A Small Start on SHA1 Performance Part II

The function k is a bit inefficient.

k n
   | (0 <= n)  &&amp;amp; (n <= 19) = 0x5a827999    
   | (20 <= n) && (n <= 39) = 0x6ed9eba1    
   | (40 <= n) && (n <= 59) = 0x8f1bbcdc    
   | (60 <= n) && (n <= 79) = 0xca62c1d6    
   | otherwise = error "invalid index for k" 

Since we know that n is always greater than or equal 0 and less than 80, we can use this.

k' n
   | n <= 19 = 0x5a827999    
   | n <= 39 = 0x6ed9eba1    
   | n <= 59 = 0x8f1bbcdc    
   | n <= 79 = 0xca62c1d6 

This gives a bit more of a saving.

     Sat Mar 10 13:49 2007 Time and Allocation Profiling Report  (Final)

        perfTest +RTS -p -RTS eg

     total time  =        9.55 secs   (191 ticks @ 50 ms)
     total alloc = 1,847,562,152 bytes  (excludes profiling overheads)

COST CENTRE                    MODULE               %time %alloc

oneBlock                       Data.Digest.SHA1      25.1   30.7
f                              Data.Digest.SHA1      16.2   11.7
$&                             Data.Digest.SHA1      14.7   17.3
rotL                           Data.Digest.SHA1      14.1   14.4
blockWord8sIn512               Data.Digest.SHA1       8.9    3.5
k'                             Data.Digest.SHA1       4.7    0.0
pad                            Data.Digest.SHA1       4.2    2.8
test2                          Main                   4.2    7.0
getWord32s'                    Data.Digest.SHA1       2.6    5.3
blockWord8sIn32                Data.Digest.SHA1       2.6    4.3
hash                           Data.Digest.SHA1       1.0    0.0
fromBytes                      Data.Digest.SHA1       1.0    2.8

We can do the same with f.

        Sat Mar 10 14:03 2007 Time and Allocation Profiling Report  (Final)

           perfTest +RTS -p -RTS eg

        total time  =        8.70 secs   (174 ticks @ 50 ms)
        total alloc = 1,722,554,056 bytes  (excludes profiling overheads)

COST CENTRE                    MODULE               %time %alloc

oneBlock                       Data.Digest.SHA1      29.3   32.9
rotL                           Data.Digest.SHA1      19.0   15.4
$&                             Data.Digest.SHA1      13.8   18.6
f'                             Data.Digest.SHA1      11.5    5.3
getWord32s'                    Data.Digest.SHA1       8.0    5.7
test2                          Main                   5.7    7.5
blockWord8sIn512               Data.Digest.SHA1       4.0    3.8
fromBytes                      Data.Digest.SHA1       2.9    3.0
k'                             Data.Digest.SHA1       2.3    0.0
pad                            Data.Digest.SHA1       1.7    3.0
blockWord8sIn32                Data.Digest.SHA1       1.7    4.6