library/stdarch/crates/core_arch/src/x86_64/rdrand.rs

   1 //! RDRAND and RDSEED instructions for returning random numbers from an Intel
   2 //! on-chip hardware random number generator which has been seeded by an
   3 //! on-chip entropy source.
   4
   5 #![allow(clippy::module_name_repetitions)]
   6
   7 #[allow(improper_ctypes)]
   8 extern "unadjusted" {
   9     #[link_name = "llvm.x86.rdrand.64"]
  10     fn x86_rdrand64_step() -> (u64, i32);
  11     #[link_name = "llvm.x86.rdseed.64"]
  12     fn x86_rdseed64_step() -> (u64, i32);
  13 }
  14
  15 #[cfg(test)]
  16 use stdarch_test::assert_instr;
  17
  18 /// Read a hardware generated 64-bit random value and store the result in val.
  19 /// Returns 1 if a random value was generated, and 0 otherwise.
  20 ///
  21 /// [Intel's documentation](https://software.intel.com/sites/landingpage/IntrinsicsGuide/#text=_rdrand64_step)
  22 #[inline]
  23 #[target_feature(enable = "rdrand")]
  24 #[cfg_attr(test, assert_instr(rdrand))]
  25 #[stable(feature = "simd_x86", since = "1.27.0")]
  26 pub unsafe fn _rdrand64_step(val: &mut u64) -> i32 {
  27     let (v, flag) = x86_rdrand64_step();
  28     *val = v;
  29     flag
  30 }
  31
  32 /// Read a 64-bit NIST SP800-90B and SP800-90C compliant random value and store
  33 /// in val. Return 1 if a random value was generated, and 0 otherwise.
  34 ///
  35 /// [Intel's documentation](https://software.intel.com/sites/landingpage/IntrinsicsGuide/#text=_rdseed64_step)
  36 #[inline]
  37 #[target_feature(enable = "rdseed")]
  38 #[cfg_attr(test, assert_instr(rdseed))]
  39 #[stable(feature = "simd_x86", since = "1.27.0")]
  40 pub unsafe fn _rdseed64_step(val: &mut u64) -> i32 {
  41     let (v, flag) = x86_rdseed64_step();
  42     *val = v;
  43     flag
  44 }