mirror of
https://github.com/kanjitalk755/macemu.git
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106 lines
2.9 KiB
C++
106 lines
2.9 KiB
C++
/*
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* fpu/mathlib.cpp - Floating-point math support library
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*
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* Copyright (c) 2001-2004 Milan Jurik of ARAnyM dev team (see AUTHORS)
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*
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* Inspired by Christian Bauer's Basilisk II
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*
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* This file is part of the ARAnyM project which builds a new and powerful
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* TOS/FreeMiNT compatible virtual machine running on almost any hardware.
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*
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* MC68881/68040 fpu emulation
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*
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* Original UAE FPU, copyright 1996 Herman ten Brugge
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* Rewrite for x86, copyright 1999-2001 Lauri Pesonen
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* New framework, copyright 2000-2001 Gwenole Beauchesne
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* Adapted for JIT compilation (c) Bernd Meyer, 2000-2001
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*
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* ARAnyM is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* ARAnyM is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with ARAnyM; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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*/
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/* NOTE: this file shall be included only from fpu/fpu_*.cpp */
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#undef PRIVATE
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#define PRIVATE static
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#undef PUBLIC
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#define PUBLIC /**/
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#undef FFPU
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#define FFPU /**/
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#undef FPU
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#define FPU fpu.
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#if defined(FPU_IEEE) && defined(USE_X87_ASSEMBLY)
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PRIVATE fpu_extended fp_do_pow(fpu_extended x, fpu_extended y)
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{
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fpu_extended value, exponent;
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uae_s64 p = (uae_s64)y;
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if (x == 0.0) {
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if (y > 0.0)
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return (y == (double) p && (p & 1) != 0 ? x : 0.0);
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else if (y < 0.0)
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return (y == (double) p && (-p & 1) != 0 ? 1.0 / x : 1.0 / fp_fabs (x));
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}
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if (y == (double) p) {
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fpu_extended r = 1.0;
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if (p == 0)
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return 1.0;
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if (p < 0) {
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p = -p;
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x = 1.0 / x;
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}
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while (1) {
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if (p & 1)
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r *= x;
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p >>= 1;
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if (p == 0)
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return r;
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x *= x;
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}
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}
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__asm__ __volatile__("fyl2x" : "=t" (value) : "0" (x), "u" (1.0) : "st(1)");
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__asm__ __volatile__("fmul %%st(1) # y * log2(x)\n\t"
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"fst %%st(1)\n\t"
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"frndint # int(y * log2(x))\n\t"
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"fxch\n\t"
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"fsub %%st(1) # fract(y * log2(x))\n\t"
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"f2xm1 # 2^(fract(y * log2(x))) - 1\n\t"
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: "=t" (value), "=u" (exponent) : "0" (y), "1" (value));
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value += 1.0;
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__asm__ __volatile__("fscale" : "=t" (value) : "0" (value), "u" (exponent));
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return value;
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}
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PRIVATE fpu_extended fp_do_log1p(fpu_extended x)
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{
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// TODO: handle NaN and +inf/-inf
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fpu_extended value;
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// The fyl2xp1 can only be used for values in
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// -1 + sqrt(2) / 2 <= x <= 1 - sqrt(2) / 2
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// 0.29 is a safe value.
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if (fp_fabs(x) <= 0.29)
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__asm__ __volatile__("fldln2; fxch; fyl2xp1" : "=t" (value) : "0" (x));
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else
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__asm__ __volatile__("fldln2; fxch; fyl2x" : "=t" (value) : "0" (x + 1.0));
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return value;
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}
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#endif
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