User's Manual

iAPX286 MACRO ASSEMBLER
LOC OBJ
0007 98
aooa 8S46FA
0000 2DCl
0000 7722
OODF DF46FC
00E2 SaFe!
00E4 BOEAFE
aOE7 DB6EFO
OOEA D9FD
aOEe 0001
OOEe D9FC
OOFO 0809
OOFe! 9BDD7EFE
00F6 F146FE0040
00F9 7550
OOFO 0008
DOFF BnOb
0101
0101 8907
0103 F708
0105 EBOOOO
0108 OD6EFO
010/3 DEC9
0100 813FI
0101=' 01E6
0111 01E6
011:3 0lE6
0115 OF46FC
0118 DEC2
OIIA D9FD
011C 0009
011E
011E 2EDC940eoo
0123 9BDFEO
0126 A90041
0129 750C
0129 2EOE360000
0130 BaE2FD
01:33 FF07
0135 E814
0137
0137 2EOC940000
013C 9DDFEO
013F A90001
0142 7401
0144 :2EOEOeOOOO
0149 FFOF
0149
0149 D9FC
0140
0140 OF76FO
0150 13E0800
NUMERIC PROGRAMMING EXAMPLES
80287 Floating-Point to is-Digit ASCII Conversion
10: 12: 38 0'1'/25/83 PAGE
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SOURCE
,
i'Li/ait
mov ,ax,poLlla,,_ten
sub ax, ex
J,a adJust_"luult
Wait for power_ten to be valid
I Get powe" of tan of value
I Form scaling factor nacaIl5.,,1,1 in ax
Jump if number will not fit
The number is betwaen 1 ,and 10**<field_lIirel.
Test if it is an intega".
HId
pOLlIa" _
two
mov II i. d x
.ub dl. NORMAL-EXACT
fl'
fraction
fscal a
'"
,t (1)
f"ndint
fcomp
fstsw status
test
status.4000H
J"'
c onvl!rt_i ntagar
htp st(Ol
d x. IIi
I Ra .. to"e original number
S.va "eturn valua
I Conv."t to exact ".tu"n v .. lue
I Form full value. this 1s safe here
Copy value fo" comparl!
J Tast if its an intege"
I Compa"a values
J Save status
C3
a
1 implil!S it was an integl!"
J Remove non integer value
I Restore original return value
Sc,ala the number to Ll/ithin the range allowed by the BCD form,at.
The scaling operation 5hould produce ,a numb.r within one decimal order
of magnitUde of the largut decim.!ll number repra .. ntabla within the
given string width.
nl! seal ing power of ten value is in u.
adJu .. t_ruult:
moy
no,
call
fl'
fmul
moY
'h 1
'h 1
.h 1
Hid
faddp
flcale
htp
word ptr Cbx~ •• u
Practlen
sit ex
si.1
\ii.t
si. 1
power _two
st(2). lit
I s.t initial powe" of ten return value
j Subtract one 'or each order 0'
J magnitude the vo!!Ilue i!li scaled by
Scaling flactor is returned as uponent
and fraction
Q"t .p"action
Combine fractions
I Form pOlller of ten of! the maximum
j BCD value to fit in the string
) Indu in s1
j Combine powlfrs of two
Form full value. exponent wall saile
J Remove exponent
Tl!st the adJu.t.d value against a tablli! of t'~act powers of tt!n.
Til. combined er"or' of thE!' magnitude IIstimatl! and power function ca.,
ret.ult in a value one ordl'r of! magnitude too small 01" too large to fit
corrl!ctly in ,the BCD Held. To handle thi!l pT'obhm. pretest the
adJUsted valull> if it is too small 01' large. than adJust it by ten and
adJust th. powe" of ten value
,
testJower:
f!com power_tableCsiJ+type power_table) Compare against exact power
fstsw
test
J"'
f:Ldiv
an'
in'
Jmp
.,
ax. 4100H
test_fo" _sm,all
const10
d 1. not EXACT
word ptr tb xJ
.ho"t; in_ranga
pOWIi!1"_hbhCsiJ
..
1U.IOOH
1n_range
Umul constiO
dac LIIo"d pt,. Cbx~
flrndint
"
J entry. U!ie thf! ne~t entry since cx
J has been decremented by one
) No lIIait is necessart,!
) If C3 - CO .. 0 than too big
Elu adJust value
Rli!mova axact fllag
I AdJust power of tan value
J Convart the value to a BCD int.g.r
j Test relative size
No wait is naca.sart,!
If! CO - 0 than st(O) >- low.,. bound
I Conv.rt tha valua to a BCD intager
AdJust valu. into range
AdJu.t powar of t.n valua
A .... rt: 0 <- TOS <- 999.999.999.999.999.999
J The TOS number will ba ... c:tll,l repraunhble in 19 digit BCD format.
,
convart_i nteg.,.:
Whih the .to,..e BCD "uns ... etup ragi.tns for the conversion to
ASCII.
I Initial BCD index valua
Figure 4-6. Floating-Point to ASCII Conversion Routine (Cont'd.)
4-11