include/nucleus/heap.h

/*
 * @note Copyright (C) 2001,2002,2003 Philippe Gerum <rpm@xenomai.org>.
 *
 * Xenomai is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published
 * by the Free Software Foundation; either version 2 of the License,
 * or (at your option) any later version.
 *
 * Xenomai is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with Xenomai; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
 * 02111-1307, USA.
 *
 * \ingroup heap
 */

#ifndef _XENO_NUCLEUS_HEAP_H
#define _XENO_NUCLEUS_HEAP_H

#include <nucleus/queue.h>

/*
 * CONSTRAINTS:
 *
 * Minimum page size is 2 ** XNHEAP_MINLOG2 (must be large enough to
 * hold a pointer).
 *
 * Maximum page size is 2 ** XNHEAP_MAXLOG2.
 *
 * Minimum block size equals the minimum page size.
 *
 * Requested block size smaller than the minimum block size is
 * rounded to the minimum block size.
 *
 * Requested block size larger than 2 times the page size is rounded
 * to the next page boundary and obtained from the free page
 * list. So we need a bucket for each power of two between
 * XNHEAP_MINLOG2 and XNHEAP_MAXLOG2 inclusive, plus one to honor
 * requests ranging from the maximum page size to twice this size.
 */

#if defined(__KERNEL__) || defined(__XENO_SIM__)

#define XNHEAP_MINLOG2    3
#define XNHEAP_MAXLOG2    22    /* Must hold pagemap::bcount objects */
#define XNHEAP_MINALLOCSZ (1 << XNHEAP_MINLOG2)
#define XNHEAP_MINALIGNSZ (1 << 4) /* i.e. 16 bytes */
#define XNHEAP_NBUCKETS   (XNHEAP_MAXLOG2 - XNHEAP_MINLOG2 + 2)
#define XNHEAP_MAXEXTSZ   (1 << 31) /* i.e. 2Gb */

#define XNHEAP_PFREE   0
#define XNHEAP_PCONT   1
#define XNHEAP_PLIST   2

typedef struct xnextent {

        xnholder_t link;

#define link2extent(ln) container_of(ln, xnextent_t, link)

        caddr_t membase,        /* Base address of the page array */
                memlim,         /* Memory limit of page array */
                freelist;       /* Head of the free page list */

        struct xnpagemap {      /* Beginning of page map */
                unsigned int type : 8;    /* PFREE, PCONT, PLIST or log2 */
                unsigned int bcount : 24; /* Number of active blocks. */
        } pagemap[1];

} xnextent_t;

typedef struct xnheap {

        xnholder_t link;

#define link2heap(ln)           container_of(ln, xnheap_t, link)

        u_long extentsize,
                pagesize,
                pageshift,
                hdrsize,
                npages,         /* Number of pages per extent */
                ubytes,
                maxcont;

        xnqueue_t extents;

        DECLARE_XNLOCK(lock);

        struct xnbucket {
                caddr_t freelist;
                int fcount;
        } buckets[XNHEAP_NBUCKETS];

        xnholder_t *idleq;

        xnarch_heapcb_t archdep;

        XNARCH_DECL_DISPLAY_CONTEXT();

} xnheap_t;

extern xnheap_t kheap;

#if CONFIG_XENO_OPT_SYS_STACKPOOLSZ > 0
extern xnheap_t kstacks;
#endif

#define xnheap_extentsize(heap)         ((heap)->extentsize)
#define xnheap_page_size(heap)          ((heap)->pagesize)
#define xnheap_page_count(heap)         ((heap)->npages)
#define xnheap_usable_mem(heap)         ((heap)->maxcont * countq(&(heap)->extents))
#define xnheap_used_mem(heap)           ((heap)->ubytes)
#define xnheap_max_contiguous(heap)     ((heap)->maxcont)

static inline size_t xnheap_align(size_t size, size_t al)
{
        /* The alignment value must be a power of 2 */
        return ((size+al-1)&(~(al-1)));
}

static inline size_t xnheap_overhead(size_t hsize, size_t psize)
{
        size_t m = psize / sizeof(struct xnpagemap);
        size_t q = (size_t)xnarch_llimd(hsize - sizeof(xnextent_t), m, m + 1);
        return xnheap_align(hsize - q, XNHEAP_MINALIGNSZ);
}

#define xnmalloc(size)     xnheap_alloc(&kheap,size)
#define xnfree(ptr)        xnheap_free(&kheap,ptr)
#define xnfreesync()       xnheap_finalize_free(&kheap)
#define xnfreesafe(thread,ptr,ln)               \
    do {                                        \
    if (xnpod_current_p(thread))                \
        xnheap_schedule_free(&kheap,ptr,ln);    \
    else                                        \
        xnheap_free(&kheap,ptr);                \
} while(0)

static inline size_t xnheap_rounded_size(size_t hsize, size_t psize)
{
        /*
         * Account for the minimum heap size (i.e. 2 * page size) plus
         * overhead so that the actual heap space is large enough to
         * match the requested size. Using a small page size for large
         * single-block heaps might reserve a lot of useless page map
         * memory, but this should never get pathological anyway,
         * since we only consume 4 bytes per page.
         */
        if (hsize < 2 * psize)
                hsize = 2 * psize;
        hsize += xnheap_overhead(hsize, psize);
        return xnheap_align(hsize, psize);
}

#ifdef __cplusplus
extern "C" {
#endif

/* Private interface. */

#ifdef __KERNEL__

#define XNHEAP_DEV_MINOR 254

int xnheap_mount(void);

void xnheap_umount(void);

int xnheap_init_mapped(xnheap_t *heap,
                       u_long heapsize,
                       int memflags);

int xnheap_destroy_mapped(xnheap_t *heap);

#define xnheap_mapped_offset(heap,ptr) \
(((caddr_t)(ptr)) - ((caddr_t)(heap)->archdep.heapbase))

#define xnheap_mapped_address(heap,off) \
(((caddr_t)(heap)->archdep.heapbase) + (off))

#define xnheap_mapped_p(heap) \
((heap)->archdep.heapbase != NULL)

#endif /* __KERNEL__ */

/* Public interface. */

int xnheap_init(xnheap_t *heap,
                void *heapaddr,
                u_long heapsize,
                u_long pagesize);

int xnheap_destroy(xnheap_t *heap,
                   void (*flushfn)(xnheap_t *heap,
                                   void *extaddr,
                                   u_long extsize,
                                   void *cookie),
                   void *cookie);

int xnheap_extend(xnheap_t *heap,
                  void *extaddr,
                  u_long extsize);

void *xnheap_alloc(xnheap_t *heap,
                   u_long size);

int xnheap_test_and_free(xnheap_t *heap,
                         void *block,
                         int (*ckfn)(void *block));

int xnheap_free(xnheap_t *heap,
                void *block);

void xnheap_schedule_free(xnheap_t *heap,
                          void *block,
                          xnholder_t *link);

void xnheap_finalize_free_inner(xnheap_t *heap);

static inline void xnheap_finalize_free(xnheap_t *heap)
{
    if (heap->idleq)
        xnheap_finalize_free_inner(heap);
}

int xnheap_check_block(xnheap_t *heap,
                       void *block);

#ifdef __cplusplus
}
#endif

#endif /* __KERNEL__ || __XENO_SIM__ */

#define XNHEAP_DEV_NAME  "/dev/rtheap"

#endif /* !_XENO_NUCLEUS_HEAP_H */

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