AMD-K6 AMD [Advanced Micro Devices], AMD-K6 Datasheet - Page 45

• Manufacturer Part Number: AMD-K6
• Description: AMD-K6 Processor
• Manufacturer: AMD [Advanced Micro Devices]

20695H/0—March 1998
Figure 12. FPU Control Word Register
Figure 13. FPU Tag Word Register
Chapter 3
Symbol
Y
RC
PC
PM
UM
OM
ZM
DM
IM
00b = Round to the nearest or even number
01b = Round down toward negative infinity
10b = Round up toward positive infinity
11b = Truncate toward zero
Rounding Control Information
Reserved
Infinity Bit (80287 compatibility) 12
Rounding Control
Precision Control
Precision
Underflow
Overflow
Zero Divide
Denormalized Operation
Invalid Operation
Description
Exception Masks
The FPU control word register allows a programmer to manage
the FPU processing options. Figure 12 shows the format of this
register.
The FPU tag word register contains information about the
registers in the register stack. Figure 13 shows the format of this
register.
15
(FPR7
TAG
14
13
(FPR6
TAG
12
11
(FPR5
Software Environment
TAG
Bits
11–10
9–8
2
0
5
4
3
1
10
Tag Values
00 = Valid
01 = Zero
10 = Special
11 = Empty
(FPR4
9 8
TAG
15
14
(FPR3
7
TAG
13
00b = 24 bits Single Precision Real
01b = Reserved
10b = 53 bits Double Precision Real
11b = 64 bits Extended Precision Real
6
Precision Control Information
12
Y
(FPR2
5
TAG
11
4
C
R
10
(FPR1
3
TAG
9 8
2
P
C
(FPR0
1
TAG
7
0
AMD-K6
6
M
5
P
M
U
4
®
M
O
Processor Data Sheet
3
M
Z
2
D
M
1
M
0
I
27