hardware.h revision 292588 
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 */
50extern LZMA_API(uint64_t) lzma_physmem(void) lzma_nothrow;
51
52
53/**
54 * \brief       Get the number of processor cores or threads
55 *
56 * This function may be useful when determining how many threads to use.
57 * If the hardware supports more than one thread per CPU core, the number
58 * of hardware threads is returned if that information is available.
59 *
60 * \brief       On success, the number of available CPU threads or cores is
61 *              returned. If this information isn't available or an error
62 *              occurs, zero is returned.
63 */
64extern LZMA_API(uint32_t) lzma_cputhreads(void) lzma_nothrow;
65