1/* 2 * Copyright (c) 1985, 1993 3 * The Regents of the University of California. All rights reserved. 4 * 5 * %sccs.include.redist.c% 6 * 7 * @(#)support.s 8.1 (Berkeley) 06/04/93 8 */ 9 .data 10 .align 2 11_sccsid: 12.asciz "@(#)support.s 1.3 (Berkeley) 8/21/85; 8.1 (ucb.elefunt) 06/04/93" 13 14/* 15 * copysign(x,y), 16 * logb(x), 17 * scalb(x,N), 18 * finite(x), 19 * drem(x,y), 20 * Coded in vax assembly language by K.C. Ng, 3/14/85. 21 * Revised by K.C. Ng on 4/9/85. 22 */ 23 24/* 25 * double copysign(x,y) 26 * double x,y; 27 */ 28 .globl _copysign 29 .text 30 .align 1 31_copysign: 32 .word 0x4 33 movq 4(ap),r0 # load x into r0 34 bicw3 $0x807f,r0,r2 # mask off the exponent of x 35 beql Lz # if zero or reserved op then return x 36 bicw3 $0x7fff,12(ap),r2 # copy the sign bit of y into r2 37 bicw2 $0x8000,r0 # replace x by |x| 38 bisw2 r2,r0 # copy the sign bit of y to x 39Lz: ret 40 41/* 42 * double logb(x) 43 * double x; 44 */ 45 .globl _logb 46 .text 47 .align 1 48_logb: 49 .word 0x0 50 bicl3 $0xffff807f,4(ap),r0 # mask off the exponent of x 51 beql Ln 52 ashl $-7,r0,r0 # get the bias exponent 53 subl2 $129,r0 # get the unbias exponent 54 cvtld r0,r0 # return the answer in double 55 ret 56Ln: movq 4(ap),r0 # r0:1 = x (zero or reserved op) 57 bneq 1f # simply return if reserved op 58 movq $0x0000fe00ffffcfff,r0 # -2147483647.0 591: ret 60 61/* 62 * long finite(x) 63 * double x; 64 */ 65 .globl _finite 66 .text 67 .align 1 68_finite: 69 .word 0x0000 70 bicw3 $0x7f,4(ap),r0 # mask off the mantissa 71 cmpw r0,$0x8000 # to see if x is the reserved op 72 beql 1f # if so, return FALSE (0) 73 movl $1,r0 # else return TRUE (1) 74 ret 751: clrl r0 76 ret 77 78/* 79 * double scalb(x,N) 80 * double x; int N; 81 */ 82 .globl _scalb 83 .set ERANGE,34 84 .text 85 .align 1 86_scalb: 87 .word 0xc 88 movq 4(ap),r0 89 bicl3 $0xffff807f,r0,r3 90 beql ret1 # 0 or reserved operand 91 movl 12(ap),r2 92 cmpl r2,$0x12c 93 bgeq ovfl 94 cmpl r2,$-0x12c 95 bleq unfl 96 ashl $7,r2,r2 97 addl2 r2,r3 98 bleq unfl 99 cmpl r3,$0x8000 100 bgeq ovfl 101 addl2 r2,r0 102 ret 103ovfl: pushl $ERANGE 104 calls $1,_infnan # if it returns 105 bicw3 $0x7fff,4(ap),r2 # get the sign of input arg 106 bisw2 r2,r0 # re-attach the sign to r0/1 107 ret 108unfl: movq $0,r0 109ret1: ret 110 111/* 112 * DREM(X,Y) 113 * RETURN X REM Y =X-N*Y, N=[X/Y] ROUNDED (ROUNDED TO EVEN IN THE HALF WAY CASE) 114 * DOUBLE PRECISION (VAX D format 56 bits) 115 * CODED IN VAX ASSEMBLY LANGUAGE BY K.C. NG, 4/8/85. 116 */ 117 .globl _drem 118 .set EDOM,33 119 .text 120 .align 1 121_drem: 122 .word 0xffc 123 subl2 $12,sp 124 movq 4(ap),r0 #r0=x 125 movq 12(ap),r2 #r2=y 126 jeql Rop #if y=0 then generate reserved op fault 127 bicw3 $0x007f,r0,r4 #check if x is Rop 128 cmpw r4,$0x8000 129 jeql Ret #if x is Rop then return Rop 130 bicl3 $0x007f,r2,r4 #check if y is Rop 131 cmpw r4,$0x8000 132 jeql Ret #if y is Rop then return Rop 133 bicw2 $0x8000,r2 #y := |y| 134 movw $0,-4(fp) #-4(fp) = nx := 0 135 cmpw r2,$0x1c80 #yexp ? 57 136 bgtr C1 #if yexp > 57 goto C1 137 addw2 $0x1c80,r2 #scale up y by 2**57 138 movw $0x1c80,-4(fp) #nx := 57 (exponent field) 139C1: 140 movw -4(fp),-8(fp) #-8(fp) = nf := nx 141 bicw3 $0x7fff,r0,-12(fp) #-12(fp) = sign of x 142 bicw2 $0x8000,r0 #x := |x| 143 movq r2,r10 #y1 := y 144 bicl2 $0xffff07ff,r11 #clear the last 27 bits of y1 145loop: 146 cmpd r0,r2 #x ? y 147 bleq E1 #if x <= y goto E1 148 /* begin argument reduction */ 149 movq r2,r4 #t =y 150 movq r10,r6 #t1=y1 151 bicw3 $0x807f,r0,r8 #xexp= exponent of x 152 bicw3 $0x807f,r2,r9 #yexp= exponent fo y 153 subw2 r9,r8 #xexp-yexp 154 subw2 $0x0c80,r8 #k=xexp-yexp-25(exponent bit field) 155 blss C2 #if k<0 goto C2 156 addw2 r8,r4 #t +=k 157 addw2 r8,r6 #t1+=k, scale up t and t1 158C2: 159 divd3 r4,r0,r8 #x/t 160 cvtdl r8,r8 #n=[x/t] truncated 161 cvtld r8,r8 #float(n) 162 subd2 r6,r4 #t:=t-t1 163 muld2 r8,r4 #n*(t-t1) 164 muld2 r8,r6 #n*t1 165 subd2 r6,r0 #x-n*t1 166 subd2 r4,r0 #(x-n*t1)-n*(t-t1) 167 brb loop 168E1: 169 movw -4(fp),r6 #r6=nx 170 beql C3 #if nx=0 goto C3 171 addw2 r6,r0 #x:=x*2**57 scale up x by nx 172 movw $0,-4(fp) #clear nx 173 brb loop 174C3: 175 movq r2,r4 #r4 = y 176 subw2 $0x80,r4 #r4 = y/2 177 cmpd r0,r4 #x:y/2 178 blss E2 #if x < y/2 goto E2 179 bgtr C4 #if x > y/2 goto C4 180 cvtdl r8,r8 #ifix(float(n)) 181 blbc r8,E2 #if the last bit is zero, goto E2 182C4: 183 subd2 r2,r0 #x-y 184E2: 185 xorw2 -12(fp),r0 #x^sign (exclusive or) 186 movw -8(fp),r6 #r6=nf 187 bicw3 $0x807f,r0,r8 #r8=exponent of x 188 bicw2 $0x7f80,r0 #clear the exponent of x 189 subw2 r6,r8 #r8=xexp-nf 190 bgtr C5 #if xexp-nf is positive goto C5 191 movw $0,r8 #clear r8 192 movq $0,r0 #x underflow to zero 193C5: 194 bisw2 r8,r0 #put r8 into x's exponent field 195 ret 196Rop: #Reserved operand 197 pushl $EDOM 198 calls $1,_infnan #generate reserved op fault 199 ret 200Ret: 201 movq $0x8000,r0 #propagate reserved op 202 ret 203