diff options
author | Linus Torvalds <torvalds@ppc970.osdl.org> | 2005-04-16 15:20:36 -0700 |
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committer | Linus Torvalds <torvalds@ppc970.osdl.org> | 2005-04-16 15:20:36 -0700 |
commit | 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (patch) | |
tree | 0bba044c4ce775e45a88a51686b5d9f90697ea9d /arch/mips/math-emu/sp_sqrt.c |
Linux-2.6.12-rc2v2.6.12-rc2
Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.
Let it rip!
Diffstat (limited to 'arch/mips/math-emu/sp_sqrt.c')
-rw-r--r-- | arch/mips/math-emu/sp_sqrt.c | 117 |
1 files changed, 117 insertions, 0 deletions
diff --git a/arch/mips/math-emu/sp_sqrt.c b/arch/mips/math-emu/sp_sqrt.c new file mode 100644 index 000000000000..8a934b9f7eb8 --- /dev/null +++ b/arch/mips/math-emu/sp_sqrt.c @@ -0,0 +1,117 @@ +/* IEEE754 floating point arithmetic + * single precision square root + */ +/* + * MIPS floating point support + * Copyright (C) 1994-2000 Algorithmics Ltd. + * http://www.algor.co.uk + * + * ######################################################################## + * + * This program is free software; you can distribute it and/or modify it + * under the terms of the GNU General Public License (Version 2) as + * published by the Free Software Foundation. + * + * This program is distributed in the hope 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 this program; if not, write to the Free Software Foundation, Inc., + * 59 Temple Place - Suite 330, Boston MA 02111-1307, USA. + * + * ######################################################################## + */ + + +#include "ieee754sp.h" + +ieee754sp ieee754sp_sqrt(ieee754sp x) +{ + int ix, s, q, m, t, i; + unsigned int r; + COMPXSP; + + /* take care of Inf and NaN */ + + EXPLODEXSP; + CLEARCX; + FLUSHXSP; + + /* x == INF or NAN? */ + switch (xc) { + case IEEE754_CLASS_QNAN: + /* sqrt(Nan) = Nan */ + return ieee754sp_nanxcpt(x, "sqrt"); + case IEEE754_CLASS_SNAN: + SETCX(IEEE754_INVALID_OPERATION); + return ieee754sp_nanxcpt(ieee754sp_indef(), "sqrt"); + case IEEE754_CLASS_ZERO: + /* sqrt(0) = 0 */ + return x; + case IEEE754_CLASS_INF: + if (xs) { + /* sqrt(-Inf) = Nan */ + SETCX(IEEE754_INVALID_OPERATION); + return ieee754sp_nanxcpt(ieee754sp_indef(), "sqrt"); + } + /* sqrt(+Inf) = Inf */ + return x; + case IEEE754_CLASS_DNORM: + case IEEE754_CLASS_NORM: + if (xs) { + /* sqrt(-x) = Nan */ + SETCX(IEEE754_INVALID_OPERATION); + return ieee754sp_nanxcpt(ieee754sp_indef(), "sqrt"); + } + break; + } + + ix = x.bits; + + /* normalize x */ + m = (ix >> 23); + if (m == 0) { /* subnormal x */ + for (i = 0; (ix & 0x00800000) == 0; i++) + ix <<= 1; + m -= i - 1; + } + m -= 127; /* unbias exponent */ + ix = (ix & 0x007fffff) | 0x00800000; + if (m & 1) /* odd m, double x to make it even */ + ix += ix; + m >>= 1; /* m = [m/2] */ + + /* generate sqrt(x) bit by bit */ + ix += ix; + q = s = 0; /* q = sqrt(x) */ + r = 0x01000000; /* r = moving bit from right to left */ + + while (r != 0) { + t = s + r; + if (t <= ix) { + s = t + r; + ix -= t; + q += r; + } + ix += ix; + r >>= 1; + } + + if (ix != 0) { + SETCX(IEEE754_INEXACT); + switch (ieee754_csr.rm) { + case IEEE754_RP: + q += 2; + break; + case IEEE754_RN: + q += (q & 1); + break; + } + } + ix = (q >> 1) + 0x3f000000; + ix += (m << 23); + x.bits = ix; + return x; +} |