Changeset 52443 in vbox for trunk/include/iprt

Timestamp:

Aug 21, 2014 4:16:19 PM (11 years ago)

Author:

vboxsync

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

95651

Message:

Runtime: added ASMMultU32ByU32DivByU32() and fixed early clobber operands in ASMMultU64ByU32DivByU32

File:

• trunk/include/iprt/asm-math.h (modified) (2 diffs)

trunk/include/iprt/asm-math.h

@@ -322 +322 @@
 
 /**
+ * Multiple a 32-bit by a 32-bit integer and divide the result by a 32-bit integer
+ * using a 64 bit intermediate result.
+ * @note    Don't use 64-bit C arithmetic here since some gcc compilers generate references to
+ *          __udivdi3 and __umoddi3 even if this inline function is not used.
+ *
+ * @returns (u32A * u32B) / u32C.
+ * @param   u32A    The 32-bit value (A).
+ * @param   u32B    The 32-bit value to multiple by A.
+ * @param   u32C    The 32-bit value to divide A*B by.
+ *
+ * @remarks Architecture specific.
+ */
+#if RT_INLINE_ASM_EXTERNAL || !defined(__GNUC__) || (!defined(RT_ARCH_AMD64) && !defined(RT_ARCH_X86))
+DECLASM(uint32_t) ASMMultU32ByU32DivByU32(uint32_t u32A, uint32_t u32B, uint32_t u32C);
+#else
+DECLINLINE(uint32_t) ASMMultU32ByU32DivByU32(uint32_t u32A, uint32_t u32B, uint32_t u32C)
+{
+# if RT_INLINE_ASM_GNU_STYLE
+    uint32_t u32Result, u32Spill;
+    __asm__ __volatile__("mul %2\n\t"
+                         "div %3\n\t"
+                         : "=&a" (u32Result),
+                           "=&d" (u32Spill)
+                         : "r" (u32B),
+                           "r" (u32C),
+                           "0" (u32A),
+                           "1" (0));
+    return u32Result;
+# else
+    return (uint32_t)(((uint64_t)u32A * u32B) / u32C);
+# endif
+}
+#endif
+
+
+/**
  * Multiple a 64-bit by a 32-bit integer and divide the result by a 32-bit integer
  * using a 96 bit intermediate result.
@@ -344 +380 @@
     __asm__ __volatile__("mulq %2\n\t"
                          "divq %3\n\t"
-                         : "=a" (u64Result),
-                           "=d" (u64Spill)
+                         : "=&a" (u64Result),
+                           "=&d" (u64Spill)
                          : "r" ((uint64_t)u32B),
                            "r" ((uint64_t)u32C),