1 /* SPDX-License-Identifier: 0BSD */ 2 3 /** 4 * \file lzma/hardware.h 5 * \brief Hardware information 6 * \note Never include this file directly. Use <lzma.h> instead. 7 * 8 * Since liblzma can consume a lot of system resources, it also provides 9 * ways to limit the resource usage. Applications linking against liblzma 10 * need to do the actual decisions how much resources to let liblzma to use. 11 * To ease making these decisions, liblzma provides functions to find out 12 * the relevant capabilities of the underlying hardware. Currently there 13 * is only a function to find out the amount of RAM, but in the future there 14 * will be also a function to detect how many concurrent threads the system 15 * can run. 16 * 17 * \note On some operating systems, these function may temporarily 18 * load a shared library or open file descriptor(s) to find out 19 * the requested hardware information. Unless the application 20 * assumes that specific file descriptors are not touched by 21 * other threads, this should have no effect on thread safety. 22 * Possible operations involving file descriptors will restart 23 * the syscalls if they return EINTR. 24 */ 25 26 /* 27 * Author: Lasse Collin 28 */ 29 30 #ifndef LZMA_H_INTERNAL 31 # error Never include this file directly. Use <lzma.h> instead. 32 #endif 33 34 35 /** 36 * \brief Get the total amount of physical memory (RAM) in bytes 37 * 38 * This function may be useful when determining a reasonable memory 39 * usage limit for decompressing or how much memory it is OK to use 40 * for compressing. 41 * 42 * \return On success, the total amount of physical memory in bytes 43 * is returned. If the amount of RAM cannot be determined, 44 * zero is returned. This can happen if an error occurs 45 * or if there is no code in liblzma to detect the amount 46 * of RAM on the specific operating system. 47 */ 48 extern LZMA_API(uint64_t) lzma_physmem(void) lzma_nothrow; 49 50 51 /** 52 * \brief Get the number of processor cores or threads 53 * 54 * This function may be useful when determining how many threads to use. 55 * If the hardware supports more than one thread per CPU core, the number 56 * of hardware threads is returned if that information is available. 57 * 58 * \return On success, the number of available CPU threads or cores is 59 * returned. If this information isn't available or an error 60 * occurs, zero is returned. 61 */ 62 extern LZMA_API(uint32_t) lzma_cputhreads(void) lzma_nothrow; 63