xref: /freebsd/contrib/xz/src/liblzma/api/lzma/hardware.h (revision 9a14aa017b21c292740c00ee098195cd46642730)
1 /**
2  * \file        lzma/hardware.h
3  * \brief       Hardware information
4  *
5  * Since liblzma can consume a lot of system resources, it also provides
6  * ways to limit the resource usage. Applications linking against liblzma
7  * need to do the actual decisions how much resources to let liblzma to use.
8  * To ease making these decisions, liblzma provides functions to find out
9  * the relevant capabilities of the underlaying hardware. Currently there
10  * is only a function to find out the amount of RAM, but in the future there
11  * will be also a function to detect how many concurrent threads the system
12  * can run.
13  *
14  * \note        On some operating systems, these function may temporarily
15  *              load a shared library or open file descriptor(s) to find out
16  *              the requested hardware information. Unless the application
17  *              assumes that specific file descriptors are not touched by
18  *              other threads, this should have no effect on thread safety.
19  *              Possible operations involving file descriptors will restart
20  *              the syscalls if they return EINTR.
21  */
22 
23 /*
24  * Author: Lasse Collin
25  *
26  * This file has been put into the public domain.
27  * You can do whatever you want with this file.
28  *
29  * See ../lzma.h for information about liblzma as a whole.
30  */
31 
32 #ifndef LZMA_H_INTERNAL
33 #	error Never include this file directly. Use <lzma.h> instead.
34 #endif
35 
36 
37 /**
38  * \brief       Get the total amount of physical memory (RAM) in bytes
39  *
40  * This function may be useful when determining a reasonable memory
41  * usage limit for decompressing or how much memory it is OK to use
42  * for compressing.
43  *
44  * \return      On success, the total amount of physical memory in bytes
45  *              is returned. If the amount of RAM cannot be determined,
46  *              zero is returned. This can happen if an error occurs
47  *              or if there is no code in liblzma to detect the amount
48  *              of RAM on the specific operating system.
49  */
50 extern LZMA_API(uint64_t) lzma_physmem(void) lzma_nothrow;
51