n_support.S revision 1.1
1 /* $NetBSD: n_support.S,v 1.1 1995/10/10 23:40:30 ragge 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. All advertising materials mentioning features or use of this software 15 * must display the following acknowledgement: 16 * This product includes software developed by the University of 17 * California, Berkeley and its contributors. 18 * 4. Neither the name of the University nor the names of its contributors 19 * may be used to endorse or promote products derived from this software 20 * without specific prior written permission. 21 * 22 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 25 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 32 * SUCH DAMAGE. 33 * 34 * @(#)support.s 8.1 (Berkeley) 6/4/93 35 */ 36 .data 37 .align 2 38 _sccsid: 39 .asciz "@(#)support.s 1.3 (Berkeley) 8/21/85; 8.1 (ucb.elefunt) 6/4/93" 40 41 /* 42 * copysign(x,y), 43 * logb(x), 44 * scalb(x,N), 45 * finite(x), 46 * drem(x,y), 47 * Coded in vax assembly language by K.C. Ng, 3/14/85. 48 * Revised by K.C. Ng on 4/9/85. 49 */ 50 51 /* 52 * double copysign(x,y) 53 * double x,y; 54 */ 55 .globl _copysign 56 .text 57 .align 1 58 _copysign: 59 .word 0x4 60 movq 4(ap),r0 # load x into r0 61 bicw3 $0x807f,r0,r2 # mask off the exponent of x 62 beql Lz # if zero or reserved op then return x 63 bicw3 $0x7fff,12(ap),r2 # copy the sign bit of y into r2 64 bicw2 $0x8000,r0 # replace x by |x| 65 bisw2 r2,r0 # copy the sign bit of y to x 66 Lz: ret 67 68 /* 69 * double logb(x) 70 * double x; 71 */ 72 .globl _logb 73 .text 74 .align 1 75 _logb: 76 .word 0x0 77 bicl3 $0xffff807f,4(ap),r0 # mask off the exponent of x 78 beql Ln 79 ashl $-7,r0,r0 # get the bias exponent 80 subl2 $129,r0 # get the unbias exponent 81 cvtld r0,r0 # return the answer in double 82 ret 83 Ln: movq 4(ap),r0 # r0:1 = x (zero or reserved op) 84 bneq 1f # simply return if reserved op 85 movq $0x0000fe00ffffcfff,r0 # -2147483647.0 86 1: ret 87 88 /* 89 * long finite(x) 90 * double x; 91 */ 92 .globl _finite 93 .text 94 .align 1 95 _finite: 96 .word 0x0000 97 bicw3 $0x7f,4(ap),r0 # mask off the mantissa 98 cmpw r0,$0x8000 # to see if x is the reserved op 99 beql 1f # if so, return FALSE (0) 100 movl $1,r0 # else return TRUE (1) 101 ret 102 1: clrl r0 103 ret 104 105 /* 106 * double scalb(x,N) 107 * double x; double N; 108 */ 109 .globl _scalb 110 .set ERANGE,34 111 .text 112 .align 1 113 _scalb: 114 .word 0x3c 115 movq 4(ap),r0 116 bicl3 $0xffff807f,r0,r3 117 beql ret1 # 0 or reserved operand 118 movq 12(ap),r4 119 cvtdl r4, r2 120 cmpl r2,$0x12c 121 bgeq ovfl 122 cmpl r2,$-0x12c 123 bleq unfl 124 ashl $7,r2,r2 125 addl2 r2,r3 126 bleq unfl 127 cmpl r3,$0x8000 128 bgeq ovfl 129 addl2 r2,r0 130 ret 131 ovfl: pushl $ERANGE 132 calls $1,_infnan # if it returns 133 bicw3 $0x7fff,4(ap),r2 # get the sign of input arg 134 bisw2 r2,r0 # re-attach the sign to r0/1 135 ret 136 unfl: movq $0,r0 137 ret1: ret 138 139 /* 140 * DREM(X,Y) 141 * RETURN X REM Y =X-N*Y, N=[X/Y] ROUNDED (ROUNDED TO EVEN IN THE HALF WAY CASE) 142 * DOUBLE PRECISION (VAX D format 56 bits) 143 * CODED IN VAX ASSEMBLY LANGUAGE BY K.C. NG, 4/8/85. 144 */ 145 .globl _drem 146 .set EDOM,33 147 .text 148 .align 1 149 _drem: 150 .word 0xffc 151 subl2 $12,sp 152 movq 4(ap),r0 #r0=x 153 movq 12(ap),r2 #r2=y 154 jeql Rop #if y=0 then generate reserved op fault 155 bicw3 $0x007f,r0,r4 #check if x is Rop 156 cmpw r4,$0x8000 157 jeql Ret #if x is Rop then return Rop 158 bicl3 $0x007f,r2,r4 #check if y is Rop 159 cmpw r4,$0x8000 160 jeql Ret #if y is Rop then return Rop 161 bicw2 $0x8000,r2 #y := |y| 162 movw $0,-4(fp) #-4(fp) = nx := 0 163 cmpw r2,$0x1c80 #yexp ? 57 164 bgtr C1 #if yexp > 57 goto C1 165 addw2 $0x1c80,r2 #scale up y by 2**57 166 movw $0x1c80,-4(fp) #nx := 57 (exponent field) 167 C1: 168 movw -4(fp),-8(fp) #-8(fp) = nf := nx 169 bicw3 $0x7fff,r0,-12(fp) #-12(fp) = sign of x 170 bicw2 $0x8000,r0 #x := |x| 171 movq r2,r10 #y1 := y 172 bicl2 $0xffff07ff,r11 #clear the last 27 bits of y1 173 loop: 174 cmpd r0,r2 #x ? y 175 bleq E1 #if x <= y goto E1 176 /* begin argument reduction */ 177 movq r2,r4 #t =y 178 movq r10,r6 #t1=y1 179 bicw3 $0x807f,r0,r8 #xexp= exponent of x 180 bicw3 $0x807f,r2,r9 #yexp= exponent fo y 181 subw2 r9,r8 #xexp-yexp 182 subw2 $0x0c80,r8 #k=xexp-yexp-25(exponent bit field) 183 blss C2 #if k<0 goto C2 184 addw2 r8,r4 #t +=k 185 addw2 r8,r6 #t1+=k, scale up t and t1 186 C2: 187 divd3 r4,r0,r8 #x/t 188 cvtdl r8,r8 #n=[x/t] truncated 189 cvtld r8,r8 #float(n) 190 subd2 r6,r4 #t:=t-t1 191 muld2 r8,r4 #n*(t-t1) 192 muld2 r8,r6 #n*t1 193 subd2 r6,r0 #x-n*t1 194 subd2 r4,r0 #(x-n*t1)-n*(t-t1) 195 brb loop 196 E1: 197 movw -4(fp),r6 #r6=nx 198 beql C3 #if nx=0 goto C3 199 addw2 r6,r0 #x:=x*2**57 scale up x by nx 200 movw $0,-4(fp) #clear nx 201 brb loop 202 C3: 203 movq r2,r4 #r4 = y 204 subw2 $0x80,r4 #r4 = y/2 205 cmpd r0,r4 #x:y/2 206 blss E2 #if x < y/2 goto E2 207 bgtr C4 #if x > y/2 goto C4 208 cvtdl r8,r8 #ifix(float(n)) 209 blbc r8,E2 #if the last bit is zero, goto E2 210 C4: 211 subd2 r2,r0 #x-y 212 E2: 213 xorw2 -12(fp),r0 #x^sign (exclusive or) 214 movw -8(fp),r6 #r6=nf 215 bicw3 $0x807f,r0,r8 #r8=exponent of x 216 bicw2 $0x7f80,r0 #clear the exponent of x 217 subw2 r6,r8 #r8=xexp-nf 218 bgtr C5 #if xexp-nf is positive goto C5 219 movw $0,r8 #clear r8 220 movq $0,r0 #x underflow to zero 221 C5: 222 bisw2 r8,r0 /* put r8 into x's exponent field */ 223 ret 224 Rop: #Reserved operand 225 pushl $EDOM 226 calls $1,_infnan #generate reserved op fault 227 ret 228 Ret: 229 movq $0x8000,r0 #propagate reserved op 230 ret 231
Indexes created Tue Sep 30 17:09:57 GMT 2025