src/common/physmem.h

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