--- /dev/null
+/* mpz_addmul_ui, mpz_submul_ui - add or subtract small multiple.
+
+ THE mpz_aorsmul_1 FUNCTION IN THIS FILE IS FOR INTERNAL USE ONLY AND IS
+ ALMOST CERTAIN TO BE SUBJECT TO INCOMPATIBLE CHANGES OR DISAPPEAR
+ COMPLETELY IN FUTURE GNU MP RELEASES.
+
+Copyright 2001, 2002, 2004, 2005 Free Software Foundation, Inc.
+
+This file is part of the GNU MP Library.
+
+The GNU MP Library is free software; you can redistribute it and/or modify
+it under the terms of the GNU Lesser General Public License as published by
+the Free Software Foundation; either version 3 of the License, or (at your
+option) any later version.
+
+The GNU MP Library 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 Lesser General Public
+License for more details.
+
+You should have received a copy of the GNU Lesser General Public License
+along with the GNU MP Library. If not, see http://www.gnu.org/licenses/. */
+
+#include "gmp.h"
+#include "gmp-impl.h"
+
+
+#if HAVE_NATIVE_mpn_mul_1c
+#define MPN_MUL_1C(cout, dst, src, size, n, cin) \
+ do { \
+ (cout) = mpn_mul_1c (dst, src, size, n, cin); \
+ } while (0)
+#else
+#define MPN_MUL_1C(cout, dst, src, size, n, cin) \
+ do { \
+ mp_limb_t __cy; \
+ __cy = mpn_mul_1 (dst, src, size, n); \
+ (cout) = __cy + mpn_add_1 (dst, dst, size, cin); \
+ } while (0)
+#endif
+
+
+/* sub>=0 means an addmul w += x*y, sub<0 means a submul w -= x*y.
+
+ All that's needed to account for negative w or x is to flip "sub".
+
+ The final w will retain its sign, unless an underflow occurs in a submul
+ of absolute values, in which case it's flipped.
+
+ If x has more limbs than w, then mpn_submul_1 followed by mpn_com_n is
+ used. The alternative would be mpn_mul_1 into temporary space followed
+ by mpn_sub_n. Avoiding temporary space seem good, and submul+com stands
+ a chance of being faster since it involves only one set of carry
+ propagations, not two. Note that doing an addmul_1 with a
+ twos-complement negative y doesn't work, because it effectively adds an
+ extra x * 2^BITS_PER_MP_LIMB. */
+
+REGPARM_ATTR(1) void
+mpz_aorsmul_1 (mpz_ptr w, mpz_srcptr x, mp_limb_t y, mp_size_t sub)
+{
+ mp_size_t xsize, wsize, wsize_signed, new_wsize, min_size, dsize;
+ mp_srcptr xp;
+ mp_ptr wp;
+ mp_limb_t cy;
+
+ /* w unaffected if x==0 or y==0 */
+ xsize = SIZ (x);
+ if (xsize == 0 || y == 0)
+ return;
+
+ sub ^= xsize;
+ xsize = ABS (xsize);
+
+ wsize_signed = SIZ (w);
+ if (wsize_signed == 0)
+ {
+ /* nothing to add to, just set x*y, "sub" gives the sign */
+ MPZ_REALLOC (w, xsize+1);
+ wp = PTR (w);
+ cy = mpn_mul_1 (wp, PTR(x), xsize, y);
+ wp[xsize] = cy;
+ xsize += (cy != 0);
+ SIZ (w) = (sub >= 0 ? xsize : -xsize);
+ return;
+ }
+
+ sub ^= wsize_signed;
+ wsize = ABS (wsize_signed);
+
+ new_wsize = MAX (wsize, xsize);
+ MPZ_REALLOC (w, new_wsize+1);
+ wp = PTR (w);
+ xp = PTR (x);
+ min_size = MIN (wsize, xsize);
+
+ if (sub >= 0)
+ {
+ /* addmul of absolute values */
+
+ cy = mpn_addmul_1 (wp, xp, min_size, y);
+ wp += min_size;
+ xp += min_size;
+
+ dsize = xsize - wsize;
+#if HAVE_NATIVE_mpn_mul_1c
+ if (dsize > 0)
+ cy = mpn_mul_1c (wp, xp, dsize, y, cy);
+ else if (dsize < 0)
+ {
+ dsize = -dsize;
+ cy = mpn_add_1 (wp, wp, dsize, cy);
+ }
+#else
+ if (dsize != 0)
+ {
+ mp_limb_t cy2;
+ if (dsize > 0)
+ cy2 = mpn_mul_1 (wp, xp, dsize, y);
+ else
+ {
+ dsize = -dsize;
+ cy2 = 0;
+ }
+ cy = cy2 + mpn_add_1 (wp, wp, dsize, cy);
+ }
+#endif
+
+ wp[dsize] = cy;
+ new_wsize += (cy != 0);
+ }
+ else
+ {
+ /* submul of absolute values */
+
+ cy = mpn_submul_1 (wp, xp, min_size, y);
+ if (wsize >= xsize)
+ {
+ /* if w bigger than x, then propagate borrow through it */
+ if (wsize != xsize)
+ cy = mpn_sub_1 (wp+xsize, wp+xsize, wsize-xsize, cy);
+
+ if (cy != 0)
+ {
+ /* Borrow out of w, take twos complement negative to get
+ absolute value, flip sign of w. */
+ wp[new_wsize] = ~-cy; /* extra limb is 0-cy */
+ mpn_com_n (wp, wp, new_wsize);
+ new_wsize++;
+ MPN_INCR_U (wp, new_wsize, CNST_LIMB(1));
+ wsize_signed = -wsize_signed;
+ }
+ }
+ else /* wsize < xsize */
+ {
+ /* x bigger than w, so want x*y-w. Submul has given w-x*y, so
+ take twos complement and use an mpn_mul_1 for the rest. */
+
+ mp_limb_t cy2;
+
+ /* -(-cy*b^n + w-x*y) = (cy-1)*b^n + ~(w-x*y) + 1 */
+ mpn_com_n (wp, wp, wsize);
+ cy += mpn_add_1 (wp, wp, wsize, CNST_LIMB(1));
+ cy -= 1;
+
+ /* If cy-1 == -1 then hold that -1 for latter. mpn_submul_1 never
+ returns cy==MP_LIMB_T_MAX so that value always indicates a -1. */
+ cy2 = (cy == MP_LIMB_T_MAX);
+ cy += cy2;
+ MPN_MUL_1C (cy, wp+wsize, xp+wsize, xsize-wsize, y, cy);
+ wp[new_wsize] = cy;
+ new_wsize += (cy != 0);
+
+ /* Apply any -1 from above. The value at wp+wsize is non-zero
+ because y!=0 and the high limb of x will be non-zero. */
+ if (cy2)
+ MPN_DECR_U (wp+wsize, new_wsize-wsize, CNST_LIMB(1));
+
+ wsize_signed = -wsize_signed;
+ }
+
+ /* submul can produce high zero limbs due to cancellation, both when w
+ has more limbs or x has more */
+ MPN_NORMALIZE (wp, new_wsize);
+ }
+
+ SIZ (w) = (wsize_signed >= 0 ? new_wsize : -new_wsize);
+
+ ASSERT (new_wsize == 0 || PTR(w)[new_wsize-1] != 0);
+}
+
+
+void
+mpz_addmul_ui (mpz_ptr w, mpz_srcptr x, unsigned long y)
+{
+#if BITS_PER_ULONG > GMP_NUMB_BITS
+ if (UNLIKELY (y > GMP_NUMB_MAX && SIZ(x) != 0))
+ {
+ mpz_t t;
+ mp_ptr tp;
+ mp_size_t xn;
+ TMP_DECL;
+ TMP_MARK;
+ xn = SIZ (x);
+ MPZ_TMP_INIT (t, ABS (xn) + 1);
+ tp = PTR (t);
+ tp[0] = 0;
+ MPN_COPY (tp + 1, PTR(x), ABS (xn));
+ SIZ(t) = xn >= 0 ? xn + 1 : xn - 1;
+ mpz_aorsmul_1 (w, t, (mp_limb_t) y >> GMP_NUMB_BITS, (mp_size_t) 0);
+ PTR(t) = tp + 1;
+ SIZ(t) = xn;
+ mpz_aorsmul_1 (w, t, (mp_limb_t) y & GMP_NUMB_MASK, (mp_size_t) 0);
+ TMP_FREE;
+ return;
+ }
+#endif
+ mpz_aorsmul_1 (w, x, (mp_limb_t) y, (mp_size_t) 0);
+}
+
+void
+mpz_submul_ui (mpz_ptr w, mpz_srcptr x, unsigned long y)
+{
+#if BITS_PER_ULONG > GMP_NUMB_BITS
+ if (y > GMP_NUMB_MAX && SIZ(x) != 0)
+ {
+ mpz_t t;
+ mp_ptr tp;
+ mp_size_t xn;
+ TMP_DECL;
+ TMP_MARK;
+ xn = SIZ (x);
+ MPZ_TMP_INIT (t, ABS (xn) + 1);
+ tp = PTR (t);
+ tp[0] = 0;
+ MPN_COPY (tp + 1, PTR(x), ABS (xn));
+ SIZ(t) = xn >= 0 ? xn + 1 : xn - 1;
+ mpz_aorsmul_1 (w, t, (mp_limb_t) y >> GMP_NUMB_BITS, (mp_size_t) -1);
+ PTR(t) = tp + 1;
+ SIZ(t) = xn;
+ mpz_aorsmul_1 (w, t, (mp_limb_t) y & GMP_NUMB_MASK, (mp_size_t) -1);
+ TMP_FREE;
+ return;
+ }
+#endif
+ mpz_aorsmul_1 (w, x, (mp_limb_t) y & GMP_NUMB_MASK, (mp_size_t) -1);
+}
projects / msp430-gcc.git / blobdiff