Add generic implementation for muldi3

Since version v2018.08.0 some shared copies of gcc routines got added to
barebox so that archs don't need to have their own copy inside their
lib. The arch I am working on atm also needs support for muldi3 which is
not present as a generic version right now.

This patch adds the generic version from latest linux v4.20 to barebox
and lets the archs select it in their Kconfig so they don't need to
provide it themself.

Signed-off-by: Martin Hofmann <martin.hofmann_at_mni.thm.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

3 files changed, 77 insertions, 0 deletions

diff --git a/lib/Kconfig b/lib/Kconfig
index 67680adbb5..e048aded8b 100644
--- a/lib/Kconfig
+++ b/lib/Kconfig
@@ -145,4 +145,7 @@ config GENERIC_LIB_ASHRDI3
 config GENERIC_LIB_LSHRDI3
 	bool
 
+config GENERIC_LIB_MULDI3
+	bool
+
 endmenu
diff --git a/lib/Makefile b/lib/Makefile
index 8ece2c284f..e72aa6655c 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -72,5 +72,6 @@ obj-$(CONFIG_CRC8)	+= crc8.o
 obj-$(CONFIG_GENERIC_LIB_ASHLDI3) += ashldi3.o
 obj-$(CONFIG_GENERIC_LIB_ASHRDI3) += ashrdi3.o
 obj-$(CONFIG_GENERIC_LIB_LSHRDI3) += lshrdi3.o
+obj-$(CONFIG_GENERIC_LIB_MULDI3)  += muldi3.o
 
 pbl-$(CONFIG_GENERIC_LIB_ASHLDI3) += ashldi3.o
diff --git a/lib/muldi3.c b/lib/muldi3.c
new file mode 100644
index 0000000000..eec810e807
--- /dev/null
+++ b/lib/muldi3.c
@@ -0,0 +1,73 @@
+/*
+ * 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 <module.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);