1 files changed, 48 insertions, 0 deletions
diff --git a/src/arch/i386/include/div64.h b/src/arch/i386/include/div64.h
new file mode 100644
index 0000000000..28ed8b296a
--- /dev/null
+++ b/src/arch/i386/include/div64.h
@@ -0,0 +1,48 @@
+#ifndef __I386_DIV64
+#define __I386_DIV64
+
+/*
+ * do_div() is NOT a C function. It wants to return
+ * two values (the quotient and the remainder), but
+ * since that doesn't work very well in C, what it
+ * does is:
+ *
+ * - modifies the 64-bit dividend _in_place_
+ * - returns the 32-bit remainder
+ *
+ * This ends up being the most efficient "calling
+ * convention" on x86.
+ */
+#define do_div(n,base) ({ \
+	unsigned long __upper, __low, __high, __mod, __base; \
+	__base = (base); \
+	asm("":"=a" (__low), "=d" (__high):"A" (n)); \
+	__upper = __high; \
+	if (__high) { \
+		__upper = __high % (__base); \
+		__high = __high / (__base); \
+	} \
+	asm("divl %2":"=a" (__low), "=d" (__mod):"rm" (__base), "0" (__low), "1" (__upper)); \
+	asm("":"=A" (n):"a" (__low),"d" (__high)); \
+	__mod; \
+})
+
+/*
+ * (long)X = ((long long)divs) / (long)div
+ * (long)rem = ((long long)divs) % (long)div
+ *
+ * Warning, this will do an exception if X overflows.
+ */
+#define div_long_long_rem(a,b,c) div_ll_X_l_rem(a,b,c)
+
+extern inline long
+div_ll_X_l_rem(long long divs, long div, long *rem)
+{
+	long dum2;
+      __asm__("divl %2":"=a"(dum2), "=d"(*rem)
+      :	"rm"(div), "A"(divs));
+
+	return dum2;
+
+}
+#endif