/*****************************************************************************/

/*  dalist: a zero-dependency book-keeping library                           */

/*  Copyright (C) 2013--2021  SysDeer Technologies, LLC                      */

/*  Released under GPLv2 and GPLv3; see COPYING.DALIST.                      */

/*****************************************************************************/

#include <dalist/dalist.h>

#include "dalist_impl.h"

/* private prototypes */

static void * dalist_alloc(struct dalist_ex * dlist);

static int dalist_memfn_internal(

	struct dalist_ex *	dlist,

	void **			addr,

	size_t *		alloc_size);

dalist_api

int dalist_get_free_node(

	struct dalist_ex *	dlist,

	void **			fnode)

{

	int			ret;

	struct dalist_node *	nfree;

	/* in case we fail */

	*fnode = (void *)0;

	if (dlist->free)

		/* allocation is not needed */

		nfree  = (struct dalist_node *)dlist->free;

	else

		nfree = (struct dalist_node *)dalist_alloc(dlist);

	if (nfree) {

		*fnode = nfree;

		dlist->free = nfree->next;

		if (nfree->next) /* new head of dlist->free */

			nfree->next->prev = 0;

		/* bookkeeping */

		dlist->info.free_nodes--;

		/* and for good measure */

		nfree->prev = nfree->next = 0;

		ret = DALIST_OK;

	} else

		ret = DALIST_EMEMFN;

	return ret;

}

dalist_api

int dalist_deposit_free_node(

	struct dalist_ex *	dlist,

	void *			fnode)

{

	int			ret;

	struct dalist_node *	nfree;

	if (fnode) {

		nfree       = (struct dalist_node *)fnode;

		nfree->next = (struct dalist_node *)dlist->free;

		/* fnode is now the head free node */

		nfree->prev = 0;

		dlist->free = fnode;

		/* bookkeeping */

		dlist->info.free_nodes++;

		ret = DALIST_OK;

	} else {

		ret = DALIST_ENODE;

	}

	return ret;

}

dalist_api

int dalist_deposit_memory_block(

	struct dalist_ex *	dlist,

	void *			addr,

	size_t			alloc_size)

{

	struct dalist_node *	fnode;

	struct dalist_node *	fnode_next;

	char *			naddr;

	char *			naddr_next;

	char *			naddr_upper;

	size_t			node_size;

	/* node_size: before alignment */

	if (dlist->dblock_size == 0)

		node_size = sizeof(struct dalist_node);

	else

		node_size = (size_t)&((struct dalist_node_ex *)0)->dblock

				+ dlist->dblock_size;

	/* node_size: after alignment */

	node_size += sizeof(uintptr_t)-1;

	node_size |= sizeof(uintptr_t)-1;

	node_size ^= sizeof(uintptr_t)-1;

	/* validate block size */

	if (alloc_size < node_size)

		return DALIST_EMEMBLOCK;

	/* marks */

	naddr       = (char *)addr;

	naddr_next  = naddr + node_size;

	naddr_upper = naddr + alloc_size;

	/* chain of free nodes */

	while ((naddr_next + node_size) <= naddr_upper) {

		fnode      = (struct dalist_node *)naddr;

		fnode_next = (struct dalist_node *)naddr_next;

		fnode->next      = fnode_next;

		fnode_next->prev = fnode;

		naddr      += node_size;

		naddr_next += node_size;

	}

	/* free nodes block: head and tail */

	fnode       = (struct dalist_node *)addr;

	fnode_next  = (struct dalist_node *)naddr;

	if (dlist->free) {

		/* link with pre-allocated free nodes */

		fnode_next->next = (struct dalist_node *)dlist->free;

		((struct dalist_node *)dlist->free)->prev = fnode_next;

	} else {

		/* no pre-allocated free nodes */

		fnode_next->next = 0;

	}

	/* fnode is now the head free node */

	fnode->prev = 0;

	dlist->free = fnode;

	/* bookkeeping */

	dlist->info.free_nodes += (alloc_size / node_size);

	return DALIST_OK;

}

static void * __cdecl dalist_alloc(struct dalist_ex * dlist)

{

	int			ret;

	void *			addr;

	size_t			alloc_size;

	memfn_custom *		pmemfn;

	struct dalist_node *	fnode;

	/* pmemfn */

	if (dlist->memfn_method == DALIST_MEMFN_CUSTOM)

		pmemfn = (dalist_memfn_custom *)(uintptr_t)dlist->memfn_ptr;

	else

		pmemfn = dalist_memfn_internal;

	/* allocate: try */

	addr  = 0;

	fnode = 0;

	ret   = pmemfn(dlist,&addr,&alloc_size);

	/* allocate: verify */

	if (ret == DALIST_OK) {

		if (dlist->memfn_method == DALIST_MEMFN_MALLOC)

			fnode = (struct dalist_node *)addr;

		else if (dalist_deposit_memory_block(

				dlist,

				addr,

				alloc_size) == DALIST_OK)

			fnode = (struct dalist_node *)dlist->free;

	}

	return fnode;

}

static int __cdecl dalist_memfn_internal(

	struct dalist_ex *	dlist,

	void **			address,

	size_t *		alloc_size)

{

	int		ret;

	void *		addr;

	size_t		size;

	memfn_mmap *	pfn_mmap;

	memfn_malloc *	pfn_malloc;

	memfn_allocvm * pfn_allocvm;

	switch (dlist->memfn_method) {

		case DALIST_MEMFN_MALLOC:

			if (dlist->dblock_size == 0)

				size = sizeof(struct dalist_node);

			else

				size = (size_t)((struct dalist_node_ex *)0)->dblock

					+ dlist->dblock_size;

			pfn_malloc = (memfn_malloc *)(uintptr_t)dlist->memfn_ptr;

			addr = pfn_malloc(size);

			if (addr) {

				*address = addr;

				*alloc_size = size;

				ret = dlist->memfn_status = DALIST_OK;

			} else {

				ret = DALIST_EMEMFN;

				dlist->memfn_status = dalist_errno(ret);

			}

			break;

		case DALIST_MEMFN_MMAP:

			pfn_mmap = (memfn_mmap * )(uintptr_t)dlist->memfn_ptr;

			addr = pfn_mmap(

				(void *)0,

				dlist->lblock_size,

				PROT_READ | PROT_WRITE,

				MAP_ANON | MAP_SHARED,

				0,0);

			if (addr) {

				*address = addr;

				*alloc_size = dlist->lblock_size;

				ret = dlist->memfn_status = DALIST_OK;

			} else {

				ret = DALIST_EMEMFN;

				dlist->memfn_status = dalist_errno(ret);

			}

			break;

		case DALIST_MEMFN_NT_ALLOCATE_VIRTUAL_MEMORY:

			addr       = (void *)0;

			size = dlist->lblock_size;

			pfn_allocvm = (memfn_allocvm *)(uintptr_t)dlist->memfn_ptr;

			dlist->memfn_status = pfn_allocvm(

				NT_CURRENT_PROCESS_HANDLE,

				&addr,

				0,

				&size,

				NT_MEM_COMMIT,

				NT_PAGE_READWRITE);

			if (dlist->memfn_status == NT_STATUS_SUCCESS) {

				*address = addr;

				*alloc_size = size;

				ret = DALIST_OK;

			} else {

				ret = DALIST_EMEMFN;

			}

			break;

		default:

			ret = DALIST_EINTERNAL;

			break;

	}

	return ret;

}