User's Manual

NUMERIC PROGRAMMING EXAMPLES
iAPX286 MACRO ASSEMBLER
80287 rrignometric Functions 10: 13: 51 09/25/83 PAGE
lOC ODJ
00E9 E83300
OOEe EDEO
OOEE
OOEE C3
COEF
DOEF D9E4
OOF! 91
OOF2 '9BDFEO
OOF5 91
OOF6 DDD9
OOFS F6C'40
OOFS 7515
caFD
OOFD D9F2
DOFF
OOFF BAC?
0101 254002
0104 F6C742
0107 7BOD
0109 OAC4
0108 7A02
0100 D9EO
OIOF
OIOF DEF9
0111 C3
0112
0112 D9EB
0114 EBE9
0116
0116 OAC4
011B 7A02
011A D9EO
oue
OllC DEF1
ailE C3
a11F
011F D9El
0121 D9F4
0123 D9EB
0125 DeCl
0127 DEE9
0129 D9FD
0128 DDD9
0120 2EDB2£0000
0132 09C9
0134 C3
ASSEMBLY COMPLETE.
LINE
39.
3.7
3.8
3 ••
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40S
40.
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"B
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.21
.22
• 23
42'
.OS
42.
.27
42B
42.
430
.31
432
'33
43'
.35
43.
.37
.3B
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44B
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4.0
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4.6
467
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.73
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476-
477
47B
.7.
.BO
4Bl
482
4B3
4B4
4B5
NO W"'RNINQS.
SOURCE
call normalize_valu.
Jmp tan_normal
rot
Angle fell in octants 0.2.4.6. Test for 5t(O) - 0, flpti!ln won't work.
flht
xchg
fstsw
xchg
htp
test
J"'
fptan
.u:.cx
.,
ex, Cl
ste 1)
ch, high(mask cond3)
tan_zero
Test for zero engle
I C3 = 1 H st(O) .. 0
I Removtt
PI/4
J ttm sno) .. ST(!)/ST(O)
aft.r _tangent:
Decide on the o"der of the op.rands and their sign for the divide
operation while the fptan instruction is working .
mov
d. btl I Qet a cop", of 'prem C3 P1oI9
and a •• mask cond1 + high(mask cond3), Elamine fprem C3 flag and
j FXAH CI flag
test bh. high(mask condl + mask cond3)l Use rttverse divide if in
, octants 1.2, S. D
Jpo reverse_divid.. Nate! parit", wo"ks low
B bits onllJ!
Angle was in octant. 0.3.4.7.
Test fo" the sign of the r.sult. Tlilo negatives cancel.
or al,ah
Jpe positive_divide
IIdiv
rot
J Form r.sult
I Ok to leave fdiv running
IIdl J Force 1/0 - tanCP1I2)
Jmp aftttr _tangent
Angle lIIas in octant. 1.2.5.0.
Set the correct sign of the result.
,
reverse_divide:
or ai, ah
Jpe positive_r_divide
fdivr
ret
tangent endp
J Form reciprocal oil result
Ok to leave fdiv running
This function 111111 normalize the vilh.l. in steOL
The" PII4 i. placed into .telL
,
normal i ze_value:
fabs
fxtract
fldl
f.dd ste!), st
flub
fscale
flstp stCI)
fld pi_lI.uart."
fxch
ret
code end.
.n.
NO ERRORS
I Force value positive
o <- steO) < I
I get normalize bit
I Normali Ztt fraction
Restor. original value
I Form ori91nal normali zed value
I Remove scala .pactor
Get PII4
Figure 4-7. Calculating Trigonometric Functions (Cont'd.)
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