------------------------------------- */
31
32	#ifndef MAP_FAILED
33	#define MAP_FAILED ((void*)-1)
34	#endif
35
36	#ifndef NULL
37	#define NULL ((void*)0)
38	#endif
39
40	typedef struct {
41	void* next;
42	size_t size;
43	} alloc_t;
44
45	#define BLOCK_START(b) (((void*)(b))-sizeof(alloc_t))
46	#define BLOCK_RET(b) (((void*)(b))+sizeof(alloc_t))
47
48	#define MEM_BLOCK_SIZE PAGE_SIZE
49	#define PAGE_ALIGN(s) (((s)+MEM_BLOCK_SIZE-1)&(unsigned long)(~(MEM_BLOCK_SIZE-1)))
50
51	/* a simple mmap :) */
52	#if defined(i386)
53	#define REGPARM(x) attribute((regparm(x)))
54	#else
55	#define REGPARM(x)
56	#endif
57
58	static void REGPARM(1) *do_mmap(size_t size) {
59	return mmap(0, size, PROT_READ\|PROT_WRITE, MAP_ANONYMOUS\|MAP_PRIVATE, -1, (size_t)0);
60	}
61
62	/* -- SMALL MEM ----------------------------------------------------------- */
63
64	static alloc_t* small_mem[8];
65
66	#define SMALL_NR(i) (MEM_BLOCK_SIZE/(i))
67
68	#define MIN_SMALL_SIZE SMALL_NR(256) /* 16 / 32 */
69	#define MAX_SMALL_SIZE SMALL_NR(2) /* 2048 / 4096 */
70
71	#define GET_SIZE(s) (MIN_SMALL_SIZE<<get_index((s)))
72
73	#define FIRST_SMALL(p) (((unsigned long)(p))&(~(MEM_BLOCK_SIZE-1)))
74
75	static inline int ind_shift() { return (MEM_BLOCK_SIZE==4096)?4:5; }
76
77	static size_t REGPARM(1) get_index(size_t _size) {
78	register size_t idx=0;
79	// if (_size) { /* we already check this in the callers */
80	register size_t size=((_size-1)&(MEM_BLOCK_SIZE-1))>>ind_shift();
81	while(size) { size>>=1; ++idx; }
82	// }
83	return idx;
84	}
85
86	/* small mem */
87	static void small_free(void*_ptr,size_t _size) REGPARM(2);
88
89	static void REGPARM(2) small_free(void*_ptr,size_t _size) {
90	alloc_t* ptr=BLOCK_START(_ptr);
91	size_t size=_size;
92	size_t idx=get_index(size);
93
94	#ifdef WANT_FREE_OVERWRITE
95	memset(ptr,0x55,size); /* allways zero out small mem */
96	#else
97	#if 0
98	memset(ptr,0,size); /* allways zero out small mem */
99	#endif
100	#endif
101
102	ptr->next=small_mem[idx];
103	small_mem[idx]=ptr;
104	}
105
106	static void* REGPARM(1) small_malloc(size_t _size) {
107	alloc_t *ptr;
108	size_t size=_size;
109	size_t idx;
110
111	idx=get_index(size);
112	ptr=small_mem[idx];
113
114	if (ptr==0) { /* no free blocks ? */
115	register int i,nr;
116	ptr=do_mmap(MEM_BLOCK_SIZE);
117	if (ptr==MAP_FAILED) return MAP_FAILED;
118
119	small_mem[idx]=ptr;
120
121	nr=SMALL_NR(size)-1;
122	for (i=0;i<nr;i++) {
123	ptr->next=(((void*)ptr)+size);
124	ptr=ptr->next;
125	}
126	ptr->next=0;
127
128	ptr=small_mem[idx];
129	}
130
131	/* get a free block */
132	small_mem[idx]=ptr->next;
133	ptr->next=0;
134
135	return ptr;
136	}
137
138	/* -- PUBLIC FUNCTIONS ---------------------------------------------------- */
139
140	void tiny_free(void *ptr) {
141	register size_t size;
142	if (ptr) {
143	size=((alloc_t*)BLOCK_START(ptr))->size;
144	if (size) {
145	if (size<=MAX_SMALL_SIZE)
146	small_free(ptr,size);
147	else
148	munmap(BLOCK_START(ptr),size);
149	}
150	}
151	}
152
153	void* tiny_malloc(size_t size) {
154	alloc_t* ptr;
155	size_t need;
156	if (!size) goto err_out;
157	size+=sizeof(alloc_t);
158	if (size<sizeof(alloc_t)) goto err_out;
159	if (size<=MAX_SMALL_SIZE) {
160	need=GET_SIZE(size);
161	ptr=small_malloc(need);
162	}
163	else {
164	need=PAGE_ALIGN(size);
165	if (!need) ptr=MAP_FAILED; else ptr=do_mmap(need);
166	}
167	if (ptr==MAP_FAILED) goto err_out;
168	ptr->size=need;
169	return BLOCK_RET(ptr);
170	err_out:
171	//(*errno_location())=ENOMEM;
172	return 0;
173	}
174
175	#if 0
176	void* tiny_calloc(size_t nmemb, size_t _size) {
177	register size_t size=_size*nmemb;
178	if (nmemb && size/nmemb!=_size) {
179	//(*errno_location())=ENOMEM;
180	return 0;
181	}
182	#ifdef WANT_FREE_OVERWRITE
183	if (size<MAX_SMALL_SIZE) {
184	void* x=malloc(size);
185	memset(x,0,size);
186	return x;
187	} else
188	#endif
189	return malloc(size);
190	}
191	#endif
192
193	void* tiny_realloc(void* ptr, size_t _size) {
194	register size_t size=_size;
195	if (ptr) {
196	if (size) {
197	alloc_t* tmp=BLOCK_START(ptr);
198	size+=sizeof(alloc_t);
199	if (size<sizeof(alloc_t)) goto retzero;
200	size=(size<=MAX_SMALL_SIZE)?GET_SIZE(size):PAGE_ALIGN(size);
201	if (tmp->size!=size) {
202	if ((tmp->size<=MAX_SMALL_SIZE)) {
203	void *new=malloc(_size);
204	if (new) {
205	register alloc_t* foo=BLOCK_START(new);
206	size=foo->size;
207	if (size>tmp->size) size=tmp->size;
208	if (size) memcpy(new,ptr,size-sizeof(alloc_t));
209	free(ptr);
210	}
211	ptr=new;
212	}
213	else {
214	register alloc_t* foo;
215	size=PAGE_ALIGN(size);
216	foo=mremap(tmp,tmp->size,size,MREMAP_MAYMOVE);
217	if (foo==MAP_FAILED) {
218	retzero:
219	//(*errno_location())=ENOMEM;
220	ptr=0;
221	}
222	else {
223	foo->size=size;
224	ptr=BLOCK_RET(foo);
225	}
226	}
227	}
228	}
229	else { /* size==0 */
230	free(ptr);
231	ptr = NULL;
232	}
233	}
234	else { /* ptr==0 */
235	if (size) {
236	ptr=malloc(size);
237	}
238	}
239	return ptr;
240	}
241