diff options
Diffstat (limited to 'gnu/lib/libgmp/mpz_dmincl.c')
| -rw-r--r-- | gnu/lib/libgmp/mpz_dmincl.c | 172 |
1 files changed, 172 insertions, 0 deletions
diff --git a/gnu/lib/libgmp/mpz_dmincl.c b/gnu/lib/libgmp/mpz_dmincl.c new file mode 100644 index 0000000..dde7981 --- /dev/null +++ b/gnu/lib/libgmp/mpz_dmincl.c @@ -0,0 +1,172 @@ +/* mpz_dmincl.c -- include file for mpz_dm.c, mpz_mod.c, mdiv.c. + +Copyright (C) 1991 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 General Public License as published by +the Free Software Foundation; either version 2, 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 General Public License for more details. + +You should have received a copy of the GNU General Public License +along with the GNU MP Library; see the file COPYING. If not, write to +the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA. */ + +/* THIS CODE IS OBSOLETE. IT WILL SOON BE REPLACED BY CLEANER CODE WITH + LESS MEMORY ALLOCATION OVERHEAD. */ + +/* If den == quot, den needs temporary storage. + If den == rem, den needs temporary storage. + If num == quot, num needs temporary storage. + If den has temporary storage, it can be normalized while being copied, + i.e no extra storage should be allocated. */ + +/* This is the function body of mdiv, mpz_divmod, and mpz_mod. + + If COMPUTE_QUOTIENT is defined, the quotient is put in the MP_INT + object quot, otherwise that variable is not referenced at all. + + The remainder is always computed, and the result is put in the MP_INT + object rem. */ + +{ + mp_ptr np, dp; + mp_ptr qp, rp; + mp_size nsize = num->size; + mp_size dsize = den->size; + mp_size qsize, rsize; + mp_size sign_remainder = nsize; +#ifdef COMPUTE_QUOTIENT + mp_size sign_quotient = nsize ^ dsize; +#endif + unsigned normalization_steps; + + nsize = ABS (nsize); + dsize = ABS (dsize); + + /* Ensure space is enough for quotient and remainder. */ + + /* We need space for an extra limb in the remainder, because it's + up-shifted (normalized) below. */ + rsize = nsize + 1; + if (rem->alloc < rsize) + _mpz_realloc (rem, rsize); + + qsize = nsize - dsize + 1; /* qsize cannot be bigger than this. */ + if (qsize <= 0) + { +#ifdef COMPUTE_QUOTIENT + quot->size = 0; +#endif + if (num != rem) + { + rem->size = num->size; + MPN_COPY (rem->d, num->d, nsize); + } + return; + } + +#ifdef COMPUTE_QUOTIENT + if (quot->alloc < qsize) + _mpz_realloc (quot, qsize); + qp = quot->d; +#else + qp = (mp_ptr) alloca (qsize * BYTES_PER_MP_LIMB); +#endif + np = num->d; + dp = den->d; + rp = rem->d; + + /* Make sure quot and num are different. Otherwise the numerator + would be successively overwritten by the quotient digits. */ + if (qp == np) + { + np = (mp_ptr) alloca (nsize * BYTES_PER_MP_LIMB); + MPN_COPY (np, qp, nsize); + } + + count_leading_zeros (normalization_steps, dp[dsize - 1]); + + /* Normalize the denominator, i.e. make its most significant bit set by + shifting it NORMALIZATION_STEPS bits to the left. Also shift the + numerator the same number of steps (to keep the quotient the same!). */ + if (normalization_steps != 0) + { + mp_ptr tp; + mp_limb ndigit; + + /* Shift up the denominator setting the most significant bit of + the most significant word. Use temporary storage not to clobber + the original contents of the denominator. */ + tp = (mp_ptr) alloca (dsize * BYTES_PER_MP_LIMB); + (void) mpn_lshift (tp, dp, dsize, normalization_steps); + dp = tp; + + /* Shift up the numerator, possibly introducing a new most + significant word. Move the shifted numerator in the remainder + meanwhile. */ + ndigit = mpn_lshift (rp, np, nsize, normalization_steps); + if (ndigit != 0) + { + rp[nsize] = ndigit; + rsize = nsize + 1; + } + else + rsize = nsize; + } + else + { +#ifdef COMPUTE_QUOTIENT + if (rem == den || quot == den) +#else + if (rem == den) +#endif + { + mp_ptr tp; + + tp = (mp_ptr) alloca (dsize * BYTES_PER_MP_LIMB); + MPN_COPY (tp, dp, dsize); + dp = tp; + } + + /* Move the numerator to the remainder. */ + if (rp != np) + MPN_COPY (rp, np, nsize); + + rsize = nsize; + } + + qsize = rsize - dsize + mpn_div (qp, rp, rsize, dp, dsize); + + rsize = dsize; + + /* Normalize the remainder. */ + while (rsize > 0) + { + if (rp[rsize - 1] != 0) + break; + rsize--; + } + + if (normalization_steps != 0) + rsize = mpn_rshift (rp, rp, rsize, normalization_steps); + + rem->size = (sign_remainder >= 0) ? rsize : -rsize; + +#ifdef COMPUTE_QUOTIENT + /* Normalize the quotient. We may have at most one leading + zero-word, so no loop is needed. */ + if (qsize > 0) + qsize -= (qp[qsize - 1] == 0); + + quot->size = (sign_quotient >= 0) ? qsize : -qsize; +#endif + + alloca (0); +} |
