Central Processing Unit
MPC561/MPC563 Reference Manual, Rev. 1.2
Freescale Semiconductor
3-15
12
VXVC
Floating-point invalid operation exception for invalid compare.
Sticky bit
13
FR
Floating-point fraction rounded. The last floating-point instruction that
potentially rounded the intermediate result incremented the fraction.
Not sticky
14
FI
Floating-point fraction inexact. The last floating-point instruction that
potentially rounded the intermediate result produced an inexact fraction or a
disabled exponent overflow.
Not sticky
[15:19]
FPRF
Floating-point result flags. This field is based on the value placed into the
target register even if that value is undefined. Refer to
for specific bit
settings.
15 Floating-point result class descriptor (C). Floating-point instructions other
than the compare instructions may set this bit with the FPCC bits, to
indicate the class of the result.
16-19 Floating-point condition code (FPCC). Floating-point compare
instructions always set one of the FPCC bits to one and the other three
FPCC bits to zero. Other floating-point instructions may set the FPCC bits
with the C bit, to indicate the class of the result. Note that in this case the
high-order three bits of the FPCC retain their relational significance
indicating that the value is less than, greater than, or equal to zero.
16 Floating-point less than or negative (FL or <)
17 Floating-point greater than or positive (FG or >)
18 Floating-point equal or zero (FE or =)
19 Floating-point unordered or NaN (FU or ?)
Not sticky
20
—
Reserved
—
21
VXSOFT
Floating-point invalid operation exception for software request. This bit can be
altered only by the mcrfs, mtfsfi, mtfsf, mtfsb0, or mtfsb1 instructions. The
purpose of VXSOFT is to allow software to cause an invalid operation
condition for a condition that is not necessarily associated with the execution
of a floating-point instruction. For example, it might be set by a program that
computes a square root if the source operand is negative.
Sticky bit
22
VXSQRT
Floating-point invalid operation exception for invalid square root. This
guarantees that software can simulate fsqrt and frsqrte, and can provide a
consistent interface to handle exceptions caused by square root operations.
Sticky bit
23
VXCVI
Floating-point invalid operation exception for invalid integer convert.
Sticky bit
24
VE
Floating-point invalid operation exception enable.
—
25
OE
Floating-point overflow exception enable.
—
26
UE
Floating-point underflow exception enable. This bit should not be used to
determine whether denormalization should be performed on floating-point
stores.
—
27
ZE
Floating-point zero divide exception enable.
—
28
XE
Floating-point inexact exception enable.
—
Table 3-5. FPSCR Bit Descriptions (continued)
Bits
Name
Description
Summary of Contents for MPC561
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