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Merge branch 'np/delta' into next

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* np/delta:
  improve diff-delta with sparse and/or repetitive data
  tiny optimization to diff-delta
This commit is contained in:
Junio C Hamano
2006-05-02 21:56:29 -07:00
parent 9d275ed3e3 06a9f92035
commit 9f6532dd65
1 changed files with 29 additions and 16 deletions
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45
diff-delta.c
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@@ -136,11 +136,12 @@ struct delta_index {
struct delta_index * create_delta_index(const void *buf, unsigned long bufsize)
{
unsigned int i, hsize, hmask, entries, *hash_count;
unsigned int i, hsize, hmask, entries, prev_val, *hash_count;
const unsigned char *data, *buffer = buf;
struct delta_index *index;
struct index_entry *entry, **hash;
void *mem;
unsigned long memsize;
if (!buf || !bufsize)
return NULL;
@@ -155,9 +156,10 @@ struct delta_index * create_delta_index(const void *buf, unsigned long bufsize)
hmask = hsize - 1;
/* allocate lookup index */
mem = malloc(sizeof(*index) +
sizeof(*hash) * hsize +
sizeof(*entry) * entries);
memsize = sizeof(*index) +
sizeof(*hash) * hsize +
sizeof(*entry) * entries;
mem = malloc(memsize);
if (!mem)
return NULL;
index = mem;
@@ -179,18 +181,26 @@ struct delta_index * create_delta_index(const void *buf, unsigned long bufsize)
}
/* then populate the index */
data = buffer + entries * RABIN_WINDOW - RABIN_WINDOW;
while (data >= buffer) {
prev_val = ~0;
for (data = buffer + entries * RABIN_WINDOW - RABIN_WINDOW;
data >= buffer;
data -= RABIN_WINDOW) {
unsigned int val = 0;
for (i = 1; i <= RABIN_WINDOW; i++)
val = ((val << 8) | data[i]) ^ T[val >> RABIN_SHIFT];
i = val & hmask;
entry->ptr = data + RABIN_WINDOW;
entry->val = val;
entry->next = hash[i];
hash[i] = entry++;
hash_count[i]++;
data -= RABIN_WINDOW;
if (val == prev_val) {
/* keep the lowest of consecutive identical blocks */
entry[-1].ptr = data + RABIN_WINDOW;
} else {
prev_val = val;
i = val & hmask;
entry->ptr = data + RABIN_WINDOW;
entry->val = val;
entry->next = hash[i];
hash[i] = entry++;
hash_count[i]++;
entries--;
}
}
/*
@@ -220,6 +230,10 @@ struct delta_index * create_delta_index(const void *buf, unsigned long bufsize)
}
free(hash_count);
/* If we didn't use all hash entries, free the unused memory. */
if (entries)
index = realloc(index, memsize - entries * sizeof(*entry));
return index;
}
@@ -239,7 +253,7 @@ create_delta(const struct delta_index *index,
const void *trg_buf, unsigned long trg_size,
unsigned long *delta_size, unsigned long max_size)
{
unsigned int i, outpos, outsize, hash_mask, val;
unsigned int i, outpos, outsize, val;
int inscnt;
const unsigned char *ref_data, *ref_top, *data, *top;
unsigned char *out;
@@ -275,7 +289,6 @@ create_delta(const struct delta_index *index,
ref_top = ref_data + index->src_size;
data = trg_buf;
top = trg_buf + trg_size;
hash_mask = index->hash_mask;
outpos++;
val = 0;
@@ -290,7 +303,7 @@ create_delta(const struct delta_index *index,
struct index_entry *entry;
val ^= U[data[-RABIN_WINDOW]];
val = ((val << 8) | *data) ^ T[val >> RABIN_SHIFT];
i = val & hash_mask;
i = val & index->hash_mask;
for (entry = index->hash[i]; entry; entry = entry->next) {
const unsigned char *ref = entry->ptr;
const unsigned char *src = data;