/*
* High Resolution Timestamp Entropy Source
* (C) 1999-2009 Jack Lloyd
*
* Distributed under the terms of the Botan license
*/

#include <botan/internal/hres_timer.h>
#include <botan/cpuid.h>
#include <botan/time.h>

#if defined(BOTAN_TARGET_OS_IS_WINDOWS)
  #include <windows.h>
#endif

namespace Botan {

/*
* Get the timestamp
*/
void High_Resolution_Timestamp::poll(Entropy_Accumulator& accum)
   {
   // If Windows, grab the Performance Counter (usually TSC or PIT)
#if defined(BOTAN_TARGET_OS_IS_WINDOWS)
   LARGE_INTEGER tv;
   ::QueryPerformanceCounter(&tv);
   accum.add(tv.QuadPart, 0);
#endif

#if BOTAN_USE_GCC_INLINE_ASM

   u64bit rtc = 0;

#if defined(BOTAN_TARGET_CPU_IS_X86_FAMILY)
   if(CPUID::has_rdtsc()) // not availble on all x86 CPUs
      {
      size_t rtc_low = 0, rtc_high = 0;
      asm volatile("rdtsc" : "=d" (rtc_high), "=a" (rtc_low));
      rtc = (static_cast<u64bit>(rtc_high) << 32) | rtc_low;
      }

#elif defined(BOTAN_TARGET_CPU_IS_PPC_FAMILY)
   size_t rtc_low = 0, rtc_high = 0;
   asm volatile("mftbu %0; mftb %1" : "=r" (rtc_high), "=r" (rtc_low));
   rtc = (static_cast<u64bit>(rtc_high) << 32) | rtc_low;

#elif defined(BOTAN_TARGET_ARCH_IS_ALPHA)
   asm volatile("rpcc %0" : "=r" (rtc));

#elif defined(BOTAN_TARGET_ARCH_IS_SPARC64)
   asm volatile("rd %%tick, %0" : "=r" (rtc));

#elif defined(BOTAN_TARGET_ARCH_IS_IA64)
   asm volatile("mov %0=ar.itc" : "=r" (rtc));

#elif defined(BOTAN_TARGET_ARCH_IS_S390X)
   asm volatile("stck 0(%0)" : : "a" (&rtc) : "memory", "cc");

#elif defined(BOTAN_TARGET_ARCH_IS_HPPA)
   asm volatile("mfctl 16,%0" : "=r" (rtc)); // 64-bit only?

#endif

   // Don't count the timestamp as contributing entropy
   accum.add(rtc, 0);

#endif
   }

}