1 /* $NetBSD: fpu_int.c,v 1.5 2002/05/30 20:56:26 thorpej Exp $ */ 2 3 /* 4 * Copyright (c) 1995 Ken Nakata 5 * All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 17 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 18 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 19 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 20 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 21 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 22 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 23 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 24 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 25 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 26 * SUCH DAMAGE. 27 * 28 * @(#)fpu_int.c 29 */ 30 31 #include <sys/types.h> 32 33 #include <machine/reg.h> 34 35 #include "fpu_arith.h" 36 #include "fpu_emulate.h" 37 38 /* FINTRZ - always round to zero */ 39 struct fpn * 40 fpu_intrz(fe) 41 struct fpemu *fe; 42 { 43 register struct fpn *x = &fe->fe_f2; 44 register int sh, clr, mask, i; 45 46 /* special cases first */ 47 if (x->fp_class != FPC_NUM) { 48 return x; 49 } 50 /* when |x| < 1.0 */ 51 if (x->fp_exp < 0) { 52 x->fp_class = FPC_ZERO; 53 x->fp_mant[0] = x->fp_mant[1] = x->fp_mant[2] = 0; 54 return x; 55 } 56 57 /* real work */ 58 sh = FP_NMANT - 1 - x->fp_exp; 59 if (sh <= 0) { 60 return x; 61 } 62 63 clr = 2 - sh / 32; 64 mask = (0xffffffff << (sh % 32)); 65 66 for (i = 2; i > clr; i--) { 67 x->fp_mant[i] = 0; 68 } 69 x->fp_mant[i] &= mask; 70 71 return x; 72 } 73 74 /* FINT */ 75 struct fpn * 76 fpu_int(fe) 77 struct fpemu *fe; 78 { 79 register struct fpn *x = &fe->fe_f2; 80 register int rsh, lsh, wsh, i; 81 82 /* special cases first */ 83 if (x->fp_class != FPC_NUM) { 84 return x; 85 } 86 /* even if we have exponent == -1, we still have possiblity 87 that the result >= 1.0 when mantissa ~= 1.0 and rounded up */ 88 if (x->fp_exp < -1) { 89 x->fp_class = FPC_ZERO; 90 x->fp_mant[0] = x->fp_mant[1] = x->fp_mant[2] = 0; 91 return x; 92 } 93 94 /* real work */ 95 rsh = FP_NMANT - 1 - x->fp_exp; 96 if (rsh - FP_NG <= 0) { 97 return x; 98 } 99 100 fpu_shr(x, rsh - FP_NG); /* shift to the right */ 101 102 if (fpu_round(fe, x) == 1 /* rounded up */ && 103 x->fp_mant[2 - (FP_NMANT-rsh)/32] & (1 << ((FP_NMANT-rsh)%32)) 104 /* x >= 2.0 */) { 105 rsh--; /* reduce shift count by 1 */ 106 x->fp_exp++; /* adjust exponent */ 107 } 108 109 /* shift it back to the left */ 110 wsh = rsh / 32; 111 lsh = rsh % 32; 112 rsh = 32 - lsh; 113 for (i = 0; i + wsh < 2; i++) { 114 x->fp_mant[i] = (x->fp_mant[i+wsh] << lsh) | (x->fp_mant[i+wsh+1] >> rsh); 115 } 116 x->fp_mant[i] = (x->fp_mant[i+wsh] << lsh); 117 i++; 118 for (; i < 3; i++) { 119 x->fp_mant[i] = 0; 120 } 121 122 return x; 123 } 124