243 lines
7.3 KiB
ArmAsm
243 lines
7.3 KiB
ArmAsm
/*
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* Copyright (c) 1987 Regents of the University of California.
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by the University of
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* California, Berkeley and its contributors.
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* 4. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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.data
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.align 2
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;_sccsid:
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; .asciz "from: @(#)support.s 5.6 (ucb.elefunt) 10/9/90"
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_rcsid:
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.asciz "$Id: support.s,v 1.1 1993/08/14 13:44:02 mycroft Exp $"
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/*
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* copysign(x,y),
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* logb(x),
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* scalb(x,N),
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* finite(x),
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* drem(x,y),
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* Coded in vax assembly language by K. C. Ng 4/9/85.
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* Re-coded in tahoe assembly language by Z. Alex Liu 7/13/87.
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*/
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/*
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* double copysign(x,y)
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* double x,y;
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*/
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.globl _copysign
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.text
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.align 2
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_copysign:
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.word 0x0004 # save r2
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movl 8(fp),r1
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movl 4(fp),r0 # r0:r1 = x
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andl3 $0x7f800000,r0,r2 # r2 = biased exponent of x
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beql 1f # if 0 or reserved op then return x
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andl3 $0x80000000,12(fp),r2 # r2 = sign bit of y at bit-31
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andl2 $0x7fffffff,r0 # replace x by |x|
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orl2 r2,r0 # copy the sign bit of y to x
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1: ret
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/*
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* double logb(x)
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* double x;
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*/
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.globl _logb
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.text
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.align 2
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_logb:
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.word 0x0000 # save nothing
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andl3 $0x7f800000,4(fp),r0 # r0[b23:b30] = biased exponent of x
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beql 1f
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shrl $23,r0,r0 # r0[b0:b7] = biased exponent of x
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subl2 $129,r0 # r0 = unbiased exponent of x
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cvld r0 # acc = unbiased exponent of x (double)
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std r0 # r0 = unbiased exponent of x (double)
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ret
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1: movl 8(fp),r1 # 8(fp) must be moved first
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movl 4(fp),r0 # r0:r1 = x (zero or reserved op)
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blss 2f # simply return if reserved op
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movl $0xfe000000,r1
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movl $0xcfffffff,r0 # -2147483647.0
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2: ret
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/*
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* long finite(x)
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* double x;
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*/
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.globl _finite
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.text
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.align 2
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_finite:
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.word 0x0000 # save nothing
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andl3 $0xff800000,4(fp),r0 # r0 = sign of x & its biased exponent
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cmpl r0,$0x80000000 # is x a reserved op?
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beql 1f # if so, return FALSE (0)
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movl $1,r0 # else return TRUE (1)
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ret
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1: clrl r0
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ret
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/*
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* double scalb(x,N)
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* double x; int N;
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*/
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.globl _scalb
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.set ERANGE,34
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.text
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.align 2
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_scalb:
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.word 0x000c # save r2-r3
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movl 8(fp),r1
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movl 4(fp),r0 # r0:r1 = x (-128 <= Ex <= 126)
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andl3 $0x7f800000,r0,r3 # r3[b23:b30] = biased exponent of x
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beql 1f # is x a 0 or a reserved operand?
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movl 12(fp),r2 # r2 = N
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cmpl r2,$0xff # if N >= 255
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bgeq 2f # then the result must overflow
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cmpl r2,$-0xff # if N <= -255
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bleq 3f # then the result must underflow
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shrl $23,r3,r3 # r3[b0:b7] = biased exponent of x
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addl2 r2,r3 # r3 = biased exponent of the result
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bleq 3f # if <= 0 then the result underflows
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cmpl r3,$0x100 # if >= 256 then the result overflows
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bgeq 2f
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shll $23,r3,r3 # r3[b23:b30] = biased exponent of res.
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andl2 $0x807fffff,r0
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orl2 r3,r0 # r0:r1 = x*2^N
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1: ret
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2: pushl $ERANGE # if the result would overflow
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callf $8,_infnan # and _infnan returns
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andl3 $0x80000000,4(fp),r2 # get the sign of input arg
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orl2 r2,r0 # re-attach the sign to r0:r1
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ret
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3: clrl r1 # if the result would underflow
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clrl r0 # then return 0
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ret
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/*
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* double drem(x,y)
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* double x,y;
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* Returns x-n*y where n=[x/y] rounded (to even in the half way case).
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*/
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.globl _drem
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.set EDOM,33
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.text
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.align 2
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_drem:
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.word 0x1ffc # save r2-r12
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movl 16(fp),r3
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movl 12(fp),r2 # r2:r3 = y
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movl 8(fp),r1
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movl 4(fp),r0 # r0:r1 = x
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andl3 $0xff800000,r0,r4
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cmpl r4,$0x80000000 # is x a reserved operand?
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beql 1f # if yes then propagate x and return
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andl3 $0xff800000,r2,r4
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cmpl r4,$0x80000000 # is y a reserved operand?
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bneq 2f
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movl r3,r1
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movl r2,r0 # if yes then propagate y and return
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1: ret
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2: tstl r4 # is y a 0?
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bneq 3f
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pushl $EDOM # if so then generate reserved op fault
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callf $8,_infnan
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ret
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3: andl2 $0x7fffffff,r2 # r2:r3 = y <- |y|
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clrl r12 # r12 = nx := 0
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cmpl r2,$0x1c800000 # Ey ? 57
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bgtr 4f # if Ey > 57 goto 4
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addl2 $0x1c800000,r2 # scale up y by 2**57
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movl $0x1c800000,r12 # r12[b23:b30] = nx = 57
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4: pushl r12 # pushed onto stack: nf := nx
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andl3 $0x80000000,r0,-(sp) # pushed onto stack: sign of x
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andl2 $0x7fffffff,r0 # r0:r1 = x <- |x|
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movl r3,r11 # r10:r11 = y1 = y w/ last 27 bits 0
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andl3 $0xf8000000,r10,r11 # clear last 27 bits of y1
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Loop: cmpd2 r0,r2 # x ? y
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bleq 6f # if x <= y goto 6
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/* # begin argument reduction */
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movl r3,r5
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movl r2,r4 # r4:r5 = t = y
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movl r11,r7
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movl r10,r6 # r6:r7 = t1 = y1
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andl3 $0x7f800000,r0,r8 # r8[b23:b30] = Ex:biased exponent of x
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andl3 $0x7f800000,r2,r9 # r9[b23:b30] = Ey:biased exponent of y
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subl2 r9,r8 # r8[b23:b30] = Ex-Ey
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subl2 $0x0c800000,r8 # r8[b23:b30] = k = Ex-Ey-25
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blss 5f # if k < 0 goto 5
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addl2 r8,r4 # t += k
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addl2 r8,r6 # t1 += k, scale up t and t1
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5: ldd r0 # acc = x
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divd r4 # acc = x/t
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cvdl r8 # r8 = n = [x/t] truncated
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cvld r8 # acc = dble(n)
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std r8 # r8:r9 = dble(n)
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ldd r4 # acc = t
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subd r6 # acc = t-t1
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muld r8 # acc = n*(t-t1)
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std r4 # r4:r5 = n*(t-t1)
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ldd r6 # acc = t1
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muld r8 # acc = n*t1
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subd r0 # acc = n*t1-x
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negd # acc = x-n*t1
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subd r4 # acc = (x-n*t1)-n*(t-t1)
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std r0 # r0:r1 = (x-n*t1)-n*(t-t1)
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brb Loop
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6: movl r12,r6 # r6 = nx
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beql 7f # if nx == 0 goto 7
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addl2 r6,r0 # x <- x*2**57:scale x up by nx
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clrl r12 # clear nx
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brb Loop
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7: movl r3,r5
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movl r2,r4 # r4:r5 = y
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subl2 $0x800000,r4 # r4:r5 = y/2
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cmpd2 r0,r4 # x ? y/2
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blss 9f # if x < y/2 goto 9
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bgtr 8f # if x > y/2 goto 8
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ldd r8 # acc = dble(n)
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cvdl r8 # r8 = ifix(dble(n))
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bbc $0,r8,9f # if the last bit is zero, goto 9
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8: ldd r0 # acc = x
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subd r2 # acc = x-y
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std r0 # r0:r1 = x-y
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9: xorl2 (sp)+,r0 # x^sign (exclusive or)
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movl (sp)+,r6 # r6 = nf
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andl3 $0x7f800000,r0,r8 # r8 = biased exponent of x
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andl2 $0x807fffff,r0 # r0 = x w/ exponent zapped
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subl2 r6,r8 # r8 = Ex-nf
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bgtr 0f # if Ex-nf > 0 goto 0
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clrl r8 # clear r8
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clrl r0
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clrl r1 # x underflows to zero
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0: orl2 r8,r0 # put r8 into x's exponent field
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ret
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