Floating-Point Unit
MOTOROLA
M68060 USER’S MANUAL
6-27
6.6.3.1 TRAP DISABLED RESULTS (FPCR OPERR BIT CLEARED). For
an
FMOVE
OUT instruction with the format S, D, or X, an OPERR is impossible. For an FMOVE OUT
instruction with the format B, W, or L, an OPERR is possible only on an integer overflow, if
the source is an infinity, or if the source is a NAN. On the integer overflow and infinity source
cases, the largest positive or negative integer that can fit in the specified destination size (B,
W, or L) is stored. On the NAN source case, the 8, 16, or 32 most significant bits of the NAN
significand is stored in the B, W, or L destination.
For FMOVE OUT with the format P (packed decimal), if the k-factor is greater than +17, the
result returned is a packed decimal string that assumes a k-factor equal to +17. For packed
decimal results where the absolute value of the exponent is greater than 999, the decimal
string is returned with the three least significant exponent digits in EXP2, EXP1, and EXP0.
The fourth digit, EXP3, is supplied in the most significant four bits of the third byte in the
string.
For all other OPERR cases, the destination is a floating-point data register. An extended-
precision non-signaling NAN is stored in the destination.
6.6.3.2 TRAP ENABLED RESULTS (FPCR OPERR BIT SET). For
the
FMOVE
OUT
cases, the destination is written as if the trap were disabled, and then control is passed to
Table 6-12. Possible Operand Errors Exceptions
Instruction
Condition Causing Operand Error
Native to MC68060
FADD
[(+
∞) + (–∞)] or [(–∞) + (+∞)]
FDIV
(0
÷ 0) or (∞ ÷ ∞)
FMOVE to B,W,or L
Integer overflow, source is nonsignaling NAN or
±∞
FMUL
One operand is 0 and other is +
∞
FSQRT
(Source < 0) or (
∞)
FSUB
[(+
∞) – (+∞)] or [(–∞) – (–∞)]
Non-Native to MC68060
FACOS
Source is
±∞, > +1, or < –1
FASIN
Source is
±∞, > +1, or < –1
FATANH
Source is
±∞, > +1, or < –1
FCOS
Source is
±∞
FGETEXP
Source is
±∞
FGETMAN
Source is
±∞
FLOG10
Source is < 0 or
∞
FLOG2
Source is < 0 or
∞
FLOGN
Source is < 0 or
∞
FLOGNP1
Source is
≤ 1 or ∞
FMOD
Floating-point data register is
±∞ or source is 0, other operand is not a NAN
FMOVE to P
Source exponent > 999 (decimal) or k-factor > 17
FREM
Floating-point data register is
±∞ or source is 0, other operand is not a NAN
FSCALE
Source is
±∞, other operand not a NAN
FSGLDIV
(0
÷ 0) or(∞ ÷ ∞)
FSGLMUL
One operand is 0, other operand is
∞
FSIN
Source is
±∞
FSINCOS
Source is
±∞
FTAN
Source is
±∞