From: Jonathan Dieter <jdieter@gmail.com>
Date: Thu, 3 May 2018 08:00:11 +0000 (+0300)
Subject: Buzhash integration into zck and some small changes to make buzhash work
X-Git-Tag: archive/raspbian/1.1.9+ds1-1+rpi1~1^2~295
X-Git-Url: https://dgit.raspbian.org/?a=commitdiff_plain;h=800c0914227ea996202649b1441357909d0b3ffc;p=zchunk.git

Buzhash integration into zck and some small changes to make buzhash work
correctly

Signed-off-by: Jonathan Dieter <jdieter@gmail.com>
---

diff --git a/src/buzhash/buzhash.c b/src/buzhash/buzhash.c
index f3da669..7806271 100644
--- a/src/buzhash/buzhash.c
+++ b/src/buzhash/buzhash.c
@@ -1,8 +1,32 @@
+/*
+ * Copyright (c) 2015, the urlblock developers.
+ * Copyright (c) 2018 Jonathan Dieter <jdieter@gmail.com>
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+y
 #include "buzhash.h"
-#include "util.h"
 
 #include <string.h>
 
+#define rol32(v,s) (((v) << (s)) | ((v) >> (32 - (s))))
+
 const uint32_t buzhash_table[] = {
   0x458be752, 0xc10748cc, 0xfbbcdbb8, 0x6ded5b68,
   0xb10a82b5, 0x20d75648, 0xdfc5665f, 0xa8428801,
@@ -70,7 +94,7 @@ const uint32_t buzhash_table[] = {
   0x7bf7cabc, 0xf9c18d66, 0x593ade65, 0xd95ddf11,
 };
 
-const size_t buzhash_width = 4;
+const size_t buzhash_width = 4096;
 
 uint32_t
 buzhash (const char *s)
@@ -87,5 +111,5 @@ buzhash (const char *s)
 uint32_t
 buzhash_update (const char *s, uint32_t h)
 {
-  return rol32 (h, 1) ^ rol32 (buzhash_table[(size_t) s[0]], buzhash_width) ^ buzhash_table[(size_t) s[buzhash_width]];
+  return rol32 (h, 1) ^ rol32 (buzhash_table[(size_t) (s-buzhash_width)[0]], buzhash_width) ^ buzhash_table[(size_t) s[0]];
 }
diff --git a/src/zck.c b/src/zck.c
index 7594d76..3d2a7f0 100644
--- a/src/zck.c
+++ b/src/zck.c
@@ -34,11 +34,9 @@
 #include <unistd.h>
 #include <zck.h>
 
+#include "buzhash/buzhash.h"
 #include "memmem.h"
 
-#define WINDOW_SIZE 4096
-#define MATCH_SUM WINDOW_SIZE-1
-
 int main (int argc, char *argv[]) {
     char *out_name;
     char *dict = NULL;
@@ -134,7 +132,7 @@ int main (int argc, char *argv[]) {
         close(in_fd);
 
         /* Chunk based on string in argv[2] (Currently with ugly hack to group srpms together) */
-        if(True) {
+        if(False) {
             char *found = data;
             char *search = found;
             char *prev_srpm = memmem(search, in_size - (search-data), "<rpm:sourcerpm", 14);
@@ -185,28 +183,23 @@ int main (int argc, char *argv[]) {
                     search = NULL;
                 }
             }
-        /* Naive (and inefficient) rolling window */
+        /* Buzhash rolling window */
         } else {
             char *cur_loc = data;
             char *start = data;
             char *window_loc;
-            int window_sum;
 
             while(cur_loc < data + in_size) {
-                window_sum = 0;
+                uint32_t bh = 0;
                 window_loc = cur_loc;
-                if(cur_loc + WINDOW_SIZE < data + in_size) {
-                    for(int i=0; i<WINDOW_SIZE; i++) {
-                        window_sum += cur_loc[i];
-                    }
-                    cur_loc += WINDOW_SIZE;
+                if(cur_loc + buzhash_width < data + in_size) {
+                    bh = buzhash(window_loc);
+                    cur_loc += buzhash_width;
                     while(cur_loc < data + in_size) {
-                        window_sum += cur_loc[0];
-                        window_sum -= window_loc[0];
-                        cur_loc++;
-                        window_loc++;
-                        if(((window_sum) & (WINDOW_SIZE - 1)) == 0)
+                        bh = buzhash_update(cur_loc, bh);
+                        if(((bh) & (8192 - 1)) == 0)
                             break;
+                        cur_loc++;
                     }
                 } else {
                     cur_loc = data + in_size;