#
core/stdarch/crates/core_arch/src/x86/
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#![allow(clippy::module_name_repetitions)]
    5
    6#[allow(improper_ctypes)]
    7unsafe extern "unadjusted" {
    8    #[link_name = "llvm.x86.rdrand.16"]
    9    fn x86_rdrand16_step() -> (u16, i32);
    10    #[link_name = "llvm.x86.rdrand.32"]
    11    fn x86_rdrand32_step() -> (u32, i32);
    12    #[link_name = "llvm.x86.rdseed.16"]
    13    fn x86_rdseed16_step() -> (u16, i32);
    14    #[link_name = "llvm.x86.rdseed.32"]
    15    fn x86_rdseed32_step() -> (u32, i32);
    16}
    17
    18#[cfg(test)]
    19use stdarch_test::assert_instr;
    20
    21/// Read a hardware generated 16-bit random value and store the result in val.
    22/// Returns 1 if a random value was generated, and 0 otherwise.
    23///
    24/// [Intel's documentation](https://www.intel.com/content/www/us/en/docs/intrinsics-guide/index.html#text=_rdrand16_step)
    25#[inline]
    26#[target_feature(enable = "rdrand")]
    27#[cfg_attr(test, assert_instr(rdrand))]
    28#[stable(feature = "simd_x86", since = "1.27.0")]
    29pub unsafe fn _rdrand16_step(val: &mut u16) -> i32 {
    30    let (v, flag) = x86_rdrand16_step();
    31    *val = v;
    32    flag
    33}
    34
    35/// Read a hardware generated 32-bit random value and store the result in val.
    36/// Returns 1 if a random value was generated, and 0 otherwise.
    37///
    38/// [Intel's documentation](https://www.intel.com/content/www/us/en/docs/intrinsics-guide/index.html#text=_rdrand32_step)
    39#[inline]
    40#[target_feature(enable = "rdrand")]
    41#[cfg_attr(test, assert_instr(rdrand))]
    42#[stable(feature = "simd_x86", since = "1.27.0")]
    43pub unsafe fn _rdrand32_step(val: &mut u32) -> i32 {
    44    let (v, flag) = x86_rdrand32_step();
    45    *val = v;
    46    flag
    47}
    48
    49/// Read a 16-bit NIST SP800-90B and SP800-90C compliant random value and store
    50/// in val. Return 1 if a random value was generated, and 0 otherwise.
    51///
    52/// [Intel's documentation](https://www.intel.com/content/www/us/en/docs/intrinsics-guide/index.html#text=_rdseed16_step)
    53#[inline]
    54#[target_feature(enable = "rdseed")]
    55#[cfg_attr(test, assert_instr(rdseed))]
    56#[stable(feature = "simd_x86", since = "1.27.0")]
    57pub unsafe fn _rdseed16_step(val: &mut u16) -> i32 {
    58    let (v, flag) = x86_rdseed16_step();
    59    *val = v;
    60    flag
    61}
    62
    63/// Read a 32-bit NIST SP800-90B and SP800-90C compliant random value and store
    64/// in val. Return 1 if a random value was generated, and 0 otherwise.
    65///
    66/// [Intel's documentation](https://www.intel.com/content/www/us/en/docs/intrinsics-guide/index.html#text=_rdseed32_step)
    67#[inline]
    68#[target_feature(enable = "rdseed")]
    69#[cfg_attr(test, assert_instr(rdseed))]
    70#[stable(feature = "simd_x86", since = "1.27.0")]
    71pub unsafe fn _rdseed32_step(val: &mut u32) -> i32 {
    72    let (v, flag) = x86_rdseed32_step();
    73    *val = v;
    74    flag
    75}