NetBSD/lib/libm/tahoe/support.S

243 lines
7.3 KiB
ArmAsm

/*
* Copyright (c) 1987 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.
*/
.data
.align 2
;_sccsid:
; .asciz "from: @(#)support.s 5.6 (ucb.elefunt) 10/9/90"
_rcsid:
.asciz "$Id: support.S,v 1.1 1993/08/14 13:44:02 mycroft Exp $"
/*
* copysign(x,y),
* logb(x),
* scalb(x,N),
* finite(x),
* drem(x,y),
* Coded in vax assembly language by K. C. Ng 4/9/85.
* Re-coded in tahoe assembly language by Z. Alex Liu 7/13/87.
*/
/*
* double copysign(x,y)
* double x,y;
*/
.globl _copysign
.text
.align 2
_copysign:
.word 0x0004 # save r2
movl 8(fp),r1
movl 4(fp),r0 # r0:r1 = x
andl3 $0x7f800000,r0,r2 # r2 = biased exponent of x
beql 1f # if 0 or reserved op then return x
andl3 $0x80000000,12(fp),r2 # r2 = sign bit of y at bit-31
andl2 $0x7fffffff,r0 # replace x by |x|
orl2 r2,r0 # copy the sign bit of y to x
1: ret
/*
* double logb(x)
* double x;
*/
.globl _logb
.text
.align 2
_logb:
.word 0x0000 # save nothing
andl3 $0x7f800000,4(fp),r0 # r0[b23:b30] = biased exponent of x
beql 1f
shrl $23,r0,r0 # r0[b0:b7] = biased exponent of x
subl2 $129,r0 # r0 = unbiased exponent of x
cvld r0 # acc = unbiased exponent of x (double)
std r0 # r0 = unbiased exponent of x (double)
ret
1: movl 8(fp),r1 # 8(fp) must be moved first
movl 4(fp),r0 # r0:r1 = x (zero or reserved op)
blss 2f # simply return if reserved op
movl $0xfe000000,r1
movl $0xcfffffff,r0 # -2147483647.0
2: ret
/*
* long finite(x)
* double x;
*/
.globl _finite
.text
.align 2
_finite:
.word 0x0000 # save nothing
andl3 $0xff800000,4(fp),r0 # r0 = sign of x & its biased exponent
cmpl r0,$0x80000000 # is x a 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 2
_scalb:
.word 0x000c # save r2-r3
movl 8(fp),r1
movl 4(fp),r0 # r0:r1 = x (-128 <= Ex <= 126)
andl3 $0x7f800000,r0,r3 # r3[b23:b30] = biased exponent of x
beql 1f # is x a 0 or a reserved operand?
movl 12(fp),r2 # r2 = N
cmpl r2,$0xff # if N >= 255
bgeq 2f # then the result must overflow
cmpl r2,$-0xff # if N <= -255
bleq 3f # then the result must underflow
shrl $23,r3,r3 # r3[b0:b7] = biased exponent of x
addl2 r2,r3 # r3 = biased exponent of the result
bleq 3f # if <= 0 then the result underflows
cmpl r3,$0x100 # if >= 256 then the result overflows
bgeq 2f
shll $23,r3,r3 # r3[b23:b30] = biased exponent of res.
andl2 $0x807fffff,r0
orl2 r3,r0 # r0:r1 = x*2^N
1: ret
2: pushl $ERANGE # if the result would overflow
callf $8,_infnan # and _infnan returns
andl3 $0x80000000,4(fp),r2 # get the sign of input arg
orl2 r2,r0 # re-attach the sign to r0:r1
ret
3: clrl r1 # if the result would underflow
clrl r0 # then return 0
ret
/*
* double drem(x,y)
* double x,y;
* Returns x-n*y where n=[x/y] rounded (to even in the half way case).
*/
.globl _drem
.set EDOM,33
.text
.align 2
_drem:
.word 0x1ffc # save r2-r12
movl 16(fp),r3
movl 12(fp),r2 # r2:r3 = y
movl 8(fp),r1
movl 4(fp),r0 # r0:r1 = x
andl3 $0xff800000,r0,r4
cmpl r4,$0x80000000 # is x a reserved operand?
beql 1f # if yes then propagate x and return
andl3 $0xff800000,r2,r4
cmpl r4,$0x80000000 # is y a reserved operand?
bneq 2f
movl r3,r1
movl r2,r0 # if yes then propagate y and return
1: ret
2: tstl r4 # is y a 0?
bneq 3f
pushl $EDOM # if so then generate reserved op fault
callf $8,_infnan
ret
3: andl2 $0x7fffffff,r2 # r2:r3 = y <- |y|
clrl r12 # r12 = nx := 0
cmpl r2,$0x1c800000 # Ey ? 57
bgtr 4f # if Ey > 57 goto 4
addl2 $0x1c800000,r2 # scale up y by 2**57
movl $0x1c800000,r12 # r12[b23:b30] = nx = 57
4: pushl r12 # pushed onto stack: nf := nx
andl3 $0x80000000,r0,-(sp) # pushed onto stack: sign of x
andl2 $0x7fffffff,r0 # r0:r1 = x <- |x|
movl r3,r11 # r10:r11 = y1 = y w/ last 27 bits 0
andl3 $0xf8000000,r10,r11 # clear last 27 bits of y1
Loop: cmpd2 r0,r2 # x ? y
bleq 6f # if x <= y goto 6
/* # begin argument reduction */
movl r3,r5
movl r2,r4 # r4:r5 = t = y
movl r11,r7
movl r10,r6 # r6:r7 = t1 = y1
andl3 $0x7f800000,r0,r8 # r8[b23:b30] = Ex:biased exponent of x
andl3 $0x7f800000,r2,r9 # r9[b23:b30] = Ey:biased exponent of y
subl2 r9,r8 # r8[b23:b30] = Ex-Ey
subl2 $0x0c800000,r8 # r8[b23:b30] = k = Ex-Ey-25
blss 5f # if k < 0 goto 5
addl2 r8,r4 # t += k
addl2 r8,r6 # t1 += k, scale up t and t1
5: ldd r0 # acc = x
divd r4 # acc = x/t
cvdl r8 # r8 = n = [x/t] truncated
cvld r8 # acc = dble(n)
std r8 # r8:r9 = dble(n)
ldd r4 # acc = t
subd r6 # acc = t-t1
muld r8 # acc = n*(t-t1)
std r4 # r4:r5 = n*(t-t1)
ldd r6 # acc = t1
muld r8 # acc = n*t1
subd r0 # acc = n*t1-x
negd # acc = x-n*t1
subd r4 # acc = (x-n*t1)-n*(t-t1)
std r0 # r0:r1 = (x-n*t1)-n*(t-t1)
brb Loop
6: movl r12,r6 # r6 = nx
beql 7f # if nx == 0 goto 7
addl2 r6,r0 # x <- x*2**57:scale x up by nx
clrl r12 # clear nx
brb Loop
7: movl r3,r5
movl r2,r4 # r4:r5 = y
subl2 $0x800000,r4 # r4:r5 = y/2
cmpd2 r0,r4 # x ? y/2
blss 9f # if x < y/2 goto 9
bgtr 8f # if x > y/2 goto 8
ldd r8 # acc = dble(n)
cvdl r8 # r8 = ifix(dble(n))
bbc $0,r8,9f # if the last bit is zero, goto 9
8: ldd r0 # acc = x
subd r2 # acc = x-y
std r0 # r0:r1 = x-y
9: xorl2 (sp)+,r0 # x^sign (exclusive or)
movl (sp)+,r6 # r6 = nf
andl3 $0x7f800000,r0,r8 # r8 = biased exponent of x
andl2 $0x807fffff,r0 # r0 = x w/ exponent zapped
subl2 r6,r8 # r8 = Ex-nf
bgtr 0f # if Ex-nf > 0 goto 0
clrl r8 # clear r8
clrl r0
clrl r1 # x underflows to zero
0: orl2 r8,r0 # put r8 into x's exponent field
ret