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| author | Huon Wilson <dbau.pp+github@gmail.com> | 2013-10-09 02:13:34 +1100 |
|---|---|---|
| committer | Huon Wilson <dbau.pp+github@gmail.com> | 2013-10-09 22:22:43 +1100 |
| commit | 649c1759e8b56f0ac31dd31e46eae81b7ffd1e2c (patch) | |
| tree | bd5b0f0fb2920d4e9f120705cfba5b5ef7af7c59 /src/libstd/rand/reader.rs | |
| parent | 38732c4b5cf778cb1b441bfc4290b3e3524b80c2 (diff) | |
| download | rust-649c1759e8b56f0ac31dd31e46eae81b7ffd1e2c.tar.gz rust-649c1759e8b56f0ac31dd31e46eae81b7ffd1e2c.zip | |
std::rand::reader: describe cfg!(endianness).
Diffstat (limited to 'src/libstd/rand/reader.rs')
| -rw-r--r-- | src/libstd/rand/reader.rs | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/src/libstd/rand/reader.rs b/src/libstd/rand/reader.rs index 78dad30117d..961a5b2cd28 100644 --- a/src/libstd/rand/reader.rs +++ b/src/libstd/rand/reader.rs @@ -47,6 +47,9 @@ impl<R: Reader> ReaderRng<R> { impl<R: Reader> Rng for ReaderRng<R> { fn next_u32(&mut self) -> u32 { + // This is designed for speed: reading a LE integer on a LE + // platform just involves blitting the bytes into the memory + // of the u32, similarly for BE on BE; avoiding byteswapping. if cfg!(target_endian="little") { self.reader.read_le_u32_() } else { @@ -54,6 +57,7 @@ impl<R: Reader> Rng for ReaderRng<R> { } } fn next_u64(&mut self) -> u64 { + // see above for explanation. if cfg!(target_endian="little") { self.reader.read_le_u64_() } else { |