Current File : //data/old/usr/include/libowfat/iarray.h
/* this header file comes from libowfat, http://www.fefe.de/libowfat/ */
#ifndef IARRAY_H
#define IARRAY_H
/* This header defines an indirect array for use with the io_* routines.
* Assumptions:
* - the elements are small (many fit on one page),
* - the platform has an atomic compare-and-swap instruction
* - the compiler supports it via __sync_val_compare_and_swap
*/
#include "uint64.h"
#include <stddef.h>
#ifdef __MINGW32__
#include <windows.h>
#else
#include <pthread.h>
#endif
/* The basic data structure is a static array of pointers to pages.
* Each page also contains a next pointer to form a linked list.
* To get to element n, you take n % the number of elements in the
* static array (iarray->pages) to get to the list of pages that
* contains it. Then keep going to the next page until you are on the
* right page.
* Note: The elements on each page are not contiguous. If the fanout is
* 16, the indices on page 0 are 0, 16, 32, ...
* To get to element 0, you'd go to iarray->pages[0].data,
* to get to element 1, you'd go to iarray->pages[1].data,
* to get to element 16, you'd go to iarray->pages[0].data+iarray->elemsize.
*/
typedef struct _iarray_page {
struct _iarray_page* next;
char data[];
} iarray_page;
typedef struct {
iarray_page* pages[16];
size_t elemsize,elemperpage,bytesperpage,len;
} iarray;
void iarray_init(iarray* ia,size_t elemsize);
void* iarray_get(iarray* ia,size_t pos);
void* iarray_allocate(iarray* ia,size_t pos);
size_t iarray_length(iarray* ia);
/* WARNING: do not use the array during or after iarray_free, make sure
* no threads are potentially doing anything with the iarray while it is
* being freed! */
void iarray_free(iarray* ia);
#endif
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