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.
  //    For Linux and Unix additional flags are not required.
  
  #include "pch.h"
  #include "config.h"
  #include "stdcpp.h"
  
  #if (CRYPTOPP_ARM_NEON_HEADER)
  # include <arm_neon.h>
  #endif
  
  #if (CRYPTOPP_ARM_ACLE_HEADER)
  # 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(__aarch32__) || defined(__aarch64__) || defined(_M_ARM64)
      return false;
  #elif 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;
  # 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))
      {
          signal(SIGILL, oldHandler);
          return false;
      }
  
      if (setjmp(s_jmpSIGILL))
          result = false;
      else
      {
  
  #if 0
          // ARMv7 added movt and movw
          int a;
          asm volatile("movw %0,%1 \n"
                       "movt %0,%1 \n"
                       : "=r"(a) : "i"(0x1234));
  
  00000010 <_Z5test2v>:  // ARM
    10:   e3010234        movw    r0, #4660       ; 0x1234
    14:   e3410234        movt    r0, #4660       ; 0x1234
    18:   e12fff1e        bx      lr
  
  0000001c <_Z5test3v>:  // Thumb
    1c:   f241 2034       movw    r0, #4660       ; 0x1234
    20:   f2c1 2034       movt    r0, #4660       ; 0x1234
    24:   e12fff1e        bx      lr
  #endif
  
          unsigned int a;
          asm volatile (
  #if defined(__thumb__)
              ".inst.n 0xf241, 0x2034  \n\t"   // movw r0, 0x1234
              ".inst.n 0xf2c1, 0x2034  \n\t"   // movt r0, 0x1234
              "mov %0, r0              \n\t"   // mov [a], r0
  #else
              ".inst 0xe3010234  \n\t"   // movw r0, 0x1234
              ".inst 0xe3410234  \n\t"   // movt r0, 0x1234
              "mov %0, r0        \n\t"   // mov [a], r0
  #endif
              : "=r" (a) : : "r0");
  
          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(__aarch32__) || defined(__aarch64__) || defined(_M_ARM64)
      return true;
  #elif 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
      {
          uint32x4_t x = vdupq_n_u32(1);
          uint32x4_t y = vshlq_n_u32(x, 4);
  
          word32 z[4]; vst1q_u32(z, y);
          return (z[0] & z[1] & z[2] & z[3]) == 16;
      }
      __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))
      {
          signal(SIGILL, oldHandler);
          return false;
      }
  
      if (setjmp(s_jmpSIGILL))
          result = false;
      else
      {
          // This is risky... When we hand encode the instructions
          // for vmov.u32 and vshl.u32 we get a SIGILL. Apparently
          // we need more than just the instructions. Using
          // intrinsics introduces the risk because the whole
          // file gets built with ISA options, and the higher ISA
          // may escape the try block with the SIGILL guard.
          uint32x4_t x = vdupq_n_u32(1);
          uint32x4_t y = vshlq_n_u32(x, 4);
  
          word32 z[4]; vst1q_u32(z, y);
          result = (z[0] & z[1] & z[2] & z[3]) == 16;
      }
  
      sigprocmask(SIG_SETMASK, (sigset_t*)&oldMask, NULLPTR);
      signal(SIGILL, oldHandler);
      return result;
  # endif
  #else
      return false;
  #endif  // CRYPTOPP_ARM_NEON_AVAILABLE
  }
  
  NAMESPACE_END
  