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///////////////////////////////////////////////////////////////////////////////
//
/// \file physmem.h
/// \brief Get the amount of physical memory
//
// This code has been put into the public domain.
//
// This library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
//
///////////////////////////////////////////////////////////////////////////////
#ifndef PHYSMEM_H
#define PHYSMEM_H
#if defined(HAVE_PHYSMEM_SYSCTL) || defined(HAVE_NCPU_SYSCTL)
# ifdef HAVE_SYS_PARAM_H
# include <sys/param.h>
# endif
# ifdef HAVE_SYS_SYSCTL_H
# include <sys/sysctl.h>
# endif
#endif
#if defined(HAVE_PHYSMEM_SYSCONF) || defined(HAVE_NCPU_SYSCONF)
# include <unistd.h>
#endif
#ifdef _WIN32
# ifndef _WIN32_WINNT
# define _WIN32_WINNT 0x0500
# endif
# include <windows.h>
#endif
#ifdef __DJGPP__
# include <dpmi.h>
#endif
/// \brief Get the amount of physical memory in bytes
///
/// \return Amount of physical memory in bytes. On error, zero is
/// returned.
static inline uint64_t
physmem(void)
{
uint64_t ret = 0;
#if defined(HAVE_PHYSMEM_SYSCONF)
const long pagesize = sysconf(_SC_PAGESIZE);
const long pages = sysconf(_SC_PHYS_PAGES);
if (pagesize != -1 || pages != -1)
// According to docs, pagesize * pages can overflow.
// Simple case is 32-bit box with 4 GiB or more RAM,
// which may report exactly 4 GiB of RAM, and "long"
// being 32-bit will overflow. Casting to uint64_t
// hopefully avoids overflows in the near future.
ret = (uint64_t)(pagesize) * (uint64_t)(pages);
#elif defined(HAVE_PHYSMEM_SYSCTL)
int name[2] = { CTL_HW, HW_PHYSMEM };
union {
unsigned long ul;
unsigned int ui;
} mem;
size_t mem_ptr_size = sizeof(mem.ul);
if (!sysctl(name, 2, &mem.ul, &mem_ptr_size, NULL, NULL)) {
// Some systems use unsigned int as the "return value".
// This makes a difference on 64-bit boxes.
if (mem_ptr_size == sizeof(mem.ul))
ret = mem.ul;
else if (mem_ptr_size == sizeof(mem.ui))
ret = mem.ui;
}
#elif defined(_WIN32)
MEMORYSTATUSEX meminfo;
meminfo.dwLength = sizeof(meminfo);
if (GlobalMemoryStatusEx(&meminfo))
ret = meminfo.ullTotalPhys;
#elif defined(__DJGPP__)
__dpmi_free_mem_info meminfo;
if (__dpmi_get_free_memory_information(&meminfo) == 0
&& meminfo.total_number_of_physical_pages
!= (unsigned long)(-1))
ret = (uint64_t)(meminfo.total_number_of_physical_pages)
* 4096;
#endif
return ret;
}
#endif
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