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author | Jing Yu <jingyu@google.com> | 2011-12-20 10:27:58 -0800 |
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committer | Jing Yu <jingyu@google.com> | 2011-12-20 10:27:58 -0800 |
commit | cf3cdbf8b3cda61a619299e7966a83df66244036 (patch) | |
tree | 201e2bcfc955f16802d3257112d29736cb3a3ce8 /binutils-2.21/gas/flonum-mult.c | |
parent | e4df3e0a5bb640ccfa2f30ee67fe9b3146b152d6 (diff) | |
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Add binutils-2.21.
Use --enable-gold=default for dual linker support.
Change-Id: Id1a744c7db58a0b5e7a3be174cdfa875f2f86e49
Diffstat (limited to 'binutils-2.21/gas/flonum-mult.c')
-rw-r--r-- | binutils-2.21/gas/flonum-mult.c | 188 |
1 files changed, 188 insertions, 0 deletions
diff --git a/binutils-2.21/gas/flonum-mult.c b/binutils-2.21/gas/flonum-mult.c new file mode 100644 index 0000000..e5f32fc --- /dev/null +++ b/binutils-2.21/gas/flonum-mult.c @@ -0,0 +1,188 @@ +/* flonum_mult.c - multiply two flonums + Copyright 1987, 1990, 1991, 1992, 1995, 2000, 2002, 2003, 2007 + 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 + | + ... | ... a .b + | 1 0 + | + | ... + | + | + | + | ___ + | \ + +----- 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 ...) */ + +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++) + { + 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); +#endif + /* 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); +#endif + } + } + significant |= work; + if (significant || P < 0) + { + if (P >= 0) + { + product->low[P] = work; +#ifdef TRACE + 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. */ +#ifdef TRACE + 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 + P--; + product->leader = product->low + P; + product->exponent = exponent; +} |