diff options
Diffstat (limited to 'diffcore-delta.c')
| -rw-r--r-- | diffcore-delta.c | 39 |
1 files changed, 22 insertions, 17 deletions
diff --git a/diffcore-delta.c b/diffcore-delta.c index 7338a40c5..a038b166c 100644 --- a/diffcore-delta.c +++ b/diffcore-delta.c @@ -5,23 +5,20 @@ /* * Idea here is very simple. * - * We have total of (sz-N+1) N-byte overlapping sequences in buf whose - * size is sz. If the same N-byte sequence appears in both source and - * destination, we say the byte that starts that sequence is shared - * between them (i.e. copied from source to destination). + * Almost all data we are interested in are text, but sometimes we have + * to deal with binary data. So we cut them into chunks delimited by + * LF byte, or 64-byte sequence, whichever comes first, and hash them. * - * For each possible N-byte sequence, if the source buffer has more - * instances of it than the destination buffer, that means the - * difference are the number of bytes not copied from source to - * destination. If the counts are the same, everything was copied - * from source to destination. If the destination has more, - * everything was copied, and destination added more. + * For those chunks, if the source buffer has more instances of it + * than the destination buffer, that means the difference are the + * number of bytes not copied from source to destination. If the + * counts are the same, everything was copied from source to + * destination. If the destination has more, everything was copied, + * and destination added more. * * We are doing an approximation so we do not really have to waste * memory by actually storing the sequence. We just hash them into * somewhere around 2^16 hashbuckets and count the occurrences. - * - * The length of the sequence is arbitrarily set to 8 for now. */ /* Wild guess at the initial hash size */ @@ -125,11 +122,14 @@ static struct spanhash_top *add_spanhash(struct spanhash_top *top, } } -static struct spanhash_top *hash_chars(unsigned char *buf, unsigned int sz) +static struct spanhash_top *hash_chars(struct diff_filespec *one) { int i, n; unsigned int accum1, accum2, hashval; struct spanhash_top *hash; + unsigned char *buf = one->data; + unsigned int sz = one->size; + int is_text = !one->is_binary; i = INITIAL_HASH_SIZE; hash = xmalloc(sizeof(*hash) + sizeof(struct spanhash) * (1<<i)); @@ -143,6 +143,11 @@ static struct spanhash_top *hash_chars(unsigned char *buf, unsigned int sz) unsigned int c = *buf++; unsigned int old_1 = accum1; sz--; + + /* Ignore CR in CRLF sequence if text */ + if (is_text && c == '\r' && sz && *buf == '\n') + continue; + accum1 = (accum1 << 7) ^ (accum2 >> 25); accum2 = (accum2 << 7) ^ (old_1 >> 25); accum1 += c; @@ -156,8 +161,8 @@ static struct spanhash_top *hash_chars(unsigned char *buf, unsigned int sz) return hash; } -int diffcore_count_changes(void *src, unsigned long src_size, - void *dst, unsigned long dst_size, +int diffcore_count_changes(struct diff_filespec *src, + struct diff_filespec *dst, void **src_count_p, void **dst_count_p, unsigned long delta_limit, @@ -172,14 +177,14 @@ int diffcore_count_changes(void *src, unsigned long src_size, if (src_count_p) src_count = *src_count_p; if (!src_count) { - src_count = hash_chars(src, src_size); + src_count = hash_chars(src); if (src_count_p) *src_count_p = src_count; } if (dst_count_p) dst_count = *dst_count_p; if (!dst_count) { - dst_count = hash_chars(dst, dst_size); + dst_count = hash_chars(dst); if (dst_count_p) *dst_count_p = dst_count; } |