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src/backup/chunker.rs: use 64 byte chunker window size

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This results in faster code.
This commit is contained in:
Dietmar Maurer 2019-02-19 12:27:37 +01:00
parent 9a3e869cf5
commit cd1598302a
1 changed files with 8 additions and 5 deletions
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13
src/backup/chunker.rs
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@ -1,4 +1,4 @@
const CA_CHUNKER_WINDOW_SIZE: usize = 48; const CA_CHUNKER_WINDOW_SIZE: usize = 64;
/// Slinding window chunker (Buzhash) /// Slinding window chunker (Buzhash)
/// ///
@ -161,14 +161,16 @@ impl Chunker {
self.start(); self.start();
} }
let mut idx = self.chunk_size % CA_CHUNKER_WINDOW_SIZE; //let mut idx = self.chunk_size % CA_CHUNKER_WINDOW_SIZE;
let mut idx = self.chunk_size & 0x3f;
while pos < data_len { while pos < data_len {
// roll window // roll window
let enter = data[pos]; let enter = data[pos];
let leave = self.window[idx]; let leave = self.window[idx];
self.h = self.h.rotate_left(1) ^ self.h = self.h.rotate_left(1) ^
BUZHASH_TABLE[leave as usize].rotate_left(CA_CHUNKER_WINDOW_SIZE as u32) ^ //BUZHASH_TABLE[leave as usize].rotate_left(CA_CHUNKER_WINDOW_SIZE as u32) ^
BUZHASH_TABLE[leave as usize] ^
BUZHASH_TABLE[enter as usize]; BUZHASH_TABLE[enter as usize];
self.chunk_size += 1; self.chunk_size += 1;
@ -183,7 +185,8 @@ impl Chunker {
return pos; return pos;
} }
idx = self.chunk_size % CA_CHUNKER_WINDOW_SIZE; //idx = self.chunk_size % CA_CHUNKER_WINDOW_SIZE;
idx = self.chunk_size & 0x3f;
//idx += 1; if idx >= CA_CHUNKER_WINDOW_SIZE { idx = 0 }; //idx += 1; if idx >= CA_CHUNKER_WINDOW_SIZE { idx = 0 };
} }
@ -191,7 +194,7 @@ impl Chunker {
} }
// fast implementation avoiding modulo // fast implementation avoiding modulo
#[inline(always)] // #[inline(always)]
fn shall_break(&self) -> bool { fn shall_break(&self) -> bool {
if self.chunk_size >= self.chunk_size_max { return true; } if self.chunk_size >= self.chunk_size_max { return true; }