xdr_float.c revision 2
ab25eeb551a4be927a4b6ae2cf8aff7ed17decb4yz * CDDL HEADER START
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ab25eeb551a4be927a4b6ae2cf8aff7ed17decb4yz * Common Development and Distribution License (the "License").
7ddc9b1afd18f260b9fb78ec7732facd91769131Darren Reed * You may not use this file except in compliance with the License.
ab25eeb551a4be927a4b6ae2cf8aff7ed17decb4yz * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
ab25eeb551a4be927a4b6ae2cf8aff7ed17decb4yz * See the License for the specific language governing permissions
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ab25eeb551a4be927a4b6ae2cf8aff7ed17decb4yz * Copyright (c) 1989, 2011, Oracle and/or its affiliates. All rights reserved.
ab25eeb551a4be927a4b6ae2cf8aff7ed17decb4yz/* Copyright (c) 1983, 1984, 1985, 1986, 1987, 1988, 1989 AT&T */
ab25eeb551a4be927a4b6ae2cf8aff7ed17decb4yz/* All Rights Reserved */
ab25eeb551a4be927a4b6ae2cf8aff7ed17decb4yz * Portions of this source code were derived from Berkeley
ab25eeb551a4be927a4b6ae2cf8aff7ed17decb4yz * 4.3 BSD under license from the Regents of the University of
ab25eeb551a4be927a4b6ae2cf8aff7ed17decb4yz * California.
ab25eeb551a4be927a4b6ae2cf8aff7ed17decb4yz * Generic XDR routines impelmentation.
ab25eeb551a4be927a4b6ae2cf8aff7ed17decb4yz * These are the "floating point" xdr routines used to (de)serialize
ab25eeb551a4be927a4b6ae2cf8aff7ed17decb4yz * most common data items. See xdr.h for more info on the interface to
ab25eeb551a4be927a4b6ae2cf8aff7ed17decb4yz * This routine works on Suns, 3b2, 68000s, 386 and Vaxen in a manner
ab25eeb551a4be927a4b6ae2cf8aff7ed17decb4yz * which is very efficient as bit twiddling is all that is needed. All
ab25eeb551a4be927a4b6ae2cf8aff7ed17decb4yz * other machines can use this code but the code is inefficient as
ab25eeb551a4be927a4b6ae2cf8aff7ed17decb4yz * various mathematical operations are used to generate the ieee format.
ab25eeb551a4be927a4b6ae2cf8aff7ed17decb4yz * In addition rounding errors may occur due to the calculations involved.
ab25eeb551a4be927a4b6ae2cf8aff7ed17decb4yz * To be most efficient, new machines should have their own ifdefs.
ab25eeb551a4be927a4b6ae2cf8aff7ed17decb4yz * The encoding routines will fail if the machines try to encode a
ab25eeb551a4be927a4b6ae2cf8aff7ed17decb4yz * float/double whose value can not be represented by the ieee format,
ab25eeb551a4be927a4b6ae2cf8aff7ed17decb4yz * e.g. the exponent is too big/small.
f4b3ec61df05330d25f55a36b975b4d7519fdeb1dh * ieee largest float = (2 ^ 128) * 0x1.fffff
ab25eeb551a4be927a4b6ae2cf8aff7ed17decb4yz * ieee smallest float = (2 ^ -127) * 0x1.00000
ab25eeb551a4be927a4b6ae2cf8aff7ed17decb4yz * ieee largest double = (2 ^ 1024) * 0x1.fffff
ab25eeb551a4be927a4b6ae2cf8aff7ed17decb4yz * ieee smallest double = (2 ^ -1023) * 0x1.00000
ab25eeb551a4be927a4b6ae2cf8aff7ed17decb4yz * The decoding routines assumes that the receiving machine can handle
193974072f41a843678abf5f61979c748687e66bSherry Moore * floats/doubles as large/small as the values stated above. If you
ab25eeb551a4be927a4b6ae2cf8aff7ed17decb4yz * use a machine which can not represent these values, you will need
ab25eeb551a4be927a4b6ae2cf8aff7ed17decb4yz * to put ifdefs in the decode sections to identify areas of failure.
ab25eeb551a4be927a4b6ae2cf8aff7ed17decb4yz#if defined(vax)
f4b3ec61df05330d25f55a36b975b4d7519fdeb1dh * What IEEE single precision floating point looks like this on a
ab25eeb551a4be927a4b6ae2cf8aff7ed17decb4yz/* Vax single precision floating point */
ab25eeb551a4be927a4b6ae2cf8aff7ed17decb4yzstatic struct sgl_limits {
ab25eeb551a4be927a4b6ae2cf8aff7ed17decb4yz#endif /* vax */
ab25eeb551a4be927a4b6ae2cf8aff7ed17decb4yz#if defined(vax)
7ddc9b1afd18f260b9fb78ec7732facd91769131Darren Reed#if defined(mc68000) || defined(sparc) || defined(u3b2) || \
7ddc9b1afd18f260b9fb78ec7732facd91769131Darren Reed defined(u3b15) || defined(i386) || defined(__amd64)
ab25eeb551a4be927a4b6ae2cf8aff7ed17decb4yz#if defined(vax)
ab25eeb551a4be927a4b6ae2cf8aff7ed17decb4yz /* map these to subnormals */
ab25eeb551a4be927a4b6ae2cf8aff7ed17decb4yz /* lose some precision */
ab25eeb551a4be927a4b6ae2cf8aff7ed17decb4yz i < (int)(sizeof (sgl_limits) /
ab25eeb551a4be927a4b6ae2cf8aff7ed17decb4yz sizeof (struct sgl_limits));
ab25eeb551a4be927a4b6ae2cf8aff7ed17decb4yz * Every machine can do this, its just not very efficient.
ab25eeb551a4be927a4b6ae2cf8aff7ed17decb4yz * In addtion, some rounding errors may occur do to the
ab25eeb551a4be927a4b6ae2cf8aff7ed17decb4yz * calculations involved.
ab25eeb551a4be927a4b6ae2cf8aff7ed17decb4yz if (f == 0) {
ab25eeb551a4be927a4b6ae2cf8aff7ed17decb4yz if (f < 0) {
ab25eeb551a4be927a4b6ae2cf8aff7ed17decb4yz f = 0 - f;
ab25eeb551a4be927a4b6ae2cf8aff7ed17decb4yz while (f < 1) {
ab25eeb551a4be927a4b6ae2cf8aff7ed17decb4yz f = f * 2;
ab25eeb551a4be927a4b6ae2cf8aff7ed17decb4yz while (f >= 2) {
ab25eeb551a4be927a4b6ae2cf8aff7ed17decb4yz /* over or under flowing ieee exponent */
ab25eeb551a4be927a4b6ae2cf8aff7ed17decb4yz#if defined(mc68000) || defined(sparc) || defined(u3b2) || \
ab25eeb551a4be927a4b6ae2cf8aff7ed17decb4yz#if defined(vax)
ab25eeb551a4be927a4b6ae2cf8aff7ed17decb4yz i < (int)(sizeof (sgl_limits) /
ab25eeb551a4be927a4b6ae2cf8aff7ed17decb4yz sizeof (struct sgl_limits));
ab25eeb551a4be927a4b6ae2cf8aff7ed17decb4yz /* Special Case */
ab25eeb551a4be927a4b6ae2cf8aff7ed17decb4yz } /* else */
7ddc9b1afd18f260b9fb78ec7732facd91769131Darren Reed vsp->exp = is.exp - IEEE_SNG_BIAS + VAX_SNG_BIAS;
7ddc9b1afd18f260b9fb78ec7732facd91769131Darren Reed * Every machine can do this, its just not very
7ddc9b1afd18f260b9fb78ec7732facd91769131Darren Reed * efficient. It assumes that the decoding machine's
7ddc9b1afd18f260b9fb78ec7732facd91769131Darren Reed * float can represent any value in the range of
7ddc9b1afd18f260b9fb78ec7732facd91769131Darren Reed * ieee largest float = (2 ^ 128) * 0x1.fffff
7ddc9b1afd18f260b9fb78ec7732facd91769131Darren Reed * ieee smallest float = (2 ^ -127) * 0x1.00000
7ddc9b1afd18f260b9fb78ec7732facd91769131Darren Reed * In addtion, some rounding errors may occur do to the
7ddc9b1afd18f260b9fb78ec7732facd91769131Darren Reed * calculations involved.
ab25eeb551a4be927a4b6ae2cf8aff7ed17decb4yz /* 2 ^ -23 */
ab25eeb551a4be927a4b6ae2cf8aff7ed17decb4yz while (exp != 0) {
f4b3ec61df05330d25f55a36b975b4d7519fdeb1dh if (exp < 0) {
ab25eeb551a4be927a4b6ae2cf8aff7ed17decb4yz f = f * 2.0;
ab25eeb551a4be927a4b6ae2cf8aff7ed17decb4yz f = 0 - f;
ab25eeb551a4be927a4b6ae2cf8aff7ed17decb4yz * This routine works on Suns (Sky / 68000's) and Vaxen.
ab25eeb551a4be927a4b6ae2cf8aff7ed17decb4yz#if defined(vax)
ab25eeb551a4be927a4b6ae2cf8aff7ed17decb4yz/* What IEEE double precision floating point looks like on a Vax */
ab25eeb551a4be927a4b6ae2cf8aff7ed17decb4yz/* Vax double precision floating point */
ab25eeb551a4be927a4b6ae2cf8aff7ed17decb4yzstatic struct dbl_limits {
193974072f41a843678abf5f61979c748687e66bSherry Moore {{ 0x7f, 0xff, 0x0, 0xffff, 0xffff, 0xffff }, /* Max Vax */
ab25eeb551a4be927a4b6ae2cf8aff7ed17decb4yz#endif /* vax */
ab25eeb551a4be927a4b6ae2cf8aff7ed17decb4yz#if defined(vax)
193974072f41a843678abf5f61979c748687e66bSherry Moore#if defined(mc68000) || defined(u3b2) || defined(u3b15) || \
ab25eeb551a4be927a4b6ae2cf8aff7ed17decb4yz return (XDR_PUTINT32(xdrs, lp++) && XDR_PUTINT32(xdrs, lp));
ab25eeb551a4be927a4b6ae2cf8aff7ed17decb4yz return (XDR_PUTINT32(xdrs, lp--) && XDR_PUTINT32(xdrs, lp));
ab25eeb551a4be927a4b6ae2cf8aff7ed17decb4yz#if defined(vax)
ab25eeb551a4be927a4b6ae2cf8aff7ed17decb4yz i < (int)(sizeof (dbl_limits) /
193974072f41a843678abf5f61979c748687e66bSherry Moore sizeof (struct dbl_limits));
ab25eeb551a4be927a4b6ae2cf8aff7ed17decb4yz id.mantissa1 = (vd.mantissa1 << 13) | (vd.mantissa2 >> 3);
f4b3ec61df05330d25f55a36b975b4d7519fdeb1dh * Every machine can do this, its just not very efficient.
f4b3ec61df05330d25f55a36b975b4d7519fdeb1dh * In addtion, some rounding errors may occur do to the
f4b3ec61df05330d25f55a36b975b4d7519fdeb1dh * calculations involved.
f4b3ec61df05330d25f55a36b975b4d7519fdeb1dh if (d == 0) {
f4b3ec61df05330d25f55a36b975b4d7519fdeb1dh if (d < 0) {
f4b3ec61df05330d25f55a36b975b4d7519fdeb1dh d = 0 - d;
f4b3ec61df05330d25f55a36b975b4d7519fdeb1dh while (d < 1) {
f4b3ec61df05330d25f55a36b975b4d7519fdeb1dh d = d * 2;
f4b3ec61df05330d25f55a36b975b4d7519fdeb1dh while (d >= 2) {
7ddc9b1afd18f260b9fb78ec7732facd91769131Darren Reed /* over or under flowing ieee exponent */
f4b3ec61df05330d25f55a36b975b4d7519fdeb1dh * 4294967296);
f4b3ec61df05330d25f55a36b975b4d7519fdeb1dh /* 2 ^ 32 */
23f4867fdff96a11dd674de6259a5a0d0a13251cnordmark return (XDR_PUTINT32(xdrs, lp++) && XDR_PUTINT32(xdrs, lp));
7ddc9b1afd18f260b9fb78ec7732facd91769131Darren Reed#if defined(mc68000) || defined(u3b2) || defined(u3b15) || \
7ddc9b1afd18f260b9fb78ec7732facd91769131Darren Reed return (XDR_GETINT32(xdrs, lp++) && XDR_GETINT32(xdrs, lp));
7ddc9b1afd18f260b9fb78ec7732facd91769131Darren Reed return (XDR_GETINT32(xdrs, lp--) && XDR_GETINT32(xdrs, lp));
7ddc9b1afd18f260b9fb78ec7732facd91769131Darren Reed if (!XDR_GETINT32(xdrs, lp++) || !XDR_GETINT32(xdrs, lp))
7ddc9b1afd18f260b9fb78ec7732facd91769131Darren Reed i < sizeof (dbl_limits) /
7ddc9b1afd18f260b9fb78ec7732facd91769131Darren Reed sizeof (struct dbl_limits);
7ddc9b1afd18f260b9fb78ec7732facd91769131Darren Reed vd.mantissa2 = ((id.mantissa1 & MASK(13)) << 3) |
f4b3ec61df05330d25f55a36b975b4d7519fdeb1dh * Every machine can do this, its just not very
f4b3ec61df05330d25f55a36b975b4d7519fdeb1dh * efficient. It assumes that the decoding machine's
f4b3ec61df05330d25f55a36b975b4d7519fdeb1dh * double can represent any value in the range of
f4b3ec61df05330d25f55a36b975b4d7519fdeb1dh * ieee largest double = (2 ^ 1024) * 0x1.fffffffffffff
f4b3ec61df05330d25f55a36b975b4d7519fdeb1dh * ieee smallest double = (2 ^ -1023) * 0x1.0000000000000
193974072f41a843678abf5f61979c748687e66bSherry Moore * In addtion, some rounding errors may occur do to the
f4b3ec61df05330d25f55a36b975b4d7519fdeb1dh * calculations involved.
f4b3ec61df05330d25f55a36b975b4d7519fdeb1dh if (!XDR_GETINT32(xdrs, lp++) || !XDR_GETINT32(xdrs, lp))
f4b3ec61df05330d25f55a36b975b4d7519fdeb1dh /* 2 ^ -20 */
7ddc9b1afd18f260b9fb78ec7732facd91769131Darren Reed /* 2 ^ -52 */
f4b3ec61df05330d25f55a36b975b4d7519fdeb1dh while (exp != 0) {
7ddc9b1afd18f260b9fb78ec7732facd91769131Darren Reed d = d * 2.0;
f4b3ec61df05330d25f55a36b975b4d7519fdeb1dh d = 0 - d;
7ddc9b1afd18f260b9fb78ec7732facd91769131Darren Reed/* ARGSUSED */
f4b3ec61df05330d25f55a36b975b4d7519fdeb1dh * The Sparc uses IEEE FP encoding, so just do a byte copy
f4b3ec61df05330d25f55a36b975b4d7519fdeb1dh#if !defined(sparc)
7ddc9b1afd18f260b9fb78ec7732facd91769131Darren Reed return (XDR_PUTBYTES(xdrs, (char *)fp, sizeof (long double)));
f4b3ec61df05330d25f55a36b975b4d7519fdeb1dh return (XDR_GETBYTES(xdrs, (char *)fp, sizeof (long double)));