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| author | LemonBoy <thatlemon@gmail.com> | 2020-09-13 21:12:21 +0200 |
|---|---|---|
| committer | Andrew Kelley <andrew@ziglang.org> | 2020-09-13 16:32:21 -0400 |
| commit | 61e9e82bdc10110b74bdeb973cc542c7b73a4ae2 (patch) | |
| tree | f60c7e2f6b97395dee7602d90ce774f19e01e47e /lib/std | |
| parent | 5e50d145d964238a68d4780e253d26431e7c7994 (diff) | |
| download | zig-61e9e82bdc10110b74bdeb973cc542c7b73a4ae2.tar.gz zig-61e9e82bdc10110b74bdeb973cc542c7b73a4ae2.zip | |
std: Make the CRC32 calculation slightly faster
Speed up a little the slicing-by-8 code path by replacing the
(load+shift+xor)*4 sequence with a single u32 load plus a xor.
Before:
```
iterative: 1018 MiB/s [000000006c3b110d]
small keys: 1075 MiB/s [0035bf3dcac00000]
```
After:
```
iterative: 1114 MiB/s [000000006c3b110d]
small keys: 1324 MiB/s [0035bf3dcac00000]
```
Diffstat (limited to 'lib/std')
| -rw-r--r-- | lib/std/hash/crc.zig | 5 |
1 files changed, 1 insertions, 4 deletions
diff --git a/lib/std/hash/crc.zig b/lib/std/hash/crc.zig index 37695df8b3..6290369fca 100644 --- a/lib/std/hash/crc.zig +++ b/lib/std/hash/crc.zig @@ -71,10 +71,7 @@ pub fn Crc32WithPoly(comptime poly: Polynomial) type { const p = input[i .. i + 8]; // Unrolling this way gives ~50Mb/s increase - self.crc ^= (@as(u32, p[0]) << 0); - self.crc ^= (@as(u32, p[1]) << 8); - self.crc ^= (@as(u32, p[2]) << 16); - self.crc ^= (@as(u32, p[3]) << 24); + self.crc ^= std.mem.readIntLittle(u32, p[0..4]); self.crc = lookup_tables[0][p[7]] ^ |