4.4BSD/usr/src/lib/libm/vax/support.s
/*
* Copyright (c) 1985, 1993
* The Regents of the University of California. All rights reserved.
*
* 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.
*
* @(#)support.s 8.1 (Berkeley) 6/4/93
*/
.data
.align 2
_sccsid:
.asciz "@(#)support.s 1.3 (Berkeley) 8/21/85; 8.1 (ucb.elefunt) 6/4/93"
/*
* copysign(x,y),
* logb(x),
* scalb(x,N),
* finite(x),
* drem(x,y),
* Coded in vax assembly language by K.C. Ng, 3/14/85.
* Revised by K.C. Ng on 4/9/85.
*/
/*
* double copysign(x,y)
* double x,y;
*/
.globl _copysign
.text
.align 1
_copysign:
.word 0x4
movq 4(ap),r0 # load x into r0
bicw3 $0x807f,r0,r2 # mask off the exponent of x
beql Lz # if zero or reserved op then return x
bicw3 $0x7fff,12(ap),r2 # copy the sign bit of y into r2
bicw2 $0x8000,r0 # replace x by |x|
bisw2 r2,r0 # copy the sign bit of y to x
Lz: ret
/*
* double logb(x)
* double x;
*/
.globl _logb
.text
.align 1
_logb:
.word 0x0
bicl3 $0xffff807f,4(ap),r0 # mask off the exponent of x
beql Ln
ashl $-7,r0,r0 # get the bias exponent
subl2 $129,r0 # get the unbias exponent
cvtld r0,r0 # return the answer in double
ret
Ln: movq 4(ap),r0 # r0:1 = x (zero or reserved op)
bneq 1f # simply return if reserved op
movq $0x0000fe00ffffcfff,r0 # -2147483647.0
1: ret
/*
* long finite(x)
* double x;
*/
.globl _finite
.text
.align 1
_finite:
.word 0x0000
bicw3 $0x7f,4(ap),r0 # mask off the mantissa
cmpw r0,$0x8000 # to see if x is the reserved op
beql 1f # if so, return FALSE (0)
movl $1,r0 # else return TRUE (1)
ret
1: clrl r0
ret
/*
* double scalb(x,N)
* double x; int N;
*/
.globl _scalb
.set ERANGE,34
.text
.align 1
_scalb:
.word 0xc
movq 4(ap),r0
bicl3 $0xffff807f,r0,r3
beql ret1 # 0 or reserved operand
movl 12(ap),r2
cmpl r2,$0x12c
bgeq ovfl
cmpl r2,$-0x12c
bleq unfl
ashl $7,r2,r2
addl2 r2,r3
bleq unfl
cmpl r3,$0x8000
bgeq ovfl
addl2 r2,r0
ret
ovfl: pushl $ERANGE
calls $1,_infnan # if it returns
bicw3 $0x7fff,4(ap),r2 # get the sign of input arg
bisw2 r2,r0 # re-attach the sign to r0/1
ret
unfl: movq $0,r0
ret1: ret
/*
* DREM(X,Y)
* RETURN X REM Y =X-N*Y, N=[X/Y] ROUNDED (ROUNDED TO EVEN IN THE HALF WAY CASE)
* DOUBLE PRECISION (VAX D format 56 bits)
* CODED IN VAX ASSEMBLY LANGUAGE BY K.C. NG, 4/8/85.
*/
.globl _drem
.set EDOM,33
.text
.align 1
_drem:
.word 0xffc
subl2 $12,sp
movq 4(ap),r0 #r0=x
movq 12(ap),r2 #r2=y
jeql Rop #if y=0 then generate reserved op fault
bicw3 $0x007f,r0,r4 #check if x is Rop
cmpw r4,$0x8000
jeql Ret #if x is Rop then return Rop
bicl3 $0x007f,r2,r4 #check if y is Rop
cmpw r4,$0x8000
jeql Ret #if y is Rop then return Rop
bicw2 $0x8000,r2 #y := |y|
movw $0,-4(fp) #-4(fp) = nx := 0
cmpw r2,$0x1c80 #yexp ? 57
bgtr C1 #if yexp > 57 goto C1
addw2 $0x1c80,r2 #scale up y by 2**57
movw $0x1c80,-4(fp) #nx := 57 (exponent field)
C1:
movw -4(fp),-8(fp) #-8(fp) = nf := nx
bicw3 $0x7fff,r0,-12(fp) #-12(fp) = sign of x
bicw2 $0x8000,r0 #x := |x|
movq r2,r10 #y1 := y
bicl2 $0xffff07ff,r11 #clear the last 27 bits of y1
loop:
cmpd r0,r2 #x ? y
bleq E1 #if x <= y goto E1
/* begin argument reduction */
movq r2,r4 #t =y
movq r10,r6 #t1=y1
bicw3 $0x807f,r0,r8 #xexp= exponent of x
bicw3 $0x807f,r2,r9 #yexp= exponent fo y
subw2 r9,r8 #xexp-yexp
subw2 $0x0c80,r8 #k=xexp-yexp-25(exponent bit field)
blss C2 #if k<0 goto C2
addw2 r8,r4 #t +=k
addw2 r8,r6 #t1+=k, scale up t and t1
C2:
divd3 r4,r0,r8 #x/t
cvtdl r8,r8 #n=[x/t] truncated
cvtld r8,r8 #float(n)
subd2 r6,r4 #t:=t-t1
muld2 r8,r4 #n*(t-t1)
muld2 r8,r6 #n*t1
subd2 r6,r0 #x-n*t1
subd2 r4,r0 #(x-n*t1)-n*(t-t1)
brb loop
E1:
movw -4(fp),r6 #r6=nx
beql C3 #if nx=0 goto C3
addw2 r6,r0 #x:=x*2**57 scale up x by nx
movw $0,-4(fp) #clear nx
brb loop
C3:
movq r2,r4 #r4 = y
subw2 $0x80,r4 #r4 = y/2
cmpd r0,r4 #x:y/2
blss E2 #if x < y/2 goto E2
bgtr C4 #if x > y/2 goto C4
cvtdl r8,r8 #ifix(float(n))
blbc r8,E2 #if the last bit is zero, goto E2
C4:
subd2 r2,r0 #x-y
E2:
xorw2 -12(fp),r0 #x^sign (exclusive or)
movw -8(fp),r6 #r6=nf
bicw3 $0x807f,r0,r8 #r8=exponent of x
bicw2 $0x7f80,r0 #clear the exponent of x
subw2 r6,r8 #r8=xexp-nf
bgtr C5 #if xexp-nf is positive goto C5
movw $0,r8 #clear r8
movq $0,r0 #x underflow to zero
C5:
bisw2 r8,r0 #put r8 into x's exponent field
ret
Rop: #Reserved operand
pushl $EDOM
calls $1,_infnan #generate reserved op fault
ret
Ret:
movq $0x8000,r0 #propagate reserved op
ret