1 files changed, 46 insertions, 0 deletions
diff --git a/src/libbiguint/bu_div_internal.c b/src/libbiguint/bu_div_internal.c
new file mode 100644
index 0000000..d1be789
--- /dev/null
+++ b/src/libbiguint/bu_div_internal.c
@@ -0,0 +1,46 @@
+/* ISC license. */
+
+#include <errno.h>
+#include <skalibs/uint32.h>
+#include <skalibs/biguint.h>
+
+/*
+   q = a/b, a = a mod b. Assumes b != 0 and qn >= alen - blen + 1.
+*/
+
+void bu_div_internal (uint32 *a, unsigned int an, uint32 const *b, unsigned int bn, uint32 *q, unsigned int qn)
+{
+  unsigned int alen = bu_len(a, an) ;
+  unsigned int blen = bu_len(b, bn) ;
+  bu_zero(q, qn) ;
+  if (alen < blen) return ;
+  {
+    uint32 bb[alen + 1] ;
+    unsigned int i = 1 + ((alen - blen) << 5) ;
+    bu_zero(bb, alen - blen) ;
+    bu_copy_internal(bb + alen - blen, b, blen) ;
+    bb[alen] = 0 ;
+
+    while (bu_cmp(a, alen, bb, alen+1) >= 0)
+    {
+      bu_slb(bb + alen - blen, blen + 1) ;
+      i++ ;
+    }
+    while (i && (bu_cmp(a, alen, bb, alen+1) < 0))
+    {
+      bu_srb(bb, alen + 1) ;
+      i-- ;
+    }
+
+    while (i--)
+    {
+      bu_slb(q, alen - blen + 1) ;
+      if (bu_cmp(a, alen, bb, alen) >= 0)
+      {
+        bu_sub(a, alen, a, alen, bb, alen) ;
+        q[0] |= 1 ;
+      }
+      bu_srb(bb, alen) ;
+    }
+  }
+}