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Diffstat (limited to 'stdlib/mod_1.c')
| -rw-r--r-- | stdlib/mod_1.c | 197 |
1 files changed, 0 insertions, 197 deletions
diff --git a/stdlib/mod_1.c b/stdlib/mod_1.c deleted file mode 100644 index 3273c9222d..0000000000 --- a/stdlib/mod_1.c +++ /dev/null @@ -1,197 +0,0 @@ -/* mpn_mod_1(dividend_ptr, dividend_size, divisor_limb) -- - Divide (DIVIDEND_PTR,,DIVIDEND_SIZE) by DIVISOR_LIMB. - Return the single-limb remainder. - There are no constraints on the value of the divisor. - -Copyright (C) 1991, 1993, 1994, 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 2.1 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; see the file COPYING.LIB. If not, write to -the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, -MA 02111-1307, USA. */ - -#include <gmp.h> -#include "gmp-impl.h" -#include "longlong.h" - -#ifndef UMUL_TIME -#define UMUL_TIME 1 -#endif - -#ifndef UDIV_TIME -#define UDIV_TIME UMUL_TIME -#endif - -/* FIXME: We should be using invert_limb (or invert_normalized_limb) - here (not udiv_qrnnd). */ - -mp_limb_t -#if __STDC__ -mpn_mod_1 (mp_srcptr dividend_ptr, mp_size_t dividend_size, - mp_limb_t divisor_limb) -#else -mpn_mod_1 (dividend_ptr, dividend_size, divisor_limb) - mp_srcptr dividend_ptr; - mp_size_t dividend_size; - mp_limb_t divisor_limb; -#endif -{ - mp_size_t i; - mp_limb_t n1, n0, r; - int dummy; - - /* Botch: Should this be handled at all? Rely on callers? */ - if (dividend_size == 0) - return 0; - - /* If multiplication is much faster than division, and the - dividend is large, pre-invert the divisor, and use - only multiplications in the inner loop. */ - - /* This test should be read: - Does it ever help to use udiv_qrnnd_preinv? - && Does what we save compensate for the inversion overhead? */ - if (UDIV_TIME > (2 * UMUL_TIME + 6) - && (UDIV_TIME - (2 * UMUL_TIME + 6)) * dividend_size > UDIV_TIME) - { - int normalization_steps; - - count_leading_zeros (normalization_steps, divisor_limb); - if (normalization_steps != 0) - { - mp_limb_t divisor_limb_inverted; - - divisor_limb <<= normalization_steps; - - /* Compute (2**2N - 2**N * DIVISOR_LIMB) / DIVISOR_LIMB. The - result is a (N+1)-bit approximation to 1/DIVISOR_LIMB, with the - most significant bit (with weight 2**N) implicit. */ - - /* Special case for DIVISOR_LIMB == 100...000. */ - if (divisor_limb << 1 == 0) - divisor_limb_inverted = ~(mp_limb_t) 0; - else - udiv_qrnnd (divisor_limb_inverted, dummy, - -divisor_limb, 0, divisor_limb); - - n1 = dividend_ptr[dividend_size - 1]; - r = n1 >> (BITS_PER_MP_LIMB - normalization_steps); - - /* Possible optimization: - if (r == 0 - && divisor_limb > ((n1 << normalization_steps) - | (dividend_ptr[dividend_size - 2] >> ...))) - ...one division less... */ - - for (i = dividend_size - 2; i >= 0; i--) - { - n0 = dividend_ptr[i]; - udiv_qrnnd_preinv (dummy, r, r, - ((n1 << normalization_steps) - | (n0 >> (BITS_PER_MP_LIMB - normalization_steps))), - divisor_limb, divisor_limb_inverted); - n1 = n0; - } - udiv_qrnnd_preinv (dummy, r, r, - n1 << normalization_steps, - divisor_limb, divisor_limb_inverted); - return r >> normalization_steps; - } - else - { - mp_limb_t divisor_limb_inverted; - - /* Compute (2**2N - 2**N * DIVISOR_LIMB) / DIVISOR_LIMB. The - result is a (N+1)-bit approximation to 1/DIVISOR_LIMB, with the - most significant bit (with weight 2**N) implicit. */ - - /* Special case for DIVISOR_LIMB == 100...000. */ - if (divisor_limb << 1 == 0) - divisor_limb_inverted = ~(mp_limb_t) 0; - else - udiv_qrnnd (divisor_limb_inverted, dummy, - -divisor_limb, 0, divisor_limb); - - i = dividend_size - 1; - r = dividend_ptr[i]; - - if (r >= divisor_limb) - r = 0; - else - i--; - - for (; i >= 0; i--) - { - n0 = dividend_ptr[i]; - udiv_qrnnd_preinv (dummy, r, r, - n0, divisor_limb, divisor_limb_inverted); - } - return r; - } - } - else - { - if (UDIV_NEEDS_NORMALIZATION) - { - int normalization_steps; - - count_leading_zeros (normalization_steps, divisor_limb); - if (normalization_steps != 0) - { - divisor_limb <<= normalization_steps; - - n1 = dividend_ptr[dividend_size - 1]; - r = n1 >> (BITS_PER_MP_LIMB - normalization_steps); - - /* Possible optimization: - if (r == 0 - && divisor_limb > ((n1 << normalization_steps) - | (dividend_ptr[dividend_size - 2] >> ...))) - ...one division less... */ - - for (i = dividend_size - 2; i >= 0; i--) - { - n0 = dividend_ptr[i]; - udiv_qrnnd (dummy, r, r, - ((n1 << normalization_steps) - | (n0 >> (BITS_PER_MP_LIMB - normalization_steps))), - divisor_limb); - n1 = n0; - } - udiv_qrnnd (dummy, r, r, - n1 << normalization_steps, - divisor_limb); - return r >> normalization_steps; - } - } - /* No normalization needed, either because udiv_qrnnd doesn't require - it, or because DIVISOR_LIMB is already normalized. */ - - i = dividend_size - 1; - r = dividend_ptr[i]; - - if (r >= divisor_limb) - r = 0; - else - i--; - - for (; i >= 0; i--) - { - n0 = dividend_ptr[i]; - udiv_qrnnd (dummy, r, r, n0, divisor_limb); - } - return r; - } -} |