Update ion, update libc

libstd_real/libc/Cargo.toml

@@ -6,3 +6,4 @@ build = "build.rs"
 
 [dependencies]
 redox_syscall = { path = "../../syscall/" }
+spin = "*"

libstd_real/libc/src/funcs.rs

@@ -8,12 +8,33 @@ pub unsafe extern fn strlen(ptr: *const c_char) -> size_t {
     i
 }
 
+extern crate spin;
+use core::cell::Cell;
+use self::spin::Mutex;
+
+/// The randomness state.
+///
+/// This is updated when a new random integer is read.
+static STATE: Mutex<[u64; 2]> = Mutex::new([0xBADF00D1, 0xDEADBEEF]);
+
+/// Get a pseudorandom integer.
+///
+/// Note that this is full-cycle, so apply a modulo when true equidistribution is needed.
 pub unsafe extern fn random() -> u64 {
-    let rand;
+    // Fetch the state.
-    asm!("rdrand rax"
+    let mut state = STATE.lock();
-        : "={rax}"(rand)
+
-        :
+    // Store the first and second part.
-        :
+    let mut x = state[0];
-        : "intel", "volatile");
+    let y = state[1];
-    rand
+
+    // Put the second part into the first slot.
+    state[0] = y;
+    // Twist the first slot.
+    x ^= x << 23;
+    // Update the second slot.
+    state[1] = x ^ y ^ (x >> 17) ^ (y >> 26);
+
+    // Generate the final integer.
+    state[1].wrapping_add(y)
 }

libstd_real/libc/src/lib.rs

@@ -1,7 +1,9 @@
 #![no_std]
 #![allow(non_camel_case_types)]
 #![feature(asm)]
+#![feature(const_fn)]
 #![feature(naked_functions)]
+#![feature(thread_local)]
 
 #![cfg_attr(stdbuild, feature(no_std, core, core_slice_ext, staged_api, custom_attribute, cfg_target_vendor))]
 #![cfg_attr(stdbuild, no_std)]

programs/ion

@@ -1 +1 @@
-Subproject commit fad8108a164732ff63950b49ac78d76bb3834a87
+Subproject commit e594412a99c87daa619f09a673b288beecd275ca