n_support.S revision 1.6
1 /* $NetBSD: n_support.S,v 1.6 2003/08/07 16:44:45 agc Exp $ */ 2 /* 3 * Copyright (c) 1985, 1993 4 * The Regents of the University of California. All rights reserved. 5 * 6 * Redistribution and use in source and binary forms, with or without 7 * modification, are permitted provided that the following conditions 8 * are met: 9 * 1. Redistributions of source code must retain the above copyright 10 * notice, this list of conditions and the following disclaimer. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 3. Neither the name of the University nor the names of its contributors 15 * may be used to endorse or promote products derived from this software 16 * without specific prior written permission. 17 * 18 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 19 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 20 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 21 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 22 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 23 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 24 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 25 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 26 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 27 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 28 * SUCH DAMAGE. 29 * 30 * @(#)support.s 8.1 (Berkeley) 6/4/93 31 */ 32 #include <machine/asm.h> 33 34 .text 35 _sccsid: 36 .asciz "@(#)support.s\t1.3 (Berkeley) 8/21/85; 8.1 (ucb.elefunt) 6/4/93" 37 38 /* 39 * copysign(x,y), 40 * logb(x), 41 * scalb(x,N), 42 * finite(x), 43 * drem(x,y), 44 * Coded in vax assembly language by K.C. Ng, 3/14/85. 45 * Revised by K.C. Ng on 4/9/85. 46 */ 47 48 /* 49 * double copysign(double x,double y) 50 */ 51 52 ENTRY(copysign, 0) 53 movq 4(%ap),%r0 # load x into %r0 54 bicw3 $0x807f,%r0,%r2 # mask off the exponent of x 55 beql Lz # if zero or reserved op then return x 56 bicw3 $0x7fff,12(%ap),%r2 # copy the sign bit of y into %r2 57 bicw2 $0x8000,%r0 # replace x by |x| 58 bisw2 %r2,%r0 # copy the sign bit of y to x 59 Lz: ret 60 61 /* 62 * double logb(double x); 63 */ 64 ENTRY(logb, 0) 65 bicl3 $0xffff807f,4(%ap),%r0 # mask off the exponent of x 66 beql Ln 67 ashl $-7,%r0,%r0 # get the bias exponent 68 subl2 $129,%r0 # get the unbias exponent 69 cvtld %r0,%r0 # return the answer in double 70 ret 71 Ln: movq 4(%ap),%r0 # %r0:1 = x (zero or reserved op) 72 bneq 1f # simply return if reserved op 73 movq $0x0000fe00ffffcfff,%r0 # -2147483647.0 74 1: ret 75 76 /* 77 * long finite(double x); 78 */ 79 #ifndef __GFLOAT__ 80 .globl finitef 81 finitef = finite 82 #endif 83 ENTRY(finite, 0) 84 bicw3 $0x7f,4(%ap),%r0 # mask off the mantissa 85 cmpw %r0,$0x8000 # to see if x is the reserved op 86 beql 1f # if so, return FALSE (0) 87 movl $1,%r0 # else return TRUE (1) 88 ret 89 1: clrl %r0 90 ret 91 92 /* int isnan(double x); 93 */ 94 #if 0 95 ENTRY(isnan, 0) 96 clrl %r0 97 ret 98 #endif 99 100 /* int isnanf(float x); 101 */ 102 ENTRY(isnanf, 0) 103 clrl %r0 104 ret 105 106 /* 107 * double scalb(x,N) 108 * double x; double N; 109 */ 110 .set ERANGE,34 111 112 ENTRY(scalb, 0) 113 movq 4(%ap),%r0 114 bicl3 $0xffff807f,%r0,%r3 115 beql ret1 # 0 or reserved operand 116 movq 12(%ap),%r4 117 cvtdl %r4, %r2 118 cmpl %r2,$0x12c 119 bgeq ovfl 120 cmpl %r2,$-0x12c 121 bleq unfl 122 ashl $7,%r2,%r2 123 addl2 %r2,%r3 124 bleq unfl 125 cmpl %r3,$0x8000 126 bgeq ovfl 127 addl2 %r2,%r0 128 ret 129 ovfl: pushl $ERANGE 130 calls $1,_C_LABEL(infnan) # if it returns 131 bicw3 $0x7fff,4(%ap),%r2 # get the sign of input arg 132 bisw2 %r2,%r0 # re-attach the sign to %r0/1 133 ret 134 unfl: movq $0,%r0 135 ret1: ret 136 137 /* 138 * DREM(X,Y) 139 * RETURN X REM Y =X-N*Y, N=[X/Y] ROUNDED (ROUNDED TO EVEN IN THE HALF WAY CASE) 140 * DOUBLE PRECISION (VAX D format 56 bits) 141 * CODED IN VAX ASSEMBLY LANGUAGE BY K.C. NG, 4/8/85. 142 */ 143 .set EDOM,33 144 145 ENTRY(drem, 0x0fc0) 146 subl2 $12,%sp 147 movq 4(%ap),%r0 #%r0=x 148 movq 12(%ap),%r2 #%r2=y 149 jeql Rop #if y=0 then generate reserved op fault 150 bicw3 $0x007f,%r0,%r4 #check if x is Rop 151 cmpw %r4,$0x8000 152 jeql Ret #if x is Rop then return Rop 153 bicl3 $0x007f,%r2,%r4 #check if y is Rop 154 cmpw %r4,$0x8000 155 jeql Ret #if y is Rop then return Rop 156 bicw2 $0x8000,%r2 #y := |y| 157 movw $0,-4(%fp) #-4(%fp) = nx := 0 158 cmpw %r2,$0x1c80 #yexp ? 57 159 bgtr C1 #if yexp > 57 goto C1 160 addw2 $0x1c80,%r2 #scale up y by 2**57 161 movw $0x1c80,-4(%fp) #nx := 57 (exponent field) 162 C1: 163 movw -4(%fp),-8(%fp) #-8(%fp) = nf := nx 164 bicw3 $0x7fff,%r0,-12(%fp) #-12(%fp) = sign of x 165 bicw2 $0x8000,%r0 #x := |x| 166 movq %r2,%r10 #y1 := y 167 bicl2 $0xffff07ff,%r11 #clear the last 27 bits of y1 168 loop: 169 cmpd %r0,%r2 #x ? y 170 bleq E1 #if x <= y goto E1 171 /* begin argument reduction */ 172 movq %r2,%r4 #t =y 173 movq %r10,%r6 #t1=y1 174 bicw3 $0x807f,%r0,%r8 #xexp= exponent of x 175 bicw3 $0x807f,%r2,%r9 #yexp= exponent fo y 176 subw2 %r9,%r8 #xexp-yexp 177 subw2 $0x0c80,%r8 #k=xexp-yexp-25(exponent bit field) 178 blss C2 #if k<0 goto C2 179 addw2 %r8,%r4 #t +=k 180 addw2 %r8,%r6 #t1+=k, scale up t and t1 181 C2: 182 divd3 %r4,%r0,%r8 #x/t 183 cvtdl %r8,%r8 #n=[x/t] truncated 184 cvtld %r8,%r8 #float(n) 185 subd2 %r6,%r4 #t:=t-t1 186 muld2 %r8,%r4 #n*(t-t1) 187 muld2 %r8,%r6 #n*t1 188 subd2 %r6,%r0 #x-n*t1 189 subd2 %r4,%r0 #(x-n*t1)-n*(t-t1) 190 jbr loop 191 E1: 192 movw -4(%fp),%r6 #%r6=nx 193 beql C3 #if nx=0 goto C3 194 addw2 %r6,%r0 #x:=x*2**57 scale up x by nx 195 movw $0,-4(%fp) #clear nx 196 jbr loop 197 C3: 198 movq %r2,%r4 #%r4 = y 199 subw2 $0x80,%r4 #%r4 = y/2 200 cmpd %r0,%r4 #x:y/2 201 blss E2 #if x < y/2 goto E2 202 bgtr C4 #if x > y/2 goto C4 203 cvtdl %r8,%r8 #ifix(float(n)) 204 blbc %r8,E2 #if the last bit is zero, goto E2 205 C4: 206 subd2 %r2,%r0 #x-y 207 E2: 208 xorw2 -12(%fp),%r0 #x^sign (exclusive or) 209 movw -8(%fp),%r6 #%r6=nf 210 bicw3 $0x807f,%r0,%r8 #%r8=exponent of x 211 bicw2 $0x7f80,%r0 #clear the exponent of x 212 subw2 %r6,%r8 #%r8=xexp-nf 213 bgtr C5 #if xexp-nf is positive goto C5 214 movw $0,%r8 #clear %r8 215 movq $0,%r0 #x underflow to zero 216 C5: 217 bisw2 %r8,%r0 /* put %r8 into x's exponent field */ 218 ret 219 Rop: #Reserved operand 220 pushl $EDOM 221 calls $1,_C_LABEL(infnan) #generate reserved op fault 222 ret 223 Ret: 224 movq $0x8000,%r0 #propagate reserved op 225 ret 226
Indexes created Tue Sep 30 20:09:53 GMT 2025