386BSD 0.1 development

Work on file usr/src/usr.bin/gcc/gnulib/longlong/muldi3.c

Co-Authored-By: Lynne Greer Jolitz <ljolitz@cardio.ucsf.edu>
Synthesized-from: 386BSD-0.1

diff --git a/usr/src/usr.bin/gcc/gnulib/longlong/muldi3.c b/usr/src/usr.bin/gcc/gnulib/longlong/muldi3.c
new file mode 100644 (file)
index 0000000..0c7dea8
--- /dev/null
+++ b/usr/src/usr.bin/gcc/gnulib/longlong/muldi3.c
@@ -0,0 +1,54 @@
+#include "longlong.h"
+
+static void bmul ();
+
+long long 
+__muldi3 (u, v)
+     long long u, v;
+{
+  long a[2], b[2], c[2][2];
+  long_long w;
+  long_long uu, vv;
+
+  uu.ll = u;
+  vv.ll = v;
+
+  a[HIGH] = uu.s.high;
+  a[LOW] = uu.s.low;
+  b[HIGH] = vv.s.high;
+  b[LOW] = vv.s.low;
+
+  bmul (a, b, c, sizeof a, sizeof b);
+
+  w.s.high = c[LOW][HIGH];
+  w.s.low = c[LOW][LOW];
+  return w.ll;
+}
+
+static void 
+bmul (a, b, c, m, n)
+    unsigned short *a, *b, *c;
+    size_t m, n;
+{
+  int i, j;
+  unsigned long acc;
+
+  bzero (c, m + n);
+
+  m /= sizeof *a;
+  n /= sizeof *b;
+
+  for (j = little_end (n); is_not_msd (j, n); j = next_msd (j))
+    {
+      unsigned short *c1 = c + j + little_end (2);
+      acc = 0;
+      for (i = little_end (m); is_not_msd (i, m); i = next_msd (i))
+       {
+         /* Widen before arithmetic to avoid loss of high bits.  */
+         acc += (unsigned long) a[i] * b[j] + c1[i];
+         c1[i] = acc & low16;
+         acc = acc >> 16;
+       }
+      c1[i] = acc;
+    }
+}