
9- 24
M68040 USER’S MANUAL
MOTOROLA
DENORMALIZED SINGLE PRECISION
31 30
23 22
0
39
40
62
63
64
79
80
94
95
$0
S
$0
0
FORMAT IN STATE FRAME
MANTISSA
EXP
S
FRACTION
DENORMALIZED DOUBLE PRECISION
63 62
52 51
0
10
11
62
63
64
79
80
94
95
$0
S
$0
0
FORMAT IN STATE FRAME
MANTISSA
EXP
S
MANTISSA
(a) Single Precision
(b) Double Precision
Figure 9-9. Format of Denormalized Operand in State Frame
9.7 FLOATING-POINT ARITHMETIC EXCEPTIONS
The following eight user floating-point arithmetic exceptions are listed in order of priority.
The MC68040 generates the first seven exceptions in hardware and the eighth only in
software.
Branch/Set on Unordered (BSUN)
Signaling Not-A-Number (SNAN)
Operand Error (OPERR)
Overflow (OVFL)
Underflow (UNFL)
Divide by Zero (DZ)
Inexact 2 (INEX2)
Inexact 1 (INEX1)
INEX1 exception is the condition that exists when a packed decimal operand cannot be
converted exactly to the extended-precision format in the current rounding mode. Since