summaryrefslogtreecommitdiff
path: root/lib/muldi3.c
diff options
context:
space:
mode:
Diffstat (limited to 'lib/muldi3.c')
-rw-r--r--lib/muldi3.c72
1 files changed, 72 insertions, 0 deletions
diff --git a/lib/muldi3.c b/lib/muldi3.c
new file mode 100644
index 000000000000..88938543e10a
--- /dev/null
+++ b/lib/muldi3.c
@@ -0,0 +1,72 @@
+/*
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, see the file COPYING, or write
+ * to the Free Software Foundation, Inc.
+ */
+
+#include <linux/export.h>
+#include <lib/libgcc.h>
+
+#define W_TYPE_SIZE 32
+
+#define __ll_B ((unsigned long) 1 << (W_TYPE_SIZE / 2))
+#define __ll_lowpart(t) ((unsigned long) (t) & (__ll_B - 1))
+#define __ll_highpart(t) ((unsigned long) (t) >> (W_TYPE_SIZE / 2))
+
+/* If we still don't have umul_ppmm, define it using plain C. */
+#if !defined(umul_ppmm)
+#define umul_ppmm(w1, w0, u, v) \
+ do { \
+ unsigned long __x0, __x1, __x2, __x3; \
+ unsigned short __ul, __vl, __uh, __vh; \
+ \
+ __ul = __ll_lowpart(u); \
+ __uh = __ll_highpart(u); \
+ __vl = __ll_lowpart(v); \
+ __vh = __ll_highpart(v); \
+ \
+ __x0 = (unsigned long) __ul * __vl; \
+ __x1 = (unsigned long) __ul * __vh; \
+ __x2 = (unsigned long) __uh * __vl; \
+ __x3 = (unsigned long) __uh * __vh; \
+ \
+ __x1 += __ll_highpart(__x0); /* this can't give carry */\
+ __x1 += __x2; /* but this indeed can */ \
+ if (__x1 < __x2) /* did we get it? */ \
+ __x3 += __ll_B; /* yes, add it in the proper pos */ \
+ \
+ (w1) = __x3 + __ll_highpart(__x1); \
+ (w0) = __ll_lowpart(__x1) * __ll_B + __ll_lowpart(__x0);\
+ } while (0)
+#endif
+
+#if !defined(__umulsidi3)
+#define __umulsidi3(u, v) ({ \
+ DWunion __w; \
+ umul_ppmm(__w.s.high, __w.s.low, u, v); \
+ __w.ll; \
+ })
+#endif
+
+long long notrace __muldi3(long long u, long long v)
+{
+ const DWunion uu = {.ll = u};
+ const DWunion vv = {.ll = v};
+ DWunion w = {.ll = __umulsidi3(uu.s.low, vv.s.low)};
+
+ w.s.high += ((unsigned long) uu.s.low * (unsigned long) vv.s.high
+ + (unsigned long) uu.s.high * (unsigned long) vv.s.low);
+
+ return w.ll;
+}
+EXPORT_SYMBOL(__muldi3);