Auto merge of #13 - schodet:stdio, r=japaric

Stdio fixes after review

See #11.

src/hio.rs

@@ -41,6 +41,10 @@ impl fmt::Write for HStdout {
 
 /// Construct a new handle to the host's standard error.
 pub fn hstderr() -> Result<HStderr, ()> {
+    // There is actually no stderr access in ARM Semihosting documentation. Use
+    // convention used in libgloss.
+    // See: libgloss/arm/syscalls.c, line 139.
+    // https://sourceware.org/git/gitweb.cgi?p=newlib-cygwin.git;a=blob;f=libgloss/arm/syscalls.c#l139
     open(":tt\0", nr::open::W_APPEND).map(|fd| HStderr { fd })
 }
 

src/lib.rs

@@ -14,9 +14,6 @@
 //! [sc]: https://en.wikipedia.org/wiki/System_call
 //! [`sc`]: https://crates.io/crates/sc
 //!
-//! And since the most used semihosting operation is writing to the host's
-//! stdout, convenience `hprint` and `hprintln` macros are provided.
-//!
 //! # Forewarning
 //!
 //! Semihosting operations are *very* slow. Like, each WRITE operation can take
@@ -39,9 +36,6 @@
 //!
 //!     // Signature: fn write(fd: usize, ptr: *const u8, len: usize) -> usize
 //!     let r = unsafe { syscall!(WRITE, STDOUT, MSG.as_ptr(), MSG.len()) };
-//!
-//!     // (Or you could have just written `hprintln!("Hello, world!")`)
-//!     // ..
 //! }
 //! ```
 //!

src/nr.rs

@@ -28,17 +28,30 @@ pub const WRITEC: usize = 0x03;
 pub const ENTER_SVC: usize = 0x17;
 pub const REPORT_EXCEPTION: usize = 0x18;
 
+/// Values for the mode parameter of the OPEN syscall.
 pub mod open {
+    /// Mode corresponding to fopen "r" mode.
     pub const R: usize = 0;
-    pub const R_TEXT: usize = 1;
+    /// Mode corresponding to fopen "rb" mode.
+    pub const R_BINARY: usize = 1;
+    /// Mode corresponding to fopen "r+" mode.
     pub const RW: usize = 2;
-    pub const RW_TEXT: usize = 3;
+    /// Mode corresponding to fopen "r+b" mode.
+    pub const RW_BINARY: usize = 3;
+    /// Mode corresponding to fopen "w" mode.
     pub const W_TRUNC: usize = 4;
-    pub const W_TRUNC_TEXT: usize = 5;
+    /// Mode corresponding to fopen "wb" mode.
+    pub const W_TRUNC_BINARY: usize = 5;
+    /// Mode corresponding to fopen "w+" mode.
     pub const RW_TRUNC: usize = 6;
-    pub const RW_TRUNC_TEXT: usize = 7;
+    /// Mode corresponding to fopen "w+b" mode.
+    pub const RW_TRUNC_BINARY: usize = 7;
+    /// Mode corresponding to fopen "a" mode.
     pub const W_APPEND: usize = 8;
-    pub const W_APPEND_TEXT: usize = 9;
+    /// Mode corresponding to fopen "ab" mode.
+    pub const W_APPEND_BINARY: usize = 9;
+    /// Mode corresponding to fopen "a+" mode.
     pub const RW_APPEND: usize = 10;
-    pub const RW_APPEND_TEXT: usize = 11;
+    /// Mode corresponding to fopen "a+b" mode.
+    pub const RW_APPEND_BINARY: usize = 11;
 }