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Diffstat (limited to 'sys/powerpc/fpu/fpu_subr.c')
| -rw-r--r-- | sys/powerpc/fpu/fpu_subr.c | 216 |
1 files changed, 216 insertions, 0 deletions
diff --git a/sys/powerpc/fpu/fpu_subr.c b/sys/powerpc/fpu/fpu_subr.c new file mode 100644 index 000000000000..1da4f6e6c03a --- /dev/null +++ b/sys/powerpc/fpu/fpu_subr.c @@ -0,0 +1,216 @@ +/* $NetBSD: fpu_subr.c,v 1.4 2005/12/11 12:18:42 christos Exp $ */ + +/* + * SPDX-License-Identifier: BSD-3-Clause + * + * Copyright (c) 1992, 1993 + * The Regents of the University of California. All rights reserved. + * + * This software was developed by the Computer Systems Engineering group + * at Lawrence Berkeley Laboratory under DARPA contract BG 91-66 and + * contributed to Berkeley. + * + * All advertising materials mentioning features or use of this software + * must display the following acknowledgement: + * This product includes software developed by the University of + * California, Lawrence Berkeley Laboratory. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * 3. Neither the name of the University nor the names of its contributors + * may be used to endorse or promote products derived from this software + * without specific prior written permission. + * + * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND + * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE + * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE + * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE + * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL + * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS + * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) + * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT + * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY + * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF + * SUCH DAMAGE. + */ + +/* + * FPU subroutines. + */ + +#include <sys/types.h> +#include <sys/systm.h> + +#include <machine/fpu.h> + +#include <powerpc/fpu/fpu_arith.h> +#include <powerpc/fpu/fpu_emu.h> + +/* + * Shift the given number right rsh bits. Any bits that `fall off' will get + * shoved into the sticky field; we return the resulting sticky. Note that + * shifting NaNs is legal (this will never shift all bits out); a NaN's + * sticky field is ignored anyway. + */ +int +fpu_shr(struct fpn *fp, int rsh) +{ + u_int m0, m1, m2, m3, s; + int lsh; + +#ifdef DIAGNOSTIC + if (rsh <= 0 || (fp->fp_class != FPC_NUM && !ISNAN(fp))) + panic("fpu_rightshift 1"); +#endif + + m0 = fp->fp_mant[0]; + m1 = fp->fp_mant[1]; + m2 = fp->fp_mant[2]; + m3 = fp->fp_mant[3]; + + /* If shifting all the bits out, take a shortcut. */ + if (rsh >= FP_NMANT) { +#ifdef DIAGNOSTIC + if ((m0 | m1 | m2 | m3) == 0) + panic("fpu_rightshift 2"); +#endif + fp->fp_mant[0] = 0; + fp->fp_mant[1] = 0; + fp->fp_mant[2] = 0; + fp->fp_mant[3] = 0; +#ifdef notdef + if ((m0 | m1 | m2 | m3) == 0) + fp->fp_class = FPC_ZERO; + else +#endif + fp->fp_sticky = 1; + return (1); + } + + /* Squish out full words. */ + s = fp->fp_sticky; + if (rsh >= 32 * 3) { + s |= m3 | m2 | m1; + m3 = m0, m2 = 0, m1 = 0, m0 = 0; + } else if (rsh >= 32 * 2) { + s |= m3 | m2; + m3 = m1, m2 = m0, m1 = 0, m0 = 0; + } else if (rsh >= 32) { + s |= m3; + m3 = m2, m2 = m1, m1 = m0, m0 = 0; + } + + /* Handle any remaining partial word. */ + if ((rsh &= 31) != 0) { + lsh = 32 - rsh; + s |= m3 << lsh; + m3 = (m3 >> rsh) | (m2 << lsh); + m2 = (m2 >> rsh) | (m1 << lsh); + m1 = (m1 >> rsh) | (m0 << lsh); + m0 >>= rsh; + } + fp->fp_mant[0] = m0; + fp->fp_mant[1] = m1; + fp->fp_mant[2] = m2; + fp->fp_mant[3] = m3; + fp->fp_sticky = s; + return (s); +} + +/* + * Force a number to be normal, i.e., make its fraction have all zero + * bits before FP_1, then FP_1, then all 1 bits. This is used for denorms + * and (sometimes) for intermediate results. + * + * Internally, this may use a `supernormal' -- a number whose fp_mant + * is greater than or equal to 2.0 -- so as a side effect you can hand it + * a supernormal and it will fix it (provided fp->fp_mant[3] == 0). + */ +void +fpu_norm(struct fpn *fp) +{ + u_int m0, m1, m2, m3, top, sup, nrm; + int lsh, rsh, exp; + + exp = fp->fp_exp; + m0 = fp->fp_mant[0]; + m1 = fp->fp_mant[1]; + m2 = fp->fp_mant[2]; + m3 = fp->fp_mant[3]; + + /* Handle severe subnormals with 32-bit moves. */ + if (m0 == 0) { + if (m1) + m0 = m1, m1 = m2, m2 = m3, m3 = 0, exp -= 32; + else if (m2) + m0 = m2, m1 = m3, m2 = 0, m3 = 0, exp -= 2 * 32; + else if (m3) + m0 = m3, m1 = 0, m2 = 0, m3 = 0, exp -= 3 * 32; + else { + fp->fp_class = FPC_ZERO; + return; + } + } + + /* Now fix any supernormal or remaining subnormal. */ + nrm = FP_1; + sup = nrm << 1; + if (m0 >= sup) { + /* + * We have a supernormal number. We need to shift it right. + * We may assume m3==0. + */ + for (rsh = 1, top = m0 >> 1; top >= sup; rsh++) /* XXX slow */ + top >>= 1; + exp += rsh; + lsh = 32 - rsh; + m3 = m2 << lsh; + m2 = (m2 >> rsh) | (m1 << lsh); + m1 = (m1 >> rsh) | (m0 << lsh); + m0 = top; + } else if (m0 < nrm) { + /* + * We have a regular denorm (a subnormal number), and need + * to shift it left. + */ + for (lsh = 1, top = m0 << 1; top < nrm; lsh++) /* XXX slow */ + top <<= 1; + exp -= lsh; + rsh = 32 - lsh; + m0 = top | (m1 >> rsh); + m1 = (m1 << lsh) | (m2 >> rsh); + m2 = (m2 << lsh) | (m3 >> rsh); + m3 <<= lsh; + } + + fp->fp_exp = exp; + fp->fp_mant[0] = m0; + fp->fp_mant[1] = m1; + fp->fp_mant[2] = m2; + fp->fp_mant[3] = m3; +} + +/* + * Concoct a `fresh' Quiet NaN per Appendix N. + * As a side effect, we set NV (invalid) for the current exceptions. + */ +struct fpn * +fpu_newnan(struct fpemu *fe) +{ + struct fpn *fp; + + fe->fe_cx |= FPSCR_VXSNAN; + fp = &fe->fe_f3; + fp->fp_class = FPC_QNAN; + fp->fp_sign = 0; + fp->fp_mant[0] = FP_1 - 1; + fp->fp_mant[1] = fp->fp_mant[2] = fp->fp_mant[3] = ~0; + DUMPFPN(FPE_REG, fp); + return (fp); +} |