/* $OpenBSD: fpu_explode.c,v 1.12 2024/03/29 21:02:11 miod Exp $ */ /* * 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. 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, Berkeley and its contributors. * 4. 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_explode.c 8.1 (Berkeley) 6/11/93 * $NetBSD: fpu_explode.c,v 1.5 2000/08/03 18:32:08 eeh Exp $ */ /* * FPU subroutines: `explode' the machine's `packed binary' format numbers * into our internal format. */ #include <sys/types.h> #include <machine/fsr.h> #include <machine/ieee.h> #include <machine/instr.h> #include "fpu_arith.h" #include "fpu_emu.h" #include "fpu_extern.h" #include "fpu_reg.h" /* * N.B.: in all of the following, we assume the FP format is * * --------------------------- * | s | exponent | fraction | * --------------------------- * * (which represents -1**s * 1.fraction * 2**exponent), so that the * sign bit is way at the top (bit 31), the exponent is next, and * then the remaining bits mark the fraction. A zero exponent means * zero or denormalized (0.fraction rather than 1.fraction), and the * maximum possible exponent, 2bias+1, signals inf (fraction==0) or NaN. * * Since the sign bit is always the topmost bit---this holds even for * integers---we set that outside all the *tof functions. Each function * returns the class code for the new number (but note that we use * FPC_QNAN for all NaNs; fpu_explode will fix this if appropriate). */ /* * int -> fpn. */ int __fpu_itof(fp, i) struct fpn *fp; u_int i; { if (i == 0) return (FPC_ZERO); /* * The value FP_1 represents 2^FP_LG, so set the exponent * there and let normalization fix it up. Convert negative * numbers to sign-and-magnitude. Note that this relies on * fpu_norm()'s handling of `supernormals'; see fpu_subr.c. */ fp->fp_exp = FP_LG; fp->fp_mant[0] = (fp->fp_sign && (int)i < 0) ? -i : i; fp->fp_mant[1] = 0; fp->fp_mant[2] = 0; fp->fp_mant[3] = 0; __fpu_norm(fp); return (FPC_NUM); } /* * uint -> fpn. */ int __fpu_uitof(fp, i) struct fpn *fp; u_int i; { if (i == 0) return (FPC_ZERO); /* * The value FP_1 represents 2^FP_LG, so set the exponent * there and let normalization fix it up. * Note that this relies on fpu_norm()'s handling of * `supernormals'; see fpu_subr.c. */ fp->fp_exp = FP_LG; fp->fp_mant[0] = i; fp->fp_mant[1] = 0; fp->fp_mant[2] = 0; fp->fp_mant[3] = 0; __fpu_norm(fp); return (FPC_NUM); } /* * 64-bit int -> fpn. */ int __fpu_xtof(fp, i) struct fpn *fp; u_int64_t i; { if (i == 0) return (FPC_ZERO); /* * The value FP_1 represents 2^FP_LG, so set the exponent * there and let normalization fix it up. Convert negative * numbers to sign-and-magnitude. Note that this relies on * fpu_norm()'s handling of `supernormals'; see fpu_subr.c. */ fp->fp_exp = FP_LG2; i = (fp->fp_sign && (int64_t)i < 0) ? -i : i; fp->fp_mant[0] = (i >> 32) & 0xffffffff; fp->fp_mant[1] = (i >> 0) & 0xffffffff; fp->fp_mant[2] = 0; fp->fp_mant[3] = 0; __fpu_norm(fp); return (FPC_NUM); } /* * 64-bit uint -> fpn. */ int __fpu_uxtof(fp, i) struct fpn *fp; u_int64_t i; { if (i == 0) return (FPC_ZERO); /* * The value FP_1 represents 2^FP_LG, so set the exponent * there and let normalization fix it up. * Note that this relies on fpu_norm()'s handling of * `supernormals'; see fpu_subr.c. */ fp->fp_exp = FP_LG2; fp->fp_mant[0] = (i >> 32) & 0xffffffff; fp->fp_mant[1] = (i >> 0) & 0xffffffff; fp->fp_mant[2] = 0; fp->fp_mant[3] = 0; __fpu_norm(fp); return (FPC_NUM); } #define mask(nbits) ((1L << (nbits)) - 1) /* * All external floating formats convert to internal in the same manner, * as defined here. Note that only normals get an implied 1.0 inserted. */ #define FP_TOF(exp, expbias, allfrac, f0, f1, f2, f3) \ if (exp == 0) { \ if (allfrac == 0) \ return (FPC_ZERO); \ fp->fp_exp = 1 - expbias; \ fp->fp_mant[0] = f0; \ fp->fp_mant[1] = f1; \ fp->fp_mant[2] = f2; \ fp->fp_mant[3] = f3; \ __fpu_norm(fp); \ return (FPC_NUM); \ } \ if (exp == (2 * expbias + 1)) { \ if (allfrac == 0) \ return (FPC_INF); \ fp->fp_mant[0] = f0; \ fp->fp_mant[1] = f1; \ fp->fp_mant[2] = f2; \ fp->fp_mant[3] = f3; \ return (FPC_QNAN); \ } \ fp->fp_exp = exp - expbias; \ fp->fp_mant[0] = FP_1 | f0; \ fp->fp_mant[1] = f1; \ fp->fp_mant[2] = f2; \ fp->fp_mant[3] = f3; \ return (FPC_NUM) /* * 32-bit single precision -> fpn. * We assume a single occupies at most (64-FP_LG) bits in the internal * format: i.e., needs at most fp_mant[0] and fp_mant[1]. */ int __fpu_stof(fp, i) struct fpn *fp; u_int i; { int exp; u_int frac, f0, f1; #define SNG_SHIFT (SNG_FRACBITS - FP_LG) exp = (i >> (32 - 1 - SNG_EXPBITS)) & mask(SNG_EXPBITS); frac = i & mask(SNG_FRACBITS); f0 = frac >> SNG_SHIFT; f1 = frac << (32 - SNG_SHIFT); FP_TOF(exp, SNG_EXP_BIAS, frac, f0, f1, 0, 0); } /* * 64-bit double -> fpn. * We assume this uses at most (96-FP_LG) bits. */ int __fpu_dtof(fp, i, j) struct fpn *fp; u_int i, j; { int exp; u_int frac, f0, f1, f2; #define DBL_SHIFT (DBL_FRACBITS - 32 - FP_LG) exp = (i >> (32 - 1 - DBL_EXPBITS)) & mask(DBL_EXPBITS); frac = i & mask(DBL_FRACBITS - 32); f0 = frac >> DBL_SHIFT; f1 = (frac << (32 - DBL_SHIFT)) | (j >> DBL_SHIFT); f2 = j << (32 - DBL_SHIFT); frac |= j; FP_TOF(exp, DBL_EXP_BIAS, frac, f0, f1, f2, 0); } /* * 128-bit extended -> fpn. */ int __fpu_qtof(fp, i, j, k, l) struct fpn *fp; u_int i, j, k, l; { int exp; u_int frac, f0, f1, f2, f3; #define EXT_SHIFT (-(EXT_FRACBITS - 3 * 32 - FP_LG)) /* left shift! */ /* * Note that ext and fpn `line up', hence no shifting needed. */ exp = (i >> (32 - 1 - EXT_EXPBITS)) & mask(EXT_EXPBITS); frac = i & mask(EXT_FRACBITS - 3 * 32); f0 = (frac << EXT_SHIFT) | (j >> (32 - EXT_SHIFT)); f1 = (j << EXT_SHIFT) | (k >> (32 - EXT_SHIFT)); f2 = (k << EXT_SHIFT) | (l >> (32 - EXT_SHIFT)); f3 = l << EXT_SHIFT; frac |= j | k | l; FP_TOF(exp, EXT_EXP_BIAS, frac, f0, f1, f2, f3); } #if 0 /* __fpu_explode is unused */ /* * Explode the contents of a / regpair / regquad. * If the input is a signalling NaN, an NV (invalid) exception * will be set. (Note that nothing but NV can occur until ALU * operations are performed.) */ void __fpu_explode(fe, fp, type, reg) struct fpemu *fe; struct fpn *fp; int type, reg; { u_int32_t s = 0/* XXX gcc */, *sp; u_int64_t l[2]; if (type == FTYPE_LNG || type == FTYPE_DBL || type == FTYPE_EXT) { l[0] = __fpu_getreg64(reg & ~1); sp = (u_int32_t *)l; fp->fp_sign = sp[0] >> 31; fp->fp_sticky = 0; switch (type) { case FTYPE_LNG: s = __fpu_xtof(fp, l[0]); break; case FTYPE_DBL: s = __fpu_dtof(fp, sp[0], sp[1]); break; case FTYPE_EXT: l[1] = __fpu_getreg64((reg & ~1) + 2); s = __fpu_qtof(fp, sp[0], sp[1], sp[2], sp[3]); break; default: #ifdef DIAGNOSTIC __utrap_panic("fpu_explode"); #endif break; } } else { #ifdef DIAGNOSTIC if (type != FTYPE_SNG) __utrap_panic("fpu_explode"); #endif s = __fpu_getreg32(reg); fp->fp_sign = s >> 31; fp->fp_sticky = 0; s = __fpu_stof(fp, s); } if (s == FPC_QNAN && (fp->fp_mant[0] & FP_QUIETBIT) == 0) { /* * Input is a signalling NaN. All operations that return * an input NaN operand put it through a ``NaN conversion'', * which basically just means ``turn on the quiet bit''. * We do this here so that all NaNs internally look quiet * (we can tell signalling ones by their class). */ fp->fp_mant[0] |= FP_QUIETBIT; fe->fe_cx = FSR_NV; /* assert invalid operand */ s = FPC_SNAN; } fp->fp_class = s; DPRINTF(FPE_REG, ("fpu_explode: %%%c%d => ", (type == FTYPE_LNG) ? 'x' : ((type == FTYPE_INT) ? 'i' : ((type == FTYPE_SNG) ? 's' : ((type == FTYPE_DBL) ? 'd' : ((type == FTYPE_EXT) ? 'q' : '?')))), reg)); DUMPFPN(FPE_REG, fp); DPRINTF(FPE_REG, ("\n")); } #endif
