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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 ±∞
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