X-Git-Url: http://git.efficios.com/?a=blobdiff_plain;f=gas%2Fflonum-mult.c;h=ff3c790bd51d45c853028a7164766c74641ff7d3;hb=b4e87f2c1eee99dee805e3828514f8afa162f9ba;hp=c5888c23a32c0719c3374ad7f7bf52973d86897f;hpb=8b228fe958bcac8cf510ce2ed3d9ae24a717334e;p=deliverable%2Fbinutils-gdb.git diff --git a/gas/flonum-mult.c b/gas/flonum-mult.c index c5888c23a3..ff3c790bd5 100644 --- a/gas/flonum-mult.c +++ b/gas/flonum-mult.c @@ -1,45 +1,43 @@ -/* flonum_multip.c - multiply two flonums - Copyright (C) 1987, 1990, 1991 Free Software Foundation, Inc. - - 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. - - 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. */ +/* flonum_mult.c - multiply two flonums + Copyright (C) 1987-2019 Free Software Foundation, Inc. + This file is part of GAS, the GNU Assembler. + + 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. + + 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 @@ -55,145 +53,135 @@ | \ +----- 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 */ - 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. */ - int N; /* As in sum above. */ - int A; /* Which [] of a? */ - int B; /* Which [] of b? */ - - if((a->sign!='-' && a->sign!='+') || (b->sign!='-' && b->sign!='+')) { - /* ... - Got to fail somehow. Any suggestions? */ - product->sign=0; - return; - } - product -> sign = (a->sign == b->sign) ? '+' : '-'; - size_of_a = a -> leader - a -> low; - size_of_b = b -> leader - b -> low; - exponent = a -> exponent + b -> exponent; - size_of_product = product -> high - product -> low; - size_of_sum = size_of_a + size_of_b; - 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. */ - } - else - { - P = 0; - } - carry = 0; - significant = 0; - for (N = 0; - N <= size_of_sum; - N++) + 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. */ + int N; /* As in sum above. */ + int A; /* Which [] of a? */ + int B; /* Which [] of b? */ + + if ((a->sign != '-' && a->sign != '+') + || (b->sign != '-' && b->sign != '+')) + { + /* Got to fail somehow. Any suggestions? */ + product->sign = 0; + return; + } + product->sign = (a->sign == b->sign) ? '+' : '-'; + size_of_a = a->leader - a->low; + size_of_b = b->leader - b->low; + exponent = a->exponent + b->exponent; + size_of_product = product->high - product->low; + size_of_sum = size_of_a + size_of_b; + 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. */ + } + else + { + P = 0; + } + carry = 0; + significant = 0; + for (N = 0; N <= size_of_sum; N++) + { + work = carry; + carry = 0; + for (A = 0; A <= N; A++) + { + B = N - A; + if (A <= size_of_a && B <= size_of_b && B >= 0) { - work = carry; - carry = 0; - 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]; - carry += work >> LITTLENUM_NUMBER_OF_BITS; - work &= LITTLENUM_MASK; + /* 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 - printf("work=%08x carry=%04x\n", work, carry); + printf ("work=%08x carry=%04x\n", work, carry); #endif - } - } - significant |= work; - if (significant || P<0) - { - if (P >= 0) - { - product -> low [P] = work; + } + } + significant |= work; + if (significant || P < 0) + { + if (P >= 0) + { + product->low[P] = work; #ifdef TRACE - printf("P=%d. work[p]:=%04x\n", P, work); + printf ("P=%d. work[p]:=%04x\n", P, work); #endif - } - P ++; - } - else - { - extra_product_positions ++; - exponent ++; - } } - /* - * [P]-> position # size_of_sum + 1. - * This is where 'carry' should go. - */ + P++; + } + else + { + extra_product_positions++; + exponent++; + } + } + /* [P]-> position # size_of_sum + 1. + This is where 'carry' should go. */ #ifdef TRACE - printf("final carry =%04x\n", carry); + printf ("final carry =%04x\n", carry); #endif - if (carry) - { - if (extra_product_positions > 0) - { - product -> low [P] = carry; - } - else - { - /* 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 --) - { - work = * q; - * q = carry; - carry = work; - } - } - } - else + if (carry) + { + if (extra_product_positions > 0) + product->low[P] = carry; + else + { + /* 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--) { - P --; + work = *q; + *q = carry; + carry = work; } - product -> leader = product -> low + P; - product -> exponent = exponent; + } + } + else + P--; + product->leader = product->low + P; + product->exponent = exponent; } - -/* end of flonum_mult.c */