refactor into more fmpr helper functions

fmpr.h

@@ -562,6 +562,10 @@ void fmpr_set_fmpz_2exp(fmpr_t x, const fmpz_t man, const fmpz_t exp);
 
 void fmpr_get_fmpz_2exp(fmpz_t man, fmpz_t exp, const fmpr_t x);
 
+int fmpr_get_fmpz_fixed_fmpz(fmpz_t y, const fmpr_t x, const fmpz_t e);
+
+int fmpr_get_fmpz_fixed_si(fmpz_t y, const fmpr_t x, long e);
+
 static __inline__ void
 fmpr_set_si_2exp_si(fmpr_t x, long man, long exp)
 {

fmpr/get_fmpz_fixed.c

@@ -0,0 +1,63 @@
+/*=============================================================================
+
+    This file is part of ARB.
+
+    ARB 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.
+
+    ARB 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 ARB; if not, write to the Free Software
+    Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
+
+=============================================================================*/
+/******************************************************************************
+
+    Copyright (C) 2012 Fredrik Johansson
+
+******************************************************************************/
+
+#include "fmpr.h"
+
+int
+fmpr_get_fmpz_fixed_fmpz(fmpz_t y, const fmpr_t x, const fmpz_t exp)
+{
+    long shift;
+
+    if (fmpr_is_zero(x))
+    {
+        fmpz_zero(y);
+        return 0;
+    }
+
+    shift = _fmpz_sub_small(fmpr_expref(x), exp);
+
+    if (shift >= 0)
+    {
+        fmpz_mul_2exp(y, fmpr_manref(x), shift);
+        return 0;
+    }
+    else
+    {
+        fmpz_tdiv_q_2exp(y, fmpr_manref(x), -shift);
+        return 1;
+    }
+}
+
+int
+fmpr_get_fmpz_fixed_si(fmpz_t y, const fmpr_t x, long exp)
+{
+    int result;
+    fmpz_t t;
+    fmpz_init(t);
+    fmpz_set_si(t, exp);
+    result = fmpr_get_fmpz_fixed_fmpz(y, x, t);
+    fmpz_clear(t);
+    return result;
+}

fmprb_poly/mullow_ztrunc.c

@@ -136,28 +136,8 @@ void _fmprb_poly_get_fmpz_poly_2exp(fmpr_t error, fmpz_t exp, fmpz  * coeffs,
     /* extract integer polynomial */
     rounding = 0;
     for (i = 0; i < lenA; i++)
-    {
+        rounding |= fmpr_get_fmpz_fixed_fmpz(coeffs + i,
-        if (fmpr_is_zero(fmprb_midref(A + i)))
+                        fmprb_midref(A + i), exp);
-        {
-            fmpz_zero(coeffs + i);
-        }
-        else
-        {
-            shift = _fmpz_sub_small(fmpr_expref(fmprb_midref(A + i)), exp);
-
-            if (shift >= 0)
-            {
-                fmpz_mul_2exp(coeffs + i,
-                    fmpr_manref(fmprb_midref(A + i)), shift);
-            }
-            else
-            {
-                fmpz_tdiv_q_2exp(coeffs + i,
-                    fmpr_manref(fmprb_midref(A + i)), -shift);
-                rounding = 1;
-            }
-        }
-    }
 
     fmpr_zero(error);
 
@@ -185,6 +165,8 @@ void _fmprb_poly_get_fmpz_poly_2exp(fmpr_t error, fmpz_t exp, fmpz  * coeffs,
     fmpz_clear(top_exp);
 }
 
+
+
 void _fmprb_poly_mullow_ztrunc(fmprb_struct * C,
     const fmprb_struct * A, long lenA,
     const fmprb_struct * B, long lenB, long n, long prec)