capsules_extra::isolated_nonvolatile_storage_driver

Function usize32s_to_usize

Source 
pub const fn usize32s_to_usize(lo: usize, hi: usize) -> usize
Expand description

Helper function to convert create a full, single usize value from two 32-bit values stored in usizes.

In C this would look like:

size_t v = (hi << 32) | (uint32_t) lo;

This is useful when passing a machine-sized value (i.e. a size_t) via the system call interface in two 32-bit usize values. On a 32-bit machine this essentially has no effect; the full value is stored in the lo usize. On a 64-bit machine, this creates a usize by concatenating the hi and lo 32-bit values.

§TODO

This can be more succinctly implemented using unbounded_shl(). However, that method is currently a nightly-only feature.