>>>>> "Linus" == Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> writes:
Linus> On Mon, 2 Apr 2007, Peter Eriksen wrote:
Linus> #include <stdio.h>
Linus> #include <string.h>
Linus> int h2d(char c)
Linus> {
Linus> if ('a' <= c && c <= 'f')
Linus> return c-'a'+10;
Linus> else
Linus> return c-'0';
Linus> }
Linus> int lcprefix(char *a, char *b)
Linus> {
Linus> int bits = 0;
Linus> unsigned n1, n2;
Linus> while (*a == *b) {
Linus> bits += 4;
Linus> a++;
Linus> b++;
Linus> }
Linus> n1 = h2d(*a);
Linus> n2 = h2d(*b);
Linus> /* Would make more sense to start from bit 0.. */
Linus> while ((n1 & 8) == (n2 & 8)) {
Linus> bits++;
Linus> n1 <<= 1;
Linus> n2 <<= 1;
Linus> }
Linus> return bits;
Linus> }
Linus> int main(int argc, char **argv)
Linus> {
Linus> FILE *fp;
Linus> char old[41];
Linus> char cur[41];
Linus> int lcp = 0;
Linus> int table[64];
Linus> int i;
Linus> memset(table, 0, 64*sizeof(int));
Linus> memset(old, '0', 40);
Linus> old[40] = '\0';
Linus> fp = fopen(argv[1], "r");
Linus> fscanf(fp, "%s\n", cur);
Linus> if (lcp < lcprefix(old, cur)) {
Linus> lcp = lcprefix(old, cur);
Linus> }
Linus> table[lcp]++;
Linus> while (fscanf(fp, "%s\n", cur) != EOF) {
Linus> int newlcp = lcprefix(old, cur);
Linus> table[newlcp]++;
Linus> if (lcp < newlcp) {
Linus> printf("%s\n%s\n", old, cur);
Linus> lcp = newlcp;
Linus> printf("lcprefix = %d\n", newlcp);
Linus> }
Linus> memcpy(old, cur, 40);
Linus> }
Linus> for(i = 0; i < 64; i++) {
Linus> printf("%2d: %2d\n", i, table[i]);
Linus> }
Linus> return 0;
Linus> }
I don't have access to the linux-2.6 kernel, but on git.git at
d8b6a1a10b93666246984a50d64a163e71163aeb I get this:
$ git-rev-list --objects HEAD | sort | perl -lne '
substr($_, 40) = "";
($p ^ $_) =~ /^(\0*)/;
$count[length $1]++;
$p = $_;
END { print "$_: $count[$_]" for 0..$#count }
'
0: 16
1: 240
2: 3839
3: 24458
4: 8275
5: 619
6: 45
7:
8: 1
Yeay Perl. :)
--
Randal L. Schwartz - Stonehenge Consulting Services, Inc. - +1 503 777 0095
<merlyn@xxxxxxxxxxxxxx> <URL:http://www.stonehenge.com/merlyn/>
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