/*
* Runtime CPU detection for POWER/PowerPC
* (C) 2009,2010,2013,2017 Jack Lloyd
*
* Botan is released under the Simplified BSD License (see license.txt)
*/

#include <botan/cpuid.h>
#include <botan/internal/os_utils.h>

#if defined(BOTAN_TARGET_CPU_IS_PPC_FAMILY)

/*
* On Darwin and OpenBSD ppc, use sysctl to detect AltiVec
*/
#if defined(BOTAN_TARGET_OS_IS_DARWIN)
  #include <sys/sysctl.h>
#elif defined(BOTAN_TARGET_OS_IS_OPENBSD)
  #include <sys/param.h>
  #include <sys/sysctl.h>
  #include <machine/cpu.h>
#endif

#endif

namespace Botan {

#if defined(BOTAN_TARGET_CPU_IS_PPC_FAMILY)

/*
* PowerPC specific block: check for AltiVec using either
* sysctl or by reading processor version number register.
*/
uint64_t CPUID::detect_cpu_features(size_t* cache_line_size)
   {
#if defined(BOTAN_TARGET_OS_IS_DARWIN) || defined(BOTAN_TARGET_OS_IS_OPENBSD)
   // On Darwin/OS X and OpenBSD, use sysctl

   int sels[2] = {
#if defined(BOTAN_TARGET_OS_IS_OPENBSD)
      CTL_MACHDEP, CPU_ALTIVEC
#else
      CTL_HW, HW_VECTORUNIT
#endif
   };

   int vector_type = 0;
   size_t length = sizeof(vector_type);
   int error = ::sysctl(sels, 2, &vector_type, &length, NULL, 0);

   if(error == 0 && vector_type > 0)
      return CPUID::CPUID_ALTIVEC_BIT;

#else

   /*
   On PowerPC, MSR 287 is PVR, the Processor Version Number
   Normally it is only accessible to ring 0, but Linux and NetBSD
   (others, too, maybe?) will trap and emulate it for us.
   */

   int pvr = OS::run_cpu_instruction_probe([]() -> int {
      uint32_t pvr = 0;
      asm volatile("mfspr %0, 287" : "=r" (pvr));
      // Top 16 bits suffice to identify the model
      return static_cast<int>(pvr >> 16);
      });

   if(pvr > 0)
      {
      const uint16_t ALTIVEC_PVR[] = {
         0x003E, // IBM POWER6,
         0x003F, // IBM POWER7,
         0x004B, // IBM POWER8,
         0x000C, // G4-7400
         0x0039, // G5 970
         0x003C, // G5 970FX
         0x0044, // G5 970MP
         0x0070, // Cell PPU
         0, // end
      };

      for(size_t i = 0; ALTIVEC_PVR[i]; ++i)
         {
         if(pvr == ALTIVEC_PVR[i])
            return CPUID::CPUID_ALTIVEC_BIT;
         }

      return 0;
      }

   // TODO try direct instruction probing

#endif

   return 0;
   }

#endif

}