2fe8fb192f
There is important information about booting non-ack images in docs/UPDATING. ack/aout-format images can't be built any more, and booting clang/ELF-format ones is a little different. Updating to the new boot monitor is recommended. Changes in this commit: . drop boot monitor -> allowing dropping ack support . facility to copy ELF boot files to /boot so that old boot monitor can still boot fairly easily, see UPDATING . no more ack-format libraries -> single-case libraries . some cleanup of OBJECT_FMT, COMPILER_TYPE, etc cases . drop several ack toolchain commands, but not all support commands (e.g. aal is gone but acksize is not yet). . a few libc files moved to netbsd libc dir . new /bin/date as minix date used code in libc/ . test compile fix . harmonize includes . /usr/lib is no longer special: without ack, /usr/lib plays no kind of special bootstrapping role any more and bootstrapping is done exclusively through packages, so releases depend even less on the state of the machine making them now. . rename nbsd_lib* to lib* . reduce mtree
103 lines
3.1 KiB
C
103 lines
3.1 KiB
C
/* $NetBSD: modf_ieee754.c,v 1.3 2010/01/27 14:10:41 drochner Exp $ */
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/*
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* Copyright (c) 1994, 1995 Carnegie-Mellon University.
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* All rights reserved.
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*
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* Author: Chris G. Demetriou
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*
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* Permission to use, copy, modify and distribute this software and
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* its documentation is hereby granted, provided that both the copyright
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* notice and this permission notice appear in all copies of the
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* software, derivative works or modified versions, and any portions
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* thereof, and that both notices appear in supporting documentation.
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*
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* CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
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* CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND
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* FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
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*
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* Carnegie Mellon requests users of this software to return to
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*
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* Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU
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* School of Computer Science
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* Carnegie Mellon University
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* Pittsburgh PA 15213-3890
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*
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* any improvements or extensions that they make and grant Carnegie the
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* rights to redistribute these changes.
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*/
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#include <sys/types.h>
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#include <machine/ieee.h>
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#include <errno.h>
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#include <math.h>
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/*
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* double modf(double val, double *iptr)
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* returns: f and i such that |f| < 1.0, (f + i) = val, and
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* sign(f) == sign(i) == sign(val).
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*
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* Beware signedness when doing subtraction, and also operand size!
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*/
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double
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modf(double val, double *iptr)
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{
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union ieee_double_u u, v;
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u_int64_t frac;
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/*
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* If input is +/-Inf or NaN, return +/-0 or NaN.
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*/
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u.dblu_d = val;
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if (u.dblu_dbl.dbl_exp == DBL_EXP_INFNAN) {
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*iptr = u.dblu_d;
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return (0.0 / u.dblu_d);
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}
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/*
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* If input can't have a fractional part, return
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* (appropriately signed) zero, and make i be the input.
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*/
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if ((int)u.dblu_dbl.dbl_exp - DBL_EXP_BIAS > DBL_FRACBITS - 1) {
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*iptr = u.dblu_d;
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v.dblu_d = 0.0;
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v.dblu_dbl.dbl_sign = u.dblu_dbl.dbl_sign;
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return (v.dblu_d);
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}
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/*
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* If |input| < 1.0, return it, and set i to the appropriately
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* signed zero.
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*/
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if (u.dblu_dbl.dbl_exp < DBL_EXP_BIAS) {
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v.dblu_d = 0.0;
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v.dblu_dbl.dbl_sign = u.dblu_dbl.dbl_sign;
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*iptr = v.dblu_d;
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return (u.dblu_d);
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}
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/*
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* There can be a fractional part of the input.
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* If you look at the math involved for a few seconds, it's
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* plain to see that the integral part is the input, with the
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* low (DBL_FRACBITS - (exponent - DBL_EXP_BIAS)) bits zeroed,
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* the fractional part is the part with the rest of the
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* bits zeroed. Just zeroing the high bits to get the
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* fractional part would yield a fraction in need of
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* normalization. Therefore, we take the easy way out, and
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* just use subtraction to get the fractional part.
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*/
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v.dblu_d = u.dblu_d;
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/* Zero the low bits of the fraction, the sleazy way. */
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frac = ((u_int64_t)v.dblu_dbl.dbl_frach << 32) + v.dblu_dbl.dbl_fracl;
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frac >>= DBL_FRACBITS - (u.dblu_dbl.dbl_exp - DBL_EXP_BIAS);
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frac <<= DBL_FRACBITS - (u.dblu_dbl.dbl_exp - DBL_EXP_BIAS);
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v.dblu_dbl.dbl_fracl = frac & 0xffffffff;
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v.dblu_dbl.dbl_frach = frac >> 32;
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*iptr = v.dblu_d;
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u.dblu_d -= v.dblu_d;
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u.dblu_dbl.dbl_sign = v.dblu_dbl.dbl_sign;
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return (u.dblu_d);
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}
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