Changeset 262 for trunk/poppler/freetype2/src/base/ftcalc.c

Timestamp:

Jan 17, 2009, 10:45:05 AM (12 years ago)

Author:

Eugene Romanenko

Message:

PDF plugin: freetype library updated to version 2.3.8

File:

• trunk/poppler/freetype2/src/base/ftcalc.c (modified) (4 diffs)

trunk/poppler/freetype2/src/base/ftcalc.c

@@ -39 +39 @@
 #include FT_INTERNAL_OBJECTS_H
 
+#ifdef FT_MULFIX_INLINED
+#undef FT_MulFix
+#endif
 
 /* we need to define a 64-bits data type here */
@@ -194 +197 @@
              FT_Long  b )
   {
+#ifdef FT_MULFIX_ASSEMBLER
+
+    return FT_MULFIX_ASSEMBLER( a, b );
+
+#else
+
     FT_Int   s = 1;
     FT_Long  c;
 
 
-    if ( a < 0 ) { a = -a; s = -1; }
-    if ( b < 0 ) { b = -b; s = -s; }
+    if ( a < 0 )
+    {
+      a = -a;
+      s = -1;
+    }
+
+    if ( b < 0 )
+    {
+      b = -b;
+      s = -s;
+    }
 
     c = (FT_Long)( ( (FT_Int64)a * b + 0x8000L ) >> 16 );
-    return ( s > 0 ) ? c : -c ;
+
+    return ( s > 0 ) ? c : -c;
+
+#endif /* FT_MULFIX_ASSEMBLER */
   }
 
@@ -414 +435 @@
              FT_Long  b )
   {
-    /* use inline assembly to speed up things a bit */
-
-#if defined( __GNUC__ ) && defined( i386 )
-
-    FT_Long  result;
-
-
-    __asm__ __volatile__ (
-      "imul  %%edx\n"
-      "movl  %%edx, %%ecx\n"
-      "sarl  $31, %%ecx\n"
-      "addl  $0x8000, %%ecx\n"
-      "addl  %%ecx, %%eax\n"
-      "adcl  $0, %%edx\n"
-      "shrl  $16, %%eax\n"
-      "shll  $16, %%edx\n"
-      "addl  %%edx, %%eax\n"
-      "mov   %%eax, %0\n"
-      : "=a"(result), "+d"(b)
-      : "a"(a)
-      : "%ecx"
-    );
-    return result;
-
-#elif 1
+#ifdef FT_MULFIX_ASSEMBLER
+
+    return FT_MULFIX_ASSEMBLER( a, b );
+
+#elif 0
+
+    /*
+     *  This code is nonportable.  See comment below.
+     *
+     *  However, on a platform where right-shift of a signed quantity fills
+     *  the leftmost bits by copying the sign bit, it might be faster.
+     */
 
     FT_Long   sa, sb;
@@ -447 +455 @@
       return a;
 
+    /*
+     *  This is a clever way of converting a signed number `a' into its
+     *  absolute value (stored back into `a') and its sign.  The sign is
+     *  stored in `sa'; 0 means `a' was positive or zero, and -1 means `a'
+     *  was negative.  (Similarly for `b' and `sb').
+     *
+     *  Unfortunately, it doesn't work (at least not portably).
+     *
+     *  It makes the assumption that right-shift on a negative signed value
+     *  fills the leftmost bits by copying the sign bit.  This is wrong. 
+     *  According to K&R 2nd ed, section `A7.8 Shift Operators' on page 206,
+     *  the result of right-shift of a negative signed value is
+     *  implementation-defined.  At least one implementation fills the
+     *  leftmost bits with 0s (i.e., it is exactly the same as an unsigned
+     *  right shift).  This means that when `a' is negative, `sa' ends up
+     *  with the value 1 rather than -1.  After that, everything else goes
+     *  wrong.
+     */
     sa = ( a >> ( sizeof ( a ) * 8 - 1 ) );
     a  = ( a ^ sa ) - sa;