cpu-large-page-size.cpp

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#include <cstddef>
#include <iostream>
 
#if defined(__i386__) || defined(__x86_64__)
 
#include <cpuid.h>
 
/* Features in %edx for leaf 1 */
#if !defined(bit_PSE)
#define bit_PSE 0x00000008
#endif
#if !defined(bit_PAE)
#define bit_PAE 0x00000040
#endif
 
int main() {
  unsigned int eax;
  unsigned int ebx;
  unsigned int ecx;
  unsigned int edx;
 
  if (!__get_cpuid(1, &eax, &ebx, &ecx, &edx))
    return 1; // Detection failed.
 
  size_t val;
  if (edx & bit_PAE)
    val = 2 * 1024 * 1024; // 2 MiB
  else if (edx & bit_PSE)
    val = 4 * 1024 * 1024; // 4 MiB
  else
    val = 4 * 1024; // 4 KiB
 
  std::cout << val << std::endl;
  return 0;
}
 
#else
 
int main() {
  // Don't know how to perform detection. Just fall back to page size.
  std::cout << RAWSPEED_PAGESIZE << std::endl;
  return 0;
}
 
#endif