1 files changed, 61 insertions, 0 deletions
diff --git a/lib/udivsi3.c b/lib/udivsi3.c
new file mode 100644
index 000000000..16af22858
--- /dev/null
+++ b/lib/udivsi3.c
@@ -0,0 +1,61 @@
+//===-- udivsi3.c - Implement __udivsi3 -----------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file implements __udivsi3 for the compiler_rt library.
+//
+//===----------------------------------------------------------------------===//
+
+#include "int_lib.h"
+
+// Returns: a / b
+
+// Translated from Figure 3-40 of The PowerPC Compiler Writer's Guide
+
+su_int
+__udivsi3(su_int n, su_int d)
+{
+    const unsigned n_uword_bits = sizeof(su_int) * CHAR_BIT;
+    su_int q;
+    su_int r;
+    unsigned sr;
+    // special cases
+    if (d == 0)
+        return 0; // ?!
+    if (n == 0)
+        return 0;
+    sr = __builtin_clz(d) - __builtin_clz(n);
+    // 0 <= sr <= n_uword_bits - 1 or sr large
+    if (sr > n_uword_bits - 1)  // d > r
+        return 0;
+    if (sr == n_uword_bits - 1)  // d == 1
+        return n;
+    ++sr;
+    // 1 <= sr <= n_uword_bits - 1
+    // Not a special case
+    q = n << (n_uword_bits - sr);
+    r = n >> sr;
+    su_int carry = 0;
+    for (; sr > 0; --sr)
+    {
+        // r:q = ((r:q)  << 1) | carry
+        r = (r << 1) | (q >> (n_uword_bits - 1));
+        q = (q << 1) | carry;
+        // carry = 0;
+        // if (r.all >= d.all)
+        // {
+        //      r.all -= d.all;
+        //      carry = 1;
+        // }
+        const si_int s = (si_int)(d - r - 1) >> (n_uword_bits - 1);
+        carry = s & 1;
+        r -= d & s;
+    }
+    q = (q << 1) | carry;
+    return q;
+}