| /* mpn_submul_1 -- multiply the S1_SIZE long limb vector pointed to by S1_PTR |

| by S2_LIMB, subtract the S1_SIZE least significant limbs of the product |

| from the limb vector pointed to by RES_PTR. Return the most significant |

| limb of the product, adjusted for carry-out from the subtraction. |

| |

| Copyright (C) 1992, 1993, 1994, 1996, 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 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 <config.h> |

| #include "gmp-impl.h" |

| |

| mp_limb_t |

| mpn_submul_1 (res_ptr, s1_ptr, s1_size, s2_limb) |

| register mp_ptr res_ptr; |

| register mp_srcptr s1_ptr; |

| mp_size_t s1_size; |

| register mp_limb_t s2_limb; |

| { |

| register mp_limb_t cy_limb; |

| register mp_size_t j; |

| register mp_limb_t prod_high, prod_low; |

| register mp_limb_t x; |

| |

| /* The loop counter and index J goes from -SIZE to -1. This way |

| the loop becomes faster. */ |

| j = -s1_size; |

| |

| /* Offset the base pointers to compensate for the negative indices. */ |

| res_ptr -= j; |

| s1_ptr -= j; |

| |

| cy_limb = 0; |

| do |

| { |

| umul_ppmm (prod_high, prod_low, s1_ptr[j], s2_limb); |

| |

| prod_low += cy_limb; |

| cy_limb = (prod_low < cy_limb) + prod_high; |

| |

| x = res_ptr[j]; |

| prod_low = x - prod_low; |

| cy_limb += (prod_low > x); |

| res_ptr[j] = prod_low; |

| } |

| while (++j != 0); |

| |

| return cy_limb; |

| } |