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correctness

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Lokathor 2018-11-14 20:14:36 -07:00
parent 19a766a345
commit cb5d856e00
1 changed files with 11 additions and 16 deletions
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27
src/core_extras.rs
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@ -1,11 +1,13 @@
//! Things that I wish were in core, but aren't.
/// A simple wrapper to any `*mut T` so that the basic "read" and "write"
/// operations are volatile.
/// A simple wrapper for any `*mut T` to adjust the basic operations.
///
/// Accessing the GBA's IO registers and video ram and specific other places on
/// **must** be done with volatile operations. Having this wrapper makes that
/// more clear for all the const value IO registers.
/// Read and Write are made to be volatile. Offset is made to be
/// wrapping_offset. This makes it much easier to correctly work with IO
/// Registers and all display related memory on the GBA.
///
/// As a bonus, use of this type is mostly `cargo test` safe. Reads will return
/// a `zeroed()` value instead, and writes will do nothing.
#[derive(Debug, Clone, Copy, Hash, PartialEq, Eq, PartialOrd, Ord)]
#[repr(transparent)]
pub struct VolatilePtr<T>(pub *mut T);
@ -52,20 +54,13 @@ impl<T> VolatilePtr<T> {
}
}
/// Offsets this address by the amount given.
/// Performs a wrapping_offset by the number of slots given to a new position.
///
/// # Safety
///
/// This is a standard offset, so all safety concerns of a normal raw pointer
/// offset apply.
/// This is a wrapping_offset, so all safety concerns of a normal raw pointer
/// wrapping_offset apply.
pub unsafe fn offset(self, count: isize) -> Self {
#[cfg(not(test))]
{
VolatilePtr(self.0.offset(count))
}
#[cfg(test)]
{
VolatilePtr(self.0.wrapping_offset(count))
}
VolatilePtr(self.0.wrapping_offset(count))
}
}