add support for no_std

Cargo.toml

@@ -32,3 +32,4 @@ cupid = "0.3"
 
 [features]
 strict = []
+std = []

ci/run.sh

@@ -19,3 +19,6 @@ echo "RUSTFLAGS=${RUSTFLAGS}"
 
 cargo test --target $TARGET --features "strict"
 cargo test --release --target $TARGET --features "strict"
+
+cargo test --target $TARGET --features "strict,std"
+cargo test --release --target $TARGET --features "strict,std"

src/lib.rs

@@ -128,6 +128,10 @@
                   cast_possible_truncation, cast_precision_loss,
                   shadow_reuse, cyclomatic_complexity, similar_names,
                   doc_markdown, many_single_char_names))]
+#![cfg_attr(not(feature = "std"), no_std)]
+
+#[cfg(not(feature = "std"))]
+extern crate core as std;
 
 #[cfg(test)]
 extern crate stdsimd_test;

src/x86/mod.rs

@@ -41,3 +41,14 @@ mod abm;
 mod bmi;
 mod bmi2;
 mod tbm;
+
+#[allow(non_camel_case_types)]
+#[cfg(not(feature = "std"))]
+#[repr(u8)]
+pub enum c_void {
+    #[doc(hidden)] __variant1,
+    #[doc(hidden)] __variant2,
+}
+
+#[cfg(feature = "std")]
+use std::os::raw::c_void;

src/x86/runtime.rs

@@ -283,6 +283,7 @@ pub fn __unstable_detect_feature(x: __Feature) -> bool {
 
 #[cfg(test)]
 mod tests {
+    #[cfg(feature = "std")]
     #[test]
     fn runtime_detection_x86_nocapture() {
         println!("sse: {:?}", cfg_feature_enabled!("sse"));

src/x86/sse.rs

@@ -3,7 +3,7 @@
 use simd_llvm::simd_shuffle4;
 use v128::*;
 use v64::f32x2;
-use std::os::raw::c_void;
+use super::c_void;
 use std::mem;
 use std::ptr;
 

src/x86/sse2.rs

@@ -4,7 +4,7 @@
 use stdsimd_test::assert_instr;
 
 use std::mem;
-use std::os::raw::c_void;
+use super::c_void;
 use std::ptr;
 
 use simd_llvm::{simd_cast, simd_shuffle16, simd_shuffle2, simd_shuffle4,
@@ -2242,7 +2242,7 @@ extern "C" {
 
 #[cfg(test)]
 mod tests {
-    use std::os::raw::c_void;
+    use super::c_void;
     use stdsimd_test::simd_test;
     use test::black_box; // Used to inhibit constant-folding.