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/*

 * Copyright (c) 2006 Jakub Jermar

 * All rights reserved.

 *

 * Redistribution and use in source and binary forms, with or without

 * modification, are permitted provided that the following conditions

 * are met:

 *

 * - Redistributions of source code must retain the above copyright

 *   notice, this list of conditions and the following disclaimer.

 * - Redistributions in binary form must reproduce the above copyright

 *   notice, this list of conditions and the following disclaimer in the

 *   documentation and/or other materials provided with the distribution.

 * - The name of the author may not be used to endorse or promote products

 *   derived from this software without specific prior written permission.

 *

 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR

 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES

 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.

 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,

 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT

 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,

 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY

 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT

 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF

 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

 */

/** @addtogroup libc

 * @{

 */

/** @file

 */ 

#include <as.h>

#include <libc.h>

#include <unistd.h>

#include <align.h>

#include <sys/types.h>

#include <bitops.h>

/**

 * Either 4*256M on 32-bit architecures or 16*256M on 64-bit architectures.

 */

#define MAX_HEAP_SIZE	(sizeof(uintptr_t)<<28)

/** Create address space area.

 *

 * @param address Virtual address where to place new address space area.

 * @param size Size of the area.

 * @param flags Flags describing type of the area.

 *

 * @return address on success, (void *) -1 otherwise.

 */

void *as_area_create(void *address, size_t size, int flags)

{

	return (void *) __SYSCALL3(SYS_AS_AREA_CREATE, (sysarg_t ) address,

	    (sysarg_t) size, (sysarg_t) flags);

}

/** Resize address space area.

 *

 * @param address Virtual address pointing into already existing address space

 * 	area.

 * @param size New requested size of the area.

 * @param flags Currently unused.

 *

 * @return Zero on success or a code from @ref errno.h on failure.

 */

int as_area_resize(void *address, size_t size, int flags)

{

	return __SYSCALL3(SYS_AS_AREA_RESIZE, (sysarg_t ) address,

	    (sysarg_t) size, (sysarg_t) flags);

}

/** Destroy address space area.

 *

 * @param address Virtual address pointing into the address space area being

 * 	destroyed.

 *

 * @return Zero on success or a code from @ref errno.h on failure.

 */

int as_area_destroy(void *address)

{

	return __SYSCALL1(SYS_AS_AREA_DESTROY, (sysarg_t ) address);

}

/** Change address-space area flags.

 *

 * @param address Virtual address pointing into the address space area being

 * 	modified.

 * @param flags New flags describing type of the area.

 *

 * @return Zero on success or a code from @ref errno.h on failure.

 */

int as_area_change_flags(void *address, int flags)

{

	return __SYSCALL2(SYS_AS_AREA_CHANGE_FLAGS, (sysarg_t) address,

	    (sysarg_t) flags);

}

static size_t heapsize = 0;

static size_t maxheapsize = (size_t) (-1);

static void * last_allocated = 0;

/* Start of heap linker symbol */

extern char _heap;

/** Sbrk emulation 

 *

 * @param incr New area that should be allocated or negative, 

               if it should be shrinked

 * @return Pointer to newly allocated area

 */

void *sbrk(ssize_t incr)

{

	int rc;

	void *res;

	/* Check for invalid values */

	if (incr < 0 && -incr > heapsize)

		return NULL;

	/* Check for too large value */

	if (incr > 0 && incr+heapsize < heapsize)

		return NULL;

	/* Check for too small values */

	if (incr < 0 && incr+heapsize > heapsize)

		return NULL;

	/* Check for user limit */

	if ((maxheapsize != (size_t) (-1)) && (heapsize + incr) > maxheapsize)

		return NULL;

	rc = as_area_resize(&_heap, heapsize + incr, 0);

	if (rc != 0)

		return NULL;

	/* Compute start of new area */

	res = (void *) &_heap + heapsize;

	heapsize += incr;

	return res;

}

/** Set maximum heap size and return pointer just after the heap */

void *set_maxheapsize(size_t mhs)

{

	maxheapsize = mhs;

	/* Return pointer to area not managed by sbrk */

	return ((void *) &_heap + maxheapsize);

}

/** Return pointer to some unmapped area, where fits new as_area

 *

 * @param sz Requested size of the allocation.

 *

 * @return Pointer to the beginning 

 *

 * TODO: make some first_fit/... algorithm, we are now just incrementing

 *       the pointer to last area

 */

void *as_get_mappable_page(size_t sz)

{

	void *res;

	uint64_t asz;

	int i;

	if (!sz)

		return NULL;	

	asz = 1 << (fnzb64(sz - 1) + 1);

	/* Set heapsize to some meaningful value */

	if (maxheapsize == -1)

		set_maxheapsize(MAX_HEAP_SIZE);

	/*

	 * Make sure we allocate from naturally aligned address.

	 */

	i = 0;

	if (!last_allocated) {

		last_allocated = (void *) ALIGN_UP((void *) &_heap +

		    maxheapsize, asz);

	} else {

		last_allocated = (void *) ALIGN_UP(((uintptr_t)

		    last_allocated) + (int) (i > 0), asz);

	}

	res = last_allocated;

	last_allocated += ALIGN_UP(sz, PAGE_SIZE);

	return res;

}

/** @}

 */