Move XBZRLE encoding code to a separate file to allow testing

Signed-off-by: Orit Wasserman <owasserm@redhat.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>

Signed-off-by: Juan Quintela <quintela@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>

3 files changed, 174 insertions, 160 deletions

diff --git a/Makefile.objs b/Makefile.objs
index 68eb0cef1a..21e9c911f5 100644
--- a/Makefile.objs
+++ b/Makefile.objs
@@ -59,7 +59,7 @@ common-obj-$(CONFIG_LINUX) += fsdev/
 common-obj-y += migration.o migration-tcp.o
 common-obj-y += qemu-char.o #aio.o
 common-obj-y += block-migration.o
-common-obj-y += page_cache.o
+common-obj-y += page_cache.o xbzrle.o
 
 common-obj-$(CONFIG_POSIX) += migration-exec.o migration-unix.o migration-fd.o
 
diff --git a/savevm.c b/savevm.c
index 304d1effe5..b947e6a303 100644
--- a/savevm.c
+++ b/savevm.c
@@ -2388,162 +2388,3 @@ void vmstate_register_ram_global(MemoryRegion *mr)
 {
     vmstate_register_ram(mr, NULL);
 }
-
-/*
-  page = zrun nzrun
-       | zrun nzrun page
-
-  zrun = length
-
-  nzrun = length byte...
-
-  length = uleb128 encoded integer
- */
-int xbzrle_encode_buffer(uint8_t *old_buf, uint8_t *new_buf, int slen,
-                         uint8_t *dst, int dlen)
-{
-    uint32_t zrun_len = 0, nzrun_len = 0;
-    int d = 0, i = 0;
-    long res, xor;
-    uint8_t *nzrun_start = NULL;
-
-    g_assert(!(((uintptr_t)old_buf | (uintptr_t)new_buf | slen) %
-               sizeof(long)));
-
-    while (i < slen) {
-        /* overflow */
-        if (d + 2 > dlen) {
-            return -1;
-        }
-
-        /* not aligned to sizeof(long) */
-        res = (slen - i) % sizeof(long);
-        while (res && old_buf[i] == new_buf[i]) {
-            zrun_len++;
-            i++;
-            res--;
-        }
-
-        /* word at a time for speed */
-        if (!res) {
-            while (i < slen &&
-                   (*(long *)(old_buf + i)) == (*(long *)(new_buf + i))) {
-                i += sizeof(long);
-                zrun_len += sizeof(long);
-            }
-
-            /* go over the rest */
-            while (i < slen && old_buf[i] == new_buf[i]) {
-                zrun_len++;
-                i++;
-            }
-        }
-
-        /* buffer unchanged */
-        if (zrun_len == slen) {
-            return 0;
-        }
-
-        /* skip last zero run */
-        if (i == slen) {
-            return d;
-        }
-
-        d += uleb128_encode_small(dst + d, zrun_len);
-
-        zrun_len = 0;
-        nzrun_start = new_buf + i;
-
-        /* overflow */
-        if (d + 2 > dlen) {
-            return -1;
-        }
-        /* not aligned to sizeof(long) */
-        res = (slen - i) % sizeof(long);
-        while (res && old_buf[i] != new_buf[i]) {
-            i++;
-            nzrun_len++;
-            res--;
-        }
-
-        /* word at a time for speed, use of 32-bit long okay */
-        if (!res) {
-            /* truncation to 32-bit long okay */
-            long mask = (long)0x0101010101010101ULL;
-            while (i < slen) {
-                xor = *(long *)(old_buf + i) ^ *(long *)(new_buf + i);
-                if ((xor - mask) & ~xor & (mask << 7)) {
-                    /* found the end of an nzrun within the current long */
-                    while (old_buf[i] != new_buf[i]) {
-                        nzrun_len++;
-                        i++;
-                    }
-                    break;
-                } else {
-                    i += sizeof(long);
-                    nzrun_len += sizeof(long);
-                }
-            }
-        }
-
-        d += uleb128_encode_small(dst + d, nzrun_len);
-        /* overflow */
-        if (d + nzrun_len > dlen) {
-            return -1;
-        }
-        memcpy(dst + d, nzrun_start, nzrun_len);
-        d += nzrun_len;
-        nzrun_len = 0;
-    }
-
-    return d;
-}
-
-int xbzrle_decode_buffer(uint8_t *src, int slen, uint8_t *dst, int dlen)
-{
-    int i = 0, d = 0;
-    int ret;
-    uint32_t count = 0;
-
-    while (i < slen) {
-
-        /* zrun */
-        if ((slen - i) < 2) {
-            return -1;
-        }
-
-        ret = uleb128_decode_small(src + i, &count);
-        if (ret < 0 || (i && !count)) {
-            return -1;
-        }
-        i += ret;
-        d += count;
-
-        /* overflow */
-        if (d > dlen) {
-            return -1;
-        }
-
-        /* nzrun */
-        if ((slen - i) < 2) {
-            return -1;
-        }
-
-        ret = uleb128_decode_small(src + i, &count);
-        if (ret < 0 || !count) {
-            return -1;
-        }
-        i += ret;
-
-        /* overflow */
-        if (d + count > dlen || i + count > slen) {
-            return -1;
-        }
-
-        memcpy(dst + d, src + i, count);
-        d += count;
-        i += count;
-    }
-
-    return d;
-}
diff --git a/xbzrle.c b/xbzrle.c
new file mode 100644
index 0000000000..fbcb35d0e3
--- /dev/null
+++ b/xbzrle.c
@@ -0,0 +1,173 @@
+/*
+ * Xor Based Zero Run Length Encoding
+ *
+ * Copyright 2013 Red Hat, Inc. and/or its affiliates
+ *
+ * Authors:
+ *  Orit Wasserman  <owasserm@redhat.com>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or later.
+ * See the COPYING file in the top-level directory.
+ *
+ */
+#include "qemu-common.h"
+#include "include/migration/migration.h"
+
+/*
+  page = zrun nzrun
+       | zrun nzrun page
+
+  zrun = length
+
+  nzrun = length byte...
+
+  length = uleb128 encoded integer
+ */
+int xbzrle_encode_buffer(uint8_t *old_buf, uint8_t *new_buf, int slen,
+                         uint8_t *dst, int dlen)
+{
+    uint32_t zrun_len = 0, nzrun_len = 0;
+    int d = 0, i = 0;
+    long res, xor;
+    uint8_t *nzrun_start = NULL;
+
+    g_assert(!(((uintptr_t)old_buf | (uintptr_t)new_buf | slen) %
+               sizeof(long)));
+
+    while (i < slen) {
+        /* overflow */
+        if (d + 2 > dlen) {
+            return -1;
+        }
+
+        /* not aligned to sizeof(long) */
+        res = (slen - i) % sizeof(long);
+        while (res && old_buf[i] == new_buf[i]) {
+            zrun_len++;
+            i++;
+            res--;
+        }
+
+        /* word at a time for speed */
+        if (!res) {
+            while (i < slen &&
+                   (*(long *)(old_buf + i)) == (*(long *)(new_buf + i))) {
+                i += sizeof(long);
+                zrun_len += sizeof(long);
+            }
+
+            /* go over the rest */
+            while (i < slen && old_buf[i] == new_buf[i]) {
+                zrun_len++;
+                i++;
+            }
+        }
+
+        /* buffer unchanged */
+        if (zrun_len == slen) {
+            return 0;
+        }
+
+        /* skip last zero run */
+        if (i == slen) {
+            return d;
+        }
+
+        d += uleb128_encode_small(dst + d, zrun_len);
+
+        zrun_len = 0;
+        nzrun_start = new_buf + i;
+
+        /* overflow */
+        if (d + 2 > dlen) {
+            return -1;
+        }
+        /* not aligned to sizeof(long) */
+        res = (slen - i) % sizeof(long);
+        while (res && old_buf[i] != new_buf[i]) {
+            i++;
+            nzrun_len++;
+            res--;
+        }
+
+        /* word at a time for speed, use of 32-bit long okay */
+        if (!res) {
+            /* truncation to 32-bit long okay */
+            long mask = (long)0x0101010101010101ULL;
+            while (i < slen) {
+                xor = *(long *)(old_buf + i) ^ *(long *)(new_buf + i);
+                if ((xor - mask) & ~xor & (mask << 7)) {
+                    /* found the end of an nzrun within the current long */
+                    while (old_buf[i] != new_buf[i]) {
+                        nzrun_len++;
+                        i++;
+                    }
+                    break;
+                } else {
+                    i += sizeof(long);
+                    nzrun_len += sizeof(long);
+                }
+            }
+        }
+
+        d += uleb128_encode_small(dst + d, nzrun_len);
+        /* overflow */
+        if (d + nzrun_len > dlen) {
+            return -1;
+        }
+        memcpy(dst + d, nzrun_start, nzrun_len);
+        d += nzrun_len;
+        nzrun_len = 0;
+    }
+
+    return d;
+}
+
+int xbzrle_decode_buffer(uint8_t *src, int slen, uint8_t *dst, int dlen)
+{
+    int i = 0, d = 0;
+    int ret;
+    uint32_t count = 0;
+
+    while (i < slen) {
+
+        /* zrun */
+        if ((slen - i) < 2) {
+            return -1;
+        }
+
+        ret = uleb128_decode_small(src + i, &count);
+        if (ret < 0 || (i && !count)) {
+            return -1;
+        }
+        i += ret;
+        d += count;
+
+        /* overflow */
+        if (d > dlen) {
+            return -1;
+        }
+
+        /* nzrun */
+        if ((slen - i) < 2) {
+            return -1;
+        }
+
+        ret = uleb128_decode_small(src + i, &count);
+        if (ret < 0 || !count) {
+            return -1;
+        }
+        i += ret;
+
+        /* overflow */
+        if (d + count > dlen || i + count > slen) {
+            return -1;
+        }
+
+        memcpy(dst + d, src + i, count);
+        d += count;
+        i += count;
+    }
+
+    return d;
+}