X-Git-Url: http://git.efficios.com/?a=blobdiff_plain;f=gas%2Fflonum-mult.c;h=fe7ecc1f31a566eaa77915473c3b84f780e3b31f;hb=74375d182e992778ef8701278c02a742db6be77e;hp=14fbd7d25f475435db4fa7893777b88b081d474f;hpb=e98fe4f7b54cbdf29aef9287bbb1bea8801dd05a;p=deliverable%2Fbinutils-gdb.git diff --git a/gas/flonum-mult.c b/gas/flonum-mult.c index 14fbd7d25f..fe7ecc1f31 100644 --- a/gas/flonum-mult.c +++ b/gas/flonum-mult.c @@ -1,45 +1,43 @@ /* flonum_mult.c - multiply two flonums - Copyright (C) 1987, 1990, 1991, 1992 Free Software Foundation, Inc. + Copyright (C) 1987-2020 Free Software Foundation, Inc. - This file is part of Gas, the GNU Assembler. + This file is part of GAS, the GNU Assembler. - The GNU assembler is distributed in the hope that it will be - useful, but WITHOUT ANY WARRANTY. No author or distributor - accepts responsibility to anyone for the consequences of using it - or for whether it serves any particular purpose or works at all, - unless he says so in writing. Refer to the GNU Assembler General - Public License for full details. + GAS 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 3, or (at your option) + any later version. - Everyone is granted permission to copy, modify and redistribute - the GNU Assembler, but only under the conditions described in the - GNU Assembler General Public License. A copy of this license is - supposed to have been given to you along with the GNU Assembler - so you can know your rights and responsibilities. It should be - in a file named COPYING. Among other things, the copyright - notice and this notice must be preserved on all copies. */ + GAS 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 GAS; see the file COPYING. If not, write to the Free + Software Foundation, 51 Franklin Street - Fifth Floor, Boston, MA + 02110-1301, USA. */ + +#include "ansidecl.h" #include "flonum.h" /* plan for a . b => p(roduct) - - + +-------+-------+-/ /-+-------+-------+ | a | a | ... | a | a | | A | A-1 | | 1 | 0 | +-------+-------+-/ /-+-------+-------+ - - + +-------+-------+-/ /-+-------+-------+ | b | b | ... | b | b | | B | B-1 | | 1 | 0 | +-------+-------+-/ /-+-------+-------+ - - + +-------+-------+-/ /-+-------+-/ /-+-------+-------+ | p | p | ... | p | ... | p | p | | A+B+1| A+B | | N | | 1 | 0 | +-------+-------+-/ /-+-------+-/ /-+-------+-------+ - + /^\ (carry) a .b ... | ... a .b a .b A B | 0 1 0 0 @@ -55,49 +53,46 @@ | \ +----- P = > a .b N /__ i j - + N = 0 ... A+B - + for all i,j where i+j=N [i,j integers > 0] - + a[], b[], p[] may not intersect. Zero length factors signify 0 significant bits: treat as 0.0. 0.0 factors do the right thing. Zero length product OK. - + I chose the ForTran accent "foo[bar]" instead of the C accent "*garply" because I felt the ForTran way was more intuitive. The C way would probably yield better code on most C compilers. Dean Elsner. - (C style also gives deeper insight [to me] ... oh well ...) - */ + (C style also gives deeper insight [to me] ... oh well ...) */ -void -flonum_multip (a, b, product) - const FLONUM_TYPE *a; - const FLONUM_TYPE *b; - FLONUM_TYPE *product; +void +flonum_multip (const FLONUM_TYPE *a, const FLONUM_TYPE *b, + FLONUM_TYPE *product) { - int size_of_a; /* 0 origin */ - int size_of_b; /* 0 origin */ - int size_of_product; /* 0 origin */ - int size_of_sum; /* 0 origin */ - int extra_product_positions; /* 1 origin */ + int size_of_a; /* 0 origin */ + int size_of_b; /* 0 origin */ + int size_of_product; /* 0 origin */ + int size_of_sum; /* 0 origin */ + int extra_product_positions; /* 1 origin */ unsigned long work; unsigned long carry; long exponent; LITTLENUM_TYPE *q; long significant; /* TRUE when we emit a non-0 littlenum */ - /* ForTran accent follows. */ - int P; /* Scan product low-order -> high. */ + /* ForTran accent follows. */ + int P; /* Scan product low-order -> high. */ int N; /* As in sum above. */ - int A; /* Which [] of a? */ - int B; /* Which [] of b? */ + int A; /* Which [] of a? */ + int B; /* Which [] of b? */ - if ((a->sign != '-' && a->sign != '+') || (b->sign != '-' && b->sign != '+')) + if ((a->sign != '-' && a->sign != '+') + || (b->sign != '-' && b->sign != '+')) { - /* ... - Got to fail somehow. Any suggestions? */ + /* Got to fail somehow. Any suggestions? */ product->sign = 0; return; } @@ -110,8 +105,8 @@ flonum_multip (a, b, product) extra_product_positions = size_of_product - size_of_sum; if (extra_product_positions < 0) { - P = extra_product_positions; /* P < 0 */ - exponent -= extra_product_positions; /* Increases exponent. */ + P = extra_product_positions; /* P < 0 */ + exponent -= extra_product_positions; /* Increases exponent. */ } else { @@ -119,23 +114,24 @@ flonum_multip (a, b, product) } carry = 0; significant = 0; - for (N = 0; - N <= size_of_sum; - N++) + for (N = 0; N <= size_of_sum; N++) { work = carry; carry = 0; - for (A = 0; - A <= N; - A++) + for (A = 0; A <= N; A++) { B = N - A; if (A <= size_of_a && B <= size_of_b && B >= 0) { #ifdef TRACE - printf ("a:low[%d.]=%04x b:low[%d.]=%04x work_before=%08x\n", A, a->low[A], B, b->low[B], work); + printf ("a:low[%d.]=%04x b:low[%d.]=%04x work_before=%08x\n", + A, a->low[A], B, b->low[B], work); #endif - work += a->low[A] * b->low[B]; + /* Watch out for sign extension! Without the casts, on + the DEC Alpha, the multiplication result is *signed* + int, which gets sign-extended to convert to the + unsigned long! */ + work += (unsigned long) a->low[A] * (unsigned long) b->low[B]; carry += work >> LITTLENUM_NUMBER_OF_BITS; work &= LITTLENUM_MASK; #ifdef TRACE @@ -161,28 +157,22 @@ flonum_multip (a, b, product) exponent++; } } - /* - * [P]-> position # size_of_sum + 1. - * This is where 'carry' should go. - */ + /* [P]-> position # size_of_sum + 1. + This is where 'carry' should go. */ #ifdef TRACE printf ("final carry =%04x\n", carry); #endif if (carry) { if (extra_product_positions > 0) - { - product->low[P] = carry; - } + product->low[P] = carry; else { - /* No room at high order for carry littlenum. */ - /* Shift right 1 to make room for most significant littlenum. */ + /* No room at high order for carry littlenum. */ + /* Shift right 1 to make room for most significant littlenum. */ exponent++; P--; - for (q = product->low + P; - q >= product->low; - q--) + for (q = product->low + P; q >= product->low; q--) { work = *q; *q = carry; @@ -191,11 +181,7 @@ flonum_multip (a, b, product) } } else - { - P--; - } + P--; product->leader = product->low + P; product->exponent = exponent; } - -/* end of flonum_mult.c */