diff options
| author | Julian Andres Klode <jak@debian.org> | 2016-09-27 18:28:55 +0200 |
|---|---|---|
| committer | Julian Andres Klode <jak@debian.org> | 2016-11-22 22:58:18 +0100 |
| commit | f903069c139df58d1ba855f7cf02c4a2d4e51dc3 (patch) | |
| tree | afeaaa1079fd67e99d7ab37f68eecb37988d5161 /apt-pkg/contrib | |
| parent | 7a3b00b10b6a5a740e07fc1b68a4f3fb3bcdac23 (diff) | |
Optimize VersionHash() to not need temporary copy of input
Stop copying stuff, and just parse the bytes one by-one to the
newly created AddCRC16Byte. This improves the instruction count
for an update run from 720,850,121 to 455,801,749 according to
callgrind.
Diffstat (limited to 'apt-pkg/contrib')
| -rw-r--r-- | apt-pkg/contrib/crc-16.cc | 4 | ||||
| -rw-r--r-- | apt-pkg/contrib/crc-16.h | 1 |
2 files changed, 5 insertions, 0 deletions
diff --git a/apt-pkg/contrib/crc-16.cc b/apt-pkg/contrib/crc-16.cc index f5df2d8b1..250d7664a 100644 --- a/apt-pkg/contrib/crc-16.cc +++ b/apt-pkg/contrib/crc-16.cc @@ -64,6 +64,10 @@ static unsigned short const crc16_table[256] = /* Recompute the FCS with one more character appended. */ #define CalcFCS(fcs, c) (((fcs) >> 8) ^ crc16_table[((fcs) ^ (c)) & 0xff]) +unsigned short AddCRC16Byte(unsigned short fcs, unsigned char byte) +{ + return CalcFCS(fcs, byte); +} unsigned short AddCRC16(unsigned short fcs, void const *Buf, unsigned long long len) { diff --git a/apt-pkg/contrib/crc-16.h b/apt-pkg/contrib/crc-16.h index 08acdafb7..6cc3556c6 100644 --- a/apt-pkg/contrib/crc-16.h +++ b/apt-pkg/contrib/crc-16.h @@ -13,6 +13,7 @@ #include <apt-pkg/macros.h> #define INIT_FCS 0xffff +unsigned short AddCRC16Byte(unsigned short fcs, unsigned char byte) APT_CONST; unsigned short AddCRC16(unsigned short fcs, void const *buf, unsigned long long len) APT_PURE; |