text: // crc-simd.cpp - written and placed in the public domain by
  //                Jeffrey Walton, Uri Blumenthal and Marcel Raad.
  //
  //    This source file uses intrinsics to gain access to ARMv7a and
  //    ARMv8a NEON instructions. A separate source file is needed
  //    because additional CXXFLAGS are required to enable the
  //    appropriate instructions sets in some build configurations.
  
  #include "pch.h"
  #include "config.h"
  #include "stdcpp.h"
  
  #if (CRYPTOPP_ARM_NEON_AVAILABLE)
  # include <arm_neon.h>
  #endif
  
  // Can't use CRYPTOPP_ARM_XXX_AVAILABLE because too many
  // compilers don't follow ACLE conventions for the include.
  #if defined(CRYPTOPP_ARM_ACLE_AVAILABLE)
  # include <stdint.h>
  # include <arm_acle.h>
  #endif
  
  #ifdef CRYPTOPP_GNU_STYLE_INLINE_ASSEMBLY
  # include <signal.h>
  # include <setjmp.h>
  #endif
  
  #ifndef EXCEPTION_EXECUTE_HANDLER
  # define EXCEPTION_EXECUTE_HANDLER 1
  #endif
  
  // Squash MS LNK4221 and libtool warnings
  extern const char NEON_SIMD_FNAME[] = __FILE__;
  
  NAMESPACE_BEGIN(CryptoPP)
  
  #ifdef CRYPTOPP_GNU_STYLE_INLINE_ASSEMBLY
  extern "C" {
      typedef void (*SigHandler)(int);
  
  	static jmp_buf s_jmpSIGILL;
  	static void SigIllHandler(int)
  	{
  		longjmp(s_jmpSIGILL, 1);
  	}
  }
  #endif  // Not CRYPTOPP_MS_STYLE_INLINE_ASSEMBLY
  
  bool CPU_ProbeARMv7()
  {
  #if defined(CRYPTOPP_NO_CPU_FEATURE_PROBES)
  	return false;
  #elif (CRYPTOPP_ARM_NEON_AVAILABLE)
  # if defined(CRYPTOPP_MS_STYLE_INLINE_ASSEMBLY)
  	volatile bool result = true;
  	__try
  	{
  		// Modern MS hardware is ARMv7
  		result = true;
  	}
  	__except (EXCEPTION_EXECUTE_HANDLER)
  	{
  		return false;
  	}
  	return result;
  # elif defined(__arm__)
  	// longjmp and clobber warnings. Volatile is required.
  	// http://github.com/weidai11/cryptopp/issues/24 and http://stackoverflow.com/q/7721854
  	volatile bool result = true;
  
  	volatile SigHandler oldHandler = signal(SIGILL, SigIllHandler);
  	if (oldHandler == SIG_ERR)
  		return false;
  
  	volatile sigset_t oldMask;
  	if (sigprocmask(0, NULLPTR, (sigset_t*)&oldMask))
  		return false;
  
  	if (setjmp(s_jmpSIGILL))
  		result = false;
  	else
  	{
  		// ARMv7 added movt and movw
  		int a;
  		asm volatile("movw %0,%1 \n"
  					 "movt %0,%1 \n"
  					 : "=r"(a) : "i"(0x1234));
  		result = (a == 0x12341234);
  	}
  
  	sigprocmask(SIG_SETMASK, (sigset_t*)&oldMask, NULLPTR);
  	signal(SIGILL, oldHandler);
  	return result;
  # endif
  #else
  	return false;
  #endif  // CRYPTOPP_ARM_NEON_AVAILABLE
  }
  
  bool CPU_ProbeNEON()
  {
  #if defined(CRYPTOPP_NO_CPU_FEATURE_PROBES)
  	return false;
  #elif (CRYPTOPP_ARM_NEON_AVAILABLE)
  # if defined(CRYPTOPP_MS_STYLE_INLINE_ASSEMBLY)
  	volatile bool result = true;
  	__try
  	{
  		uint32_t v1[4] = {1,1,1,1};
  		uint32x4_t x1 = vld1q_u32(v1);
  		uint64_t v2[2] = {1,1};
  		uint64x2_t x2 = vld1q_u64(v2);
  
  		uint32x4_t x3 = vdupq_n_u32(2);
  		x3 = vsetq_lane_u32(vgetq_lane_u32(x1,0),x3,0);
  		x3 = vsetq_lane_u32(vgetq_lane_u32(x1,3),x3,3);
  		uint64x2_t x4 = vdupq_n_u64(2);
  		x4 = vsetq_lane_u64(vgetq_lane_u64(x2,0),x4,0);
  		x4 = vsetq_lane_u64(vgetq_lane_u64(x2,1),x4,1);
  
  		result = !!(vgetq_lane_u32(x3,0) | vgetq_lane_u64(x4,1));
  	}
  	__except (EXCEPTION_EXECUTE_HANDLER)
  	{
  		return false;
  	}
  	return result;
  # else
  
  	// longjmp and clobber warnings. Volatile is required.
  	// http://github.com/weidai11/cryptopp/issues/24 and http://stackoverflow.com/q/7721854
  	volatile bool result = true;
  
  	volatile SigHandler oldHandler = signal(SIGILL, SigIllHandler);
  	if (oldHandler == SIG_ERR)
  		return false;
  
  	volatile sigset_t oldMask;
  	if (sigprocmask(0, NULLPTR, (sigset_t*)&oldMask))
  		return false;
  
  	if (setjmp(s_jmpSIGILL))
  		result = false;
  	else
  	{
  		uint32_t v1[4] = {1,1,1,1};
  		uint32x4_t x1 = vld1q_u32(v1);
  		uint64_t v2[2] = {1,1};
  		uint64x2_t x2 = vld1q_u64(v2);
  
  		uint32x4_t x3 = {0,0,0,0};
  		x3 = vsetq_lane_u32(vgetq_lane_u32(x1,0),x3,0);
  		x3 = vsetq_lane_u32(vgetq_lane_u32(x1,3),x3,3);
  		uint64x2_t x4 = {0,0};
  		x4 = vsetq_lane_u64(vgetq_lane_u64(x2,0),x4,0);
  		x4 = vsetq_lane_u64(vgetq_lane_u64(x2,1),x4,1);
  
  		// Hack... GCC optimizes away the code and returns true
  		result = !!(vgetq_lane_u32(x3,0) | vgetq_lane_u64(x4,1));
  	}
  
  	sigprocmask(SIG_SETMASK, (sigset_t*)&oldMask, NULLPTR);
  	signal(SIGILL, oldHandler);
  	return result;
  # endif
  #else
  	return false;
  #endif  // CRYPTOPP_ARM_NEON_AVAILABLE
  }
  
  NAMESPACE_END
  