AMD-K6 Datasheet, PDF (44/346 Pages) Advanced Micro Devices – AMD-K6 Processor

AMD-K6^® Processor Data Sheet
Preliminary Information
20695H/0—March 1998
79 78
Sign
The eight floating-point registers are 80 bits wide and labeled
FPR0–FPR7. Figure 10 shows the format of these floating-point
registers. See “Floating-Point Register Data Types” on page 28
for information on allowable floating-point data types.
Exponent
64 63
0
Significand
Figure 10. Floating-Point Register
The 16-bit FPU status word register contains information about
the state of the floating-point unit. Figure 11 shows the format
of this register.
15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
BC
3
TOSP
CCC E S PUOZ D I
210SF EEEE EE
Symbol
B
C3
TOSP
C2
C1
C0
ES
SF
PE
UE
OE
ZE
DE
IE
Description
Bits
FPU Busy
15
Condition Code
14
Top of Stack Pointer
13–11
Condition Code
10
Condition Code
9
Condition Code
8
Error Summary Status
7
Stack Fault
6
Exception Flags
Precision Error
5
Underflow Error
4
Overflow Error
3
Zero Divide Error
2
Denormalized Operation Error 1
Invalid Operation Error
0
TOSP Information
000 = FPR0
111 = FPR7
Figure 11. FPU Status Word Register
26
Software Environment
Chapter 3