2a51c00a70
so I've changed it to 0x127f. 64 bit precision causes errors in paranoia and our math library, changing to 53 bit precision solves these problems. I've been told that long double support in Gcc 2.5 requires 64 bit mode, so a comprehensive FP strategy (compiler, library, FPU, emulator) will have to be addressed in the future.
138 lines
5.0 KiB
C
138 lines
5.0 KiB
C
/*-
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* Copyright (c) 1990 The Regents of the University of California.
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* All rights reserved.
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*
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* This code is derived from software contributed to Berkeley by
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* William Jolitz.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by the University of
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* California, Berkeley and its contributors.
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* 4. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* from: @(#)npx.h 5.3 (Berkeley) 1/18/91
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* $Id: npx.h,v 1.9 1994/01/25 19:58:30 jtc Exp $
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*/
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/*
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* 287/387 NPX Coprocessor Data Structures and Constants
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* W. Jolitz 1/90
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*/
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#ifndef _I386_NPX_H_
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#define _I386_NPX_H_
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/* Environment information of floating point unit */
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struct env87 {
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long en_cw; /* control word (16bits) */
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long en_sw; /* status word (16bits) */
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long en_tw; /* tag word (16bits) */
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long en_fip; /* floating point instruction pointer */
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u_short en_fcs; /* floating code segment selector */
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u_short en_opcode; /* opcode last executed (11 bits ) */
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long en_foo; /* floating operand offset */
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long en_fos; /* floating operand segment selector */
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};
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/* Contents of each floating point accumulator */
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struct fpacc87 {
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#ifdef dontdef /* too unportable */
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u_long fp_mantlo; /* mantissa low (31:0) */
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u_long fp_manthi; /* mantissa high (63:32) */
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int fp_exp:15; /* exponent */
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int fp_sgn:1; /* mantissa sign */
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#else
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u_char fp_bytes[10];
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#endif
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};
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/* Floating point context */
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struct save87 {
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struct env87 sv_env; /* floating point control/status */
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struct fpacc87 sv_ac[8]; /* accumulator contents, 0-7 */
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#ifndef dontdef
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u_long sv_ex_sw; /* status word for last exception (was pad) */
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u_long sv_ex_tw; /* tag word for last exception (was pad) */
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u_char sv_pad[8 * 2 - 2 * 4]; /* bogus historical padding */
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#endif
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};
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/* Cyrix EMC memory - mapped coprocessor context switch information */
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struct emcsts {
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long em_msw; /* memory mapped status register when swtched */
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long em_tar; /* memory mapped temp A register when swtched */
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long em_dl; /* memory mapped D low register when swtched */
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};
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/* Intel prefers long real (53 bit) precision */
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#define __iBCS_NPXCW__ 0x262
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/* wfj prefers temporary real (64 bit) precision */
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#define __386BSD_NPXCW__ 0x362
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/* */
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#define __NetBSD_NPXCW__ 0x127f
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/*
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* bde prefers 53 bit precision and all exceptions masked.
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*
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* The standard control word from finit is 0x37F, giving:
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*
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* round to nearest
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* 64-bit precision
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* all exceptions masked.
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*
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* Now I want:
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*
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* affine mode for 287's (if they work at all) (1 in bitfield 1<<12)
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* 53-bit precision (2 in bitfield 3<<8)
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* overflow exception unmasked (0 in bitfield 1<<3)
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* zero divide exception unmasked (0 in bitfield 1<<2)
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* invalid-operand exception unmasked (0 in bitfield 1<<0).
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*
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* 64-bit precision often gives bad results with high level languages
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* because it makes the results of calculations depend on whether
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* intermediate values are stored in memory or in FPU registers.
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*
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* The "Intel" and wfj control words have:
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*
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* underflow exception unmasked (0 in bitfield 1<<4)
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*
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* but that causes an unexpected exception in the test program 'paranoia'
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* and makes denormals useless (DBL_MIN / 2 underflows). It doesn't make
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* a lot of sense to trap underflow without trapping denormals.
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*
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* Later I will want the IEEE default of all exceptions masked. See the
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* 0.0 math manpage for why this is better. The 0.1 math manpage is empty.
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*/
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#define __BDE_NPXCW__ 0x1272
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#define __BETTER_BDE_NPXCW__ 0x127f
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#ifdef __NetBSD__
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#define __INITIAL_NPXCW__ __NetBSD_NPXCW__
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#else
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#define __INITIAL_NPXCW__ __iBCS_NPXCW__
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#endif
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#endif /* !_I386_NPX_H_ */
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