float: Add crate for float.h

Add a crate with stubbed functions for the float.h header.

src/float/Cargo.toml

@@ -0,0 +1,11 @@
+[package]
+name = "float"
+version = "0.1.0"
+authors = ["Dan Robertson <danlrobertson89@gmail.com>"]
+
+[build-dependencies]
+cbindgen = { path = "../../cbindgen" }
+
+[dependencies]
+platform = { path = "../platform" }
+fenv = { path = "../fenv" }

src/float/build.rs

@@ -0,0 +1,11 @@
+extern crate cbindgen;
+
+use std::{env, fs};
+
+fn main() {
+    let crate_dir = env::var("CARGO_MANIFEST_DIR").expect("CARGO_MANIFEST_DIR not set");
+    fs::create_dir_all("../../target/include").expect("failed to create include directory");
+    cbindgen::generate(crate_dir)
+        .expect("failed to generate bindings")
+        .write_to_file("../../target/include/float.h");
+}

src/float/cbindgen.toml

@@ -0,0 +1,6 @@
+sys_includes = ["sys/types.h", "bits/float.h"]
+include_guard = "_FLOAT_H"
+language = "C"
+
+[enum]
+prefix_with_name = true

src/float/src/lib.rs

@@ -0,0 +1,19 @@
+//! float.h implementation for Redox, following
+//! http://pubs.opengroup.org/onlinepubs/7908799/xsh/float.h.html
+
+#![no_std]
+
+extern crate fenv;
+extern crate platform;
+
+use platform::types::*;
+use fenv::{fegetround, FE_TONEAREST};
+
+pub const FLT_RADIX: c_int = 2;
+
+pub unsafe extern "C" fn flt_rounds() -> c_int {
+    match fegetround() {
+        FE_TONEAREST => 1,
+        _ => -1,
+    }
+}