cvsroot/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)
 */

#define _GNU_SOURCE 1

#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 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* 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;
}

void* 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);
}

void* 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:	1.1
Committed:	Sat Nov 28 05:57:08 2015 UTC (8 years, 7 months ago) by root
Content type:	text/plain
Branch:	MAIN
Log Message:	* empty log message *
#	User	Rev	Content
1	root	1.1	/*
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			#define _GNU_SOURCE 1
11
12			#include <unistd.h>
13			#include <sys/mman.h>
14			#include <errno.h>
15
16			#include <sys/types.h>
17			#include <stddef.h>
18			#include <stdlib.h>
19			#include <string.h>
20
21			#include <limits.h>
22			//#include <sys/shm.h> /* for PAGE_SIZE */
23
24			#ifndef PAGE_SIZE
25			#define PAGE_SIZE sysconf (_SC_PAGESIZE)
26			#endif
27
28			#ifndef MREMAP_MAYMOVE
29			#define MREMAP_MAYMOVE 1
30			#endif
31
32			/* -- HELPER CODE --------------------------------------------------------- */
33
34			#ifndef MAP_FAILED
35			#define MAP_FAILED ((void*)-1)
36			#endif
37
38			#ifndef NULL
39			#define NULL ((void*)0)
40			#endif
41
42			typedef struct {
43			void* next;
44			size_t size;
45			} __alloc_t;
46
47			#define BLOCK_START(b) (((void*)(b))-sizeof(__alloc_t))
48			#define BLOCK_RET(b) (((void*)(b))+sizeof(__alloc_t))
49
50			#define MEM_BLOCK_SIZE PAGE_SIZE
51			#define PAGE_ALIGN(s) (((s)+MEM_BLOCK_SIZE-1)&(unsigned long)(~(MEM_BLOCK_SIZE-1)))
52
53			/* a simple mmap :) */
54			#if defined(__i386__)
55			#define REGPARM(x) __attribute__((regparm(x)))
56			#else
57			#define REGPARM(x)
58			#endif
59
60			static void REGPARM(1) *do_mmap(size_t size) {
61			return mmap(0, size, PROT_READ\|PROT_WRITE, MAP_ANONYMOUS\|MAP_PRIVATE, -1, (size_t)0);
62			}
63
64			/* -- SMALL MEM ----------------------------------------------------------- */
65
66			static __alloc_t* __small_mem[8];
67
68			#define __SMALL_NR(i) (MEM_BLOCK_SIZE/(i))
69
70			#define __MIN_SMALL_SIZE __SMALL_NR(256) /* 16 / 32 */
71			#define __MAX_SMALL_SIZE __SMALL_NR(2) /* 2048 / 4096 */
72
73			#define GET_SIZE(s) (__MIN_SMALL_SIZE<<get_index((s)))
74
75			#define FIRST_SMALL(p) (((unsigned long)(p))&(~(MEM_BLOCK_SIZE-1)))
76
77			static inline int __ind_shift() { return (MEM_BLOCK_SIZE==4096)?4:5; }
78
79			static size_t REGPARM(1) get_index(size_t _size) {
80			register size_t idx=0;
81			// if (_size) { /* we already check this in the callers */
82			register size_t size=((_size-1)&(MEM_BLOCK_SIZE-1))>>__ind_shift();
83			while(size) { size>>=1; ++idx; }
84			// }
85			return idx;
86			}
87
88			/* small mem */
89			static void __small_free(void*_ptr,size_t _size) REGPARM(2);
90
91			static void REGPARM(2) __small_free(void*_ptr,size_t _size) {
92			__alloc_t* ptr=BLOCK_START(_ptr);
93			size_t size=_size;
94			size_t idx=get_index(size);
95
96			#ifdef WANT_FREE_OVERWRITE
97			memset(ptr,0x55,size); /* allways zero out small mem */
98			#else
99			#if 0
100			memset(ptr,0,size); /* allways zero out small mem */
101			#endif
102			#endif
103
104			ptr->next=__small_mem[idx];
105			__small_mem[idx]=ptr;
106			}
107
108			static void* REGPARM(1) __small_malloc(size_t _size) {
109			__alloc_t *ptr;
110			size_t size=_size;
111			size_t idx;
112
113			idx=get_index(size);
114			ptr=__small_mem[idx];
115
116			if (ptr==0) { /* no free blocks ? */
117			register int i,nr;
118			ptr=do_mmap(MEM_BLOCK_SIZE);
119			if (ptr==MAP_FAILED) return MAP_FAILED;
120
121			__small_mem[idx]=ptr;
122
123			nr=__SMALL_NR(size)-1;
124			for (i=0;i<nr;i++) {
125			ptr->next=(((void*)ptr)+size);
126			ptr=ptr->next;
127			}
128			ptr->next=0;
129
130			ptr=__small_mem[idx];
131			}
132
133			/* get a free block */
134			__small_mem[idx]=ptr->next;
135			ptr->next=0;
136
137			return ptr;
138			}
139
140			/* -- PUBLIC FUNCTIONS ---------------------------------------------------- */
141
142			void free(void *ptr) {
143			register size_t size;
144			if (ptr) {
145			size=((__alloc_t*)BLOCK_START(ptr))->size;
146			if (size) {
147			if (size<=__MAX_SMALL_SIZE)
148			__small_free(ptr,size);
149			else
150			munmap(BLOCK_START(ptr),size);
151			}
152			}
153			}
154
155			void* malloc(size_t size) {
156			__alloc_t* ptr;
157			size_t need;
158			if (!size) goto err_out;
159			size+=sizeof(__alloc_t);
160			if (size<sizeof(__alloc_t)) goto err_out;
161			if (size<=__MAX_SMALL_SIZE) {
162			need=GET_SIZE(size);
163			ptr=__small_malloc(need);
164			}
165			else {
166			need=PAGE_ALIGN(size);
167			if (!need) ptr=MAP_FAILED; else ptr=do_mmap(need);
168			}
169			if (ptr==MAP_FAILED) goto err_out;
170			ptr->size=need;
171			return BLOCK_RET(ptr);
172			err_out:
173			//(*__errno_location())=ENOMEM;
174			return 0;
175			}
176
177			void* calloc(size_t nmemb, size_t _size) {
178			register size_t size=_size*nmemb;
179			if (nmemb && size/nmemb!=_size) {
180			//(*__errno_location())=ENOMEM;
181			return 0;
182			}
183			#ifdef WANT_FREE_OVERWRITE
184			if (size<__MAX_SMALL_SIZE) {
185			void* x=malloc(size);
186			memset(x,0,size);
187			return x;
188			} else
189			#endif
190			return malloc(size);
191			}
192
193			void* 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