library/stdarch/crates/core_arch/src/x86/eflags.rs

   1 //! `i386` intrinsics
   2
   3 /// Reads EFLAGS.
   4 ///
   5 /// [Intel's documentation](https://software.intel.com/sites/landingpage/IntrinsicsGuide/#text=__readeflags)
   6 #[cfg(target_arch = "x86")]
   7 #[inline(always)]
   8 #[stable(feature = "simd_x86", since = "1.27.0")]
   9 #[rustc_deprecated(
  10     since = "1.29.0",
  11     reason = "See issue #51810 - use inline assembly instead"
  12 )]
  13 #[doc(hidden)]
  14 pub unsafe fn __readeflags() -> u32 {
  15     let eflags: u32;
  16     asm!("pushfd", "pop {}", out(reg) eflags, options(nomem, att_syntax));
  17     eflags
  18 }
  19
  20 /// Reads EFLAGS.
  21 ///
  22 /// [Intel's documentation](https://software.intel.com/sites/landingpage/IntrinsicsGuide/#text=__readeflags)
  23 #[cfg(target_arch = "x86_64")]
  24 #[inline(always)]
  25 #[stable(feature = "simd_x86", since = "1.27.0")]
  26 #[rustc_deprecated(
  27     since = "1.29.0",
  28     reason = "See issue #51810 - use inline assembly instead"
  29 )]
  30 #[doc(hidden)]
  31 pub unsafe fn __readeflags() -> u64 {
  32     let eflags: u64;
  33     asm!("pushfq", "pop {}", out(reg) eflags, options(nomem, att_syntax));
  34     eflags
  35 }
  36
  37 /// Write EFLAGS.
  38 ///
  39 /// [Intel's documentation](https://software.intel.com/sites/landingpage/IntrinsicsGuide/#text=__writeeflags)
  40 #[cfg(target_arch = "x86")]
  41 #[inline(always)]
  42 #[stable(feature = "simd_x86", since = "1.27.0")]
  43 #[rustc_deprecated(
  44     since = "1.29.0",
  45     reason = "See issue #51810 - use inline assembly instead"
  46 )]
  47 #[doc(hidden)]
  48 pub unsafe fn __writeeflags(eflags: u32) {
  49     asm!("push {}", "popfd", in(reg) eflags, options(nomem, att_syntax));
  50 }
  51
  52 /// Write EFLAGS.
  53 ///
  54 /// [Intel's documentation](https://software.intel.com/sites/landingpage/IntrinsicsGuide/#text=__writeeflags)
  55 #[cfg(target_arch = "x86_64")]
  56 #[inline(always)]
  57 #[stable(feature = "simd_x86", since = "1.27.0")]
  58 #[rustc_deprecated(
  59     since = "1.29.0",
  60     reason = "See issue #51810 - use inline assembly instead"
  61 )]
  62 #[doc(hidden)]
  63 pub unsafe fn __writeeflags(eflags: u64) {
  64     asm!("push {}", "popfq", in(reg) eflags, options(nomem, att_syntax));
  65 }
  66
  67 #[cfg(test)]
  68 mod tests {
  69     use crate::core_arch::x86::*;
  70
  71     #[test]
  72     #[allow(deprecated)]
  73     fn test_eflags() {
  74         unsafe {
  75             // reads eflags, writes them back, reads them again,
  76             // and compare for equality:
  77             let v = __readeflags();
  78             __writeeflags(v);
  79             let u = __readeflags();
  80             assert_eq!(v, u);
  81         }
  82     }
  83 }