diff --git a/gmp-impl.h b/gmp-impl.h
index fad5eac3..63952244 100644
--- a/gmp-impl.h
+++ b/gmp-impl.h
@@ -2745,6 +2745,70 @@ mp_limb_t mpn_invert_limb _PROTO ((mp_limb_t)) ATTRIBUTE_CONST;
     dinv = v;						\
   } while (0)
 
+#define add_sssaaaaaa(sh, sm, sl, ah, am, al, bh, bm, bl)  \
+  __asm__ ("addq %8,%q2\n\tadcq %6,%q1\n\tadcq %4,%q0"     \
+       : "=r" (sh), "=r" (sm), "=&r" (sl)                  \
+       : "0"  ((mp_limb_t)(ah)), "rme" ((mp_limb_t)(bh)),  \
+         "1"  ((mp_limb_t)(am)), "rme" ((mp_limb_t)(bm)),  \
+         "2"  ((mp_limb_t)(al)), "rme" ((mp_limb_t)(bl)))  \
+
+#define sub_dddmmmsss(sh, sm, sl, ah, am, al, bh, bm, bl)  \
+  __asm__ ("subq %8,%q2\n\tsbbq %6,%q1\n\tsbbq %4,%q0"     \
+       : "=r" (sh), "=r" (sm), "=&r" (sl)                  \
+       : "0"  ((mp_limb_t)(ah)), "rme" ((mp_limb_t)(bh)),  \
+         "1"  ((mp_limb_t)(am)), "rme" ((mp_limb_t)(bm)),  \
+         "2"  ((mp_limb_t)(al)), "rme" ((mp_limb_t)(bl)))  \
+
+#define mpir_invert_pi2(dinv, d1, d2)                        \
+do {                                                         \
+   mp_limb_t __q, __r[2], __p[2], __cy;                      \
+                                                             \
+   if ((d2) + 1 == 0 && (d1) + 1 == 0)                       \
+      (dinv) = 0;                                            \
+   else {                                                    \
+      if ((d1) + 1 == 0)                                     \
+         (dinv) = ~(d1), __r[1] = ~(d2);                     \
+      else                                                   \
+         udiv_qrnnd((dinv), __r[1], ~(d1), ~(d2), (d1) + 1); \
+                                                             \
+      if ((d2) + 1 != 0) {                                   \
+         __r[0] = 0;                                         \
+         umul_ppmm(__p[1], __p[0], (dinv), ~(d2));           \
+         __cy = mpn_add_n(__r, __r, __p, 2);                 \
+                                                             \
+         __p[0] = (d2) + 1, __p[1] = (d1) + ((d2) + 1 == 0); \
+         while (__cy || mpn_cmp(__r, __p, 2) >= 0)           \
+         { (dinv)++; __cy -= mpn_sub_n(__r, __r, __p, 2); }  \
+      }                                                      \
+   }                                                         \
+} while (0)
+
+#define mpir_div32_preinv2(q, a1, a2, a3, d1, d2, dinv)          \
+   do {                                                          \
+      mp_limb_t __q2, __q3, __q4, __r2, __r3, __p1, __p2;        \
+      umul_ppmm((q), __q2, (a1), (dinv));                        \
+      add_ssaaaa((q), __q2, (q), __q2, (a1), (a2));              \
+      umul_ppmm(__p1, __p2, (q), (d2));                          \
+      sub_ddmmss(__r2, __r3, (a2) - (q)*(d1), (a3), __p1, __p2); \
+      sub_ddmmss(__r2, __r3, __r2, __r3, (d1), (d2));            \
+      if (__r2 < __q2) (q)++;                                    \
+   } while (0)
+
+#define mpir_divrem32_preinv2(q, r2, r3, a1, a2, a3, d1, d2, dinv)      \
+   do {                                                                 \
+      mp_limb_t __q2, __q3, __q4, __p1, __p2, __cy;                     \
+      umul_ppmm((q), __q2, (a1), (dinv));                               \
+      add_ssaaaa((q), __q2, (q), __q2, (a1), (a2));                     \
+      umul_ppmm(__p1, __p2, (q), (d2));                                 \
+      (r3) = (a3);                                                      \
+      (r2) = (a2) - (q)*(d1);                                           \
+      sub_ddmmss((r2), (r3), (r2), (r3), __p1, __p2);                   \
+      sub_ddmmss((r2), (r3), (r2), (r3), (d1), (d2));                   \
+      (q)++;                                                            \
+      if ((r2) >= __q2)                                                 \
+      { (q)--; add_ssaaaa((r2), (r3), (r2), (r3), (d1), (d2)); }        \
+   } while (0)
+
 /* Compute quotient the quotient and remainder for n / d. Requires d
    >= B^2 / 2 and n < d B. di is the inverse
 
diff --git a/mpn/generic/sb_div_qr.c b/mpn/generic/sb_div_qr.c
index 7495eb21..ef9f2624 100644
--- a/mpn/generic/sb_div_qr.c
+++ b/mpn/generic/sb_div_qr.c
@@ -40,8 +40,8 @@ mpn_sb_div_qr (mp_ptr qp,
   mp_limb_t qh;
   mp_size_t i;
   mp_limb_t n1, n0;
-  mp_limb_t d1, d0;
-  mp_limb_t cy, cy1;
+  mp_limb_t d1, d0, d01, d11;
+  mp_limb_t cy, cy1, cy2;
   mp_limb_t q;
 
   ASSERT (dn > 2);
@@ -61,6 +61,9 @@ mpn_sb_div_qr (mp_ptr qp,
   d1 = dp[dn + 1];
   d0 = dp[dn + 0];
 
+  d01 = d0 + 1;
+  d11 = d1 + (d01 == 0);
+
   np -= 2;
 
   n1 = np[1];
@@ -76,20 +79,36 @@ mpn_sb_div_qr (mp_ptr qp,
 	}
       else
 	{
-	  tdiv_qr_3by2 (q, n1, n0, n1, np[1], np[0], d1, d0, dinv);
+	  mpir_divrem32_preinv2(q, n1, n0, n1, np[1], np[0], d11, d01, dinv);
 
-	  cy = mpn_submul_1 (np - dn, dp, dn, q);
+     add_sssaaaaaa(cy, n1, n0, 0, n1, n0, 0, 0, q);        
+     while (UNLIKELY(cy != 0 || n1 >= d1))                            
+     { 
+        if (n1 == d1 && n0 < d0 && cy == 0) break;            
+        sub_dddmmmsss(cy, n1, n0, cy, n1, n0, 0, d1, d0); 
+        (q)++; 
+     }                                                          
+
+     cy2 = mpn_submul_1 (np - dn, dp, dn, q);
+
+	  sub_dddmmmsss(cy, n1, n0, 0, n1, n0, 0, 0, cy2);
+     /*cy1 = n0 < cy2;
+	  n0 = (n0 - cy2);
+	  cy = -(n1 < cy1);
+	  n1 = (n1 - cy1);*/
+
+     /*add_sssaaaaaa(cy, n1, n0, cy, n1, n0, 0, 0, q);*/
+     /*cy1 = (n0 + q < n0);
+     n0 = (n0 + q);
+     cy += (n1 + cy1 < n1);
+     n1 = (n1 + cy1);*/
 
-	  cy1 = n0 < cy;
-	  n0 = (n0 - cy) & GMP_NUMB_MASK;
-	  cy = n1 < cy1;
-	  n1 = (n1 - cy1) & GMP_NUMB_MASK;
 	  np[0] = n0;
 
 	  if (UNLIKELY (cy != 0))
 	    {
 	      n1 += d1 + mpn_add_n (np - dn, np - dn, dp, dn + 1);
-	      q--;
+         q--;
 	    }
 	}
 
diff --git a/tests/mpn/t-sb_div_qr.c b/tests/mpn/t-sb_div_qr.c
index 600bd4ed..09d61c0f 100644
--- a/tests/mpn/t-sb_div_qr.c
+++ b/tests/mpn/t-sb_div_qr.c
@@ -64,7 +64,7 @@ check_sb_div_qr (void)
 
       MPN_COPY(np2, np, nn);
       
-      invert_1(dip, dp[dn - 1], dp[dn - 2]);
+      mpir_invert_pi2(dip, dp[dn - 1], dp[dn - 2]);
       
       qn = nn - dn + 1;
          
@@ -82,12 +82,14 @@ check_sb_div_qr (void)
          
          if (rn > nn)
          {
+            printf("iteration = %ld\n", i);
             printf("failed: q*d has too many limbs\n");
             abort();
          }
          
          if (mpn_cmp(rp, np2, nn) > 0)
          {
+            printf("iteration = %ld\n", i);
             printf("failed: remainder negative\n");
             abort();
          }
@@ -104,6 +106,7 @@ check_sb_div_qr (void)
       s = (rn < dn) ? -1 : (rn > dn) ? 1 : mpn_cmp(rp, dp, dn);
       if (s >= 0)
       {
+         printf("iteration = %ld\n", i);
          printf ("failed:\n");
          printf ("nn = %lu, dn = %lu, qn = %lu, rn = %lu\n\n", nn, dn, qn, rn);
          gmp_printf (" np: %Nx\n\n", np2, nn);
@@ -115,6 +118,7 @@ check_sb_div_qr (void)
 
       if (mpn_cmp(rp, np, rn) != 0)
       {
+         printf("iteration = %ld\n", i);
          printf("failed: remainder does not match\n");
          gmp_printf (" np: %Nx\n\n", np2, nn);
          gmp_printf (" dp: %Nx\n\n", dp, dn);