Changeset 51879 in vbox for trunk/src/VBox/Runtime/common/checksum/alt-sha1.cpp

Timestamp:

Jul 5, 2014 10:51:29 PM (11 years ago)

Author:

vboxsync

svn:sync-xref-src-repo-rev:

94742

Message:

alt-sha1.cpp: Save an operation in both Ch() and Maj(). The Maj optimization is easier to figure out than the Ch() one.

File:

• trunk/src/VBox/Runtime/common/checksum/alt-sha1.cpp (modified) (2 diffs)

trunk/src/VBox/Runtime/common/checksum/alt-sha1.cpp

@@ -131 +131 @@
 DECL_FORCE_INLINE(uint32_t) rtSha1Ch(uint32_t uX, uint32_t uY, uint32_t uZ)
 {
+#if 1
+    /* Optimization that saves one operation and probably a temporary variable. */
+    uint32_t uResult = uY;
+    uResult ^= uZ;
+    uResult &= uX;
+    uResult ^= uZ;
+    return uResult;
+#else
+    /* The original. */
     uint32_t uResult = uX & uY;
     uResult ^= ~uX & uZ;
     return uResult;
+#endif
 }
 
@@ -150 +160 @@
 DECL_FORCE_INLINE(uint32_t) rtSha1Maj(uint32_t uX, uint32_t uY, uint32_t uZ)
 {
+#if 1
+    /* Optimization that save one operation and probably a temporary variable. */
+    uint32_t uResult = uY;
+    uResult ^= uZ;
+    uResult &= uX;
+    uResult ^= uY & uZ;
+    return uResult;
+#else
+    /* The original. */
     uint32_t uResult = (uX & uY);
     uResult |= (uX & uZ);
     uResult |= (uY & uZ);
     return uResult;
+#endif
 }