Windows NT 4.0 source code leak
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/*
* |-----------------------------------------------------------|
* | Copyright (c) 1991, 1990 MIPS Computer Systems, Inc. |
* | All Rights Reserved |
* |-----------------------------------------------------------|
* | Restricted Rights Legend |
* | Use, duplication, or disclosure by the Government is |
* | subject to restrictions as set forth in |
* | subparagraph (c)(1)(ii) of the Rights in Technical |
* | Data and Computer Software Clause of DFARS 252.227-7013. |
* | MIPS Computer Systems, Inc. |
* | 950 DeGuigne Avenue |
* | Sunnyvale, California 94088-3650, USA |
* |-----------------------------------------------------------|
*/
/* $Header: log.s,v 3000.5.1.4 91/08/14 09:31:27 zaineb Exp $ */
/* Algorithm from
"Table-driven Implementation of the Logarithm Functions for IEEE
Floating-Point Arithmetic", Peter Tang, Argonne National Laboratory,
February 2, 1989
Coded in MIPS assembler by Earl Killian.
*/
#include <kxmips.h>
#include <trans.h>
#include <fpieee.h>
#define loge 0.43429448190325182765
.extern _except1
.text
#undef FSIZE
#define FSIZE 48
.globl log
.ent log
log:
.frame sp, FSIZE, ra
subu sp, FSIZE
sw ra, FSIZE-4(sp)
.prologue 1
li t7, OP_LOG
b logmain
.globl log10
.aent log10
log10:
.frame sp, FSIZE, ra
subu sp, FSIZE
sw ra, FSIZE-4(sp)
.prologue 1
li t7, OP_LOG10
logmain:
/* argument in f12 */
.set noreorder
cfc1 t5, $31 /* save FCSR, set round to nearest */
ctc1 $0, $31 /* mode and no exceptions */
and t6, t5, -4
li.d $f10, 1.0644944589178595e+00 // ceil( exp( 1/16))
li.d $f16, 9.3941306281347570e-01 // floor(exp(-1/16))
c.ult.d $f12, $f10
mfc1 t0, $f13
bc1f 1f
srl t1, t0, 20
c.olt.d $f16, $f12
li.d $f10, 0.0
bc1t 5f
c.ule.d $f12, $f10
nop
bc1t 8f
nop
beq t1, 0, 4f
1: li t4, 2047
beq t1, t4, 7f
subu t1, 1023
sll t2, t1, 20
subu t2, t0, t2
mtc1 t2, $f13
.set reorder
2: ctc1 t6, $31
li.d $f16, 3.5184372088832000e+13 // 2^(53-8)
mtc1 t1, $f8
add.d $f18, $f12, $f16
la t4, _logtable
sub.d $f14, $f18, $f16
mfc1 t3, $f18
sub.d $f18, $f12, $f14
sll t3, 4
add.d $f14, $f12
l.d $f10, 128*16+0(t4) // log2head
div.d $f18, $f14
cvt.d.w $f8
l.d $f16, 128*16+8(t4) // log2trail
mul.d $f0, $f8, $f10
addu t3, t4
l.d $f4, -128*16+0(t3)
mul.d $f2, $f8, $f16
add.d $f0, $f4
l.d $f6, -128*16+8(t3)
add.d $f18, $f18
li.d $f10, 1.2500053168098584e-02
mul.d $f4, $f18, $f18
add.d $f2, $f6
li.d $f16, 8.3333333333039133e-02
mul.d $f6, $f4, $f10
add.d $f6, $f16
mul.d $f6, $f4
mul.d $f6, $f18
add.d $f6, $f2
add.d $f6, $f18
add.d $f0, $f6
j ret
4: /* denorm */
li.d $f10, 4.4942328371557898e+307 // 2^1022
mul.d $f12, $f10
mfc1 t0, $f13
srl t1, t0, 20
subu t1, 1023
sll t2, t1, 20
subu t2, t0, t2
mtc1 t2, $f13
addu t1, -1022
b 2b
5: /* exp(-1/16) < x < exp(1/16) */
/* use special approximation */
ctc1 t6, $31
li.d $f10, 1.0
sub.d $f14, $f12, $f10
add.d $f12, $f10
div.d $f12, $f10, $f12
cvt.s.d $f18, $f14
cvt.d.s $f18
sub.d $f8, $f14, $f18
add.d $f2, $f14, $f14
mul.d $f2, $f12
mul.d $f4, $f2, $f2
li.d $f10, 4.3488777770761457e-04
li.d $f16, 2.2321399879194482e-03
mul.d $f6, $f4, $f10
add.d $f6, $f16
li.d $f10, 1.2500000003771751e-02
mul.d $f6, $f4
add.d $f6, $f10
li.d $f16, 8.3333333333331788e-02
mul.d $f6, $f4
add.d $f6, $f16
mul.d $f6, $f4
mul.d $f6, $f2
cvt.s.d $f0, $f2
cvt.d.s $f0
sub.d $f14, $f0
add.d $f14, $f14
mul.d $f18, $f0
sub.d $f14, $f18
mul.d $f8, $f0
sub.d $f14, $f8
mul.d $f14, $f12
add.d $f14, $f6
add.d $f0, $f14
j ret
7: /* log(+Infinity) = +Infinity */
/* log(NaN) = NaN */
mov.d $f0, $f12
j ret
8: /* x <= 0 or x = NaN */
/* is it zero? ($f10 == 0.0) */
c.eq.d $f12, $f10
bc1f 9f
li.d $f0, -1.0 // generate -INF
li.d $f10, 0.0
div.d $f0, $f10
li t6, FP_Z
j set_log_err
9: /* x < 0.0 or x == NaN */
c.eq.d $f12, $f12
bc1f 7b
li.d $f0, 0.0
div.d $f0, $f10 // generate a NaN
li t6, FP_I
set_log_err:
move $4, t6 // exception mask
move $5, t7 // operation code (funtion name index)
mfc1.d $6, $f12 // arg1
s.d $f0, 16(sp) // default result
xor t5, t5, 0xf80 // inverse exception enable bits
sw t5, 24(sp)
jal _except1
lw ra, FSIZE-4(sp)
addu sp, FSIZE
j ra
ret:
li t6, OP_LOG10
bne t7,t6,retf
li.d $f2, loge
mul.d $f0, $f2
retf:
ctc1 t5, $31 /* restore FCSR */
lw ra, FSIZE-4(sp)
addu sp, FSIZE
j ra
.end log