Re: rpcrt4: Introduce a new function, safe_multiply, which will raise an exception if a multiply overflows a 4-byte integer.

[Robert Shearman]

Alexandre Julliard wrote:

Robert Shearman <[EMAIL PROTECTED]> writes:

+    unsigned char overflow;
+#if defined(__i386__) && defined (__GNUC__)
+    __asm__(
+            "mull %3\n\t"
+            "seto %%cl"
+            : "=a" (ret), "=c" (overflow) /* outputs: eax, cl */
+            : "%a" (a), "rm" (b) /* inputs: eax, any register or memory
+                                  * address (params are interchangable) */
+            : "edx" /* edx clobbered */);
+#else
+    ret = a * b;
+    overflow = (b && (ret / b != a));
+#endif

That asm seems really overkill. Something like:

 ULONGLONG ret = (ULONGLONG)a * b;
 if (ret > 0xffffffff)

will generate pretty much the same code with a recent gcc, and it's a
lot more readable.

Indeed it does. I'll resubmit the patch set with this change.

--
Rob Shearman