1 /* -*- mode: C; c-basic-offset: 4; indent-tabs-mode: nil -*- */
2 // vim: expandtab:ts=8:sw=4:softtabstop=4:
3 ///////////////////////////////////////////////////////////////////////////////
4 //
5 /// \file physmem.h
6 /// \brief Get the amount of physical memory
7 //
8 // Author: Lasse Collin
9 //
10 // This file has been put into the public domain.
11 // You can do whatever you want with this file.
12 //
13 ///////////////////////////////////////////////////////////////////////////////
14
15 #ifndef PHYSMEM_H
16 #define PHYSMEM_H
17
18 // Test for Windows first, because we want to use Windows-specific code
19 // on Cygwin, which also has memory information available via sysconf(), but
20 // on Cygwin 1.5 and older it gives wrong results (from our point of view).
21 #if defined(_WIN32) || defined(__CYGWIN__)
22 # ifndef _WIN32_WINNT
23 # define _WIN32_WINNT 0x0500
24 # endif
25 # include <windows.h>
26
27 #elif defined(HAVE_PHYSMEM_SYSCONF)
28 # include <unistd.h>
29
30 #elif defined(HAVE_PHYSMEM_SYSCTL)
31 # ifdef HAVE_SYS_PARAM_H
32 # include <sys/param.h>
33 # endif
34 # ifdef HAVE_SYS_SYSCTL_H
35 # include <sys/sysctl.h>
36 # endif
37
38 #elif defined(HAVE_PHYSMEM_SYSINFO)
39 # include <sys/sysinfo.h>
40
41 #elif defined(__DJGPP__)
42 # include <dpmi.h>
43 #endif
44
45
46 /// \brief Get the amount of physical memory in bytes
47 ///
48 /// \return Amount of physical memory in bytes. On error, zero is
49 /// returned.
50 static inline uint64_t
physmem(void)51 physmem(void)
52 {
53 uint64_t ret = 0;
54
55 #if defined(_WIN32) || defined(__CYGWIN__)
56 if ((GetVersion() & 0xFF) >= 5) {
57 // Windows 2000 and later have GlobalMemoryStatusEx() which
58 // supports reporting values greater than 4 GiB. To keep the
59 // code working also on older Windows versions, use
60 // GlobalMemoryStatusEx() conditionally.
61 HMODULE kernel32 = GetModuleHandle("kernel32.dll");
62 if (kernel32 != NULL) {
63 BOOL (WINAPI *gmse)(LPMEMORYSTATUSEX) = GetProcAddress(
64 kernel32, "GlobalMemoryStatusEx");
65 if (gmse != NULL) {
66 MEMORYSTATUSEX meminfo;
67 meminfo.dwLength = sizeof(meminfo);
68 if (gmse(&meminfo))
69 ret = meminfo.ullTotalPhys;
70 }
71 }
72 }
73
74 if (ret == 0) {
75 // GlobalMemoryStatus() is supported by Windows 95 and later,
76 // so it is fine to link against it unconditionally. Note that
77 // GlobalMemoryStatus() has no return value.
78 MEMORYSTATUS meminfo;
79 meminfo.dwLength = sizeof(meminfo);
80 GlobalMemoryStatus(&meminfo);
81 ret = meminfo.dwTotalPhys;
82 }
83
84 #elif defined(HAVE_PHYSMEM_SYSCONF)
85 const long pagesize = sysconf(_SC_PAGESIZE);
86 const long pages = sysconf(_SC_PHYS_PAGES);
87 if (pagesize != -1 || pages != -1)
88 // According to docs, pagesize * pages can overflow.
89 // Simple case is 32-bit box with 4 GiB or more RAM,
90 // which may report exactly 4 GiB of RAM, and "long"
91 // being 32-bit will overflow. Casting to uint64_t
92 // hopefully avoids overflows in the near future.
93 ret = (uint64_t)(pagesize) * (uint64_t)(pages);
94
95 #elif defined(HAVE_PHYSMEM_SYSCTL)
96 int name[2] = {
97 CTL_HW,
98 #ifdef HW_PHYSMEM64
99 HW_PHYSMEM64
100 #else
101 HW_PHYSMEM
102 #endif
103 };
104 union {
105 uint32_t u32;
106 uint64_t u64;
107 } mem;
108 size_t mem_ptr_size = sizeof(mem.u64);
109 if (!sysctl(name, 2, &mem.u64, &mem_ptr_size, NULL, NULL)) {
110 // IIRC, 64-bit "return value" is possible on some 64-bit
111 // BSD systems even with HW_PHYSMEM (instead of HW_PHYSMEM64),
112 // so support both.
113 if (mem_ptr_size == sizeof(mem.u64))
114 ret = mem.u64;
115 else if (mem_ptr_size == sizeof(mem.u32))
116 ret = mem.u32;
117 }
118
119 #elif defined(HAVE_PHYSMEM_SYSINFO)
120 struct sysinfo si;
121 if (sysinfo(&si) == 0)
122 ret = (uint64_t)(si.totalram) * si.mem_unit;
123
124 #elif defined(__DJGPP__)
125 __dpmi_free_mem_info meminfo;
126 if (__dpmi_get_free_memory_information(&meminfo) == 0
127 && meminfo.total_number_of_physical_pages
128 != (unsigned long)(-1))
129 ret = (uint64_t)(meminfo.total_number_of_physical_pages)
130 * 4096;
131 #endif
132
133 return ret;
134 }
135
136 #endif
137