Table 8-16. Output Operand Conversion
Dest.
Format ~ Source
J Type
Normalized Not
+
-
Normalized
Zero Infinity
NAN
Integer, No Overflow 50 52 60 62 18 -- 24
Integer, Overflow 52 56 62 66 18 24 26 24
Single (see below) (see below) 16 18 NAN7
Double (see below) (see below) 16 18 NAN7
Extended 18 (see note 1) 16 16 NAN7
Packed (see note 2) (see note 2) 24 24 NAN2
NOTES:
1. 26 clocks if the source operand is an unnormalized number. 56 clocks if the source operand is a
denormelized number.
2. 1942 clocks is the typical time required for the conversion, if no overflow occurs. The maximum
time is 3674 clocks.
Table 8-17. Output Operand Conversion -- Binary Real Formats
pe Normalized Not Normalized
No Underflow, Overflow or Round Overflow 38 48
No Underflow or Overflow; Round Overflow 42 52
Overflow; RN or RZ Mode; No Round Overflow 44 54
Overflow; RN or RZ Mode; Round Overflow 48 58
Overflow; RM or RP Mode; No Round Overflow 46 56
Overflow; RM or RP Mode; Round Overflow 50 60
Underflow; No Round Overflow 66 76
Underflow; Round Overflow 70 80
Table 8-18. Rounding Operation Time Values
Rounding Result Clock Cycles
Precision
Extended
Single or
Double
No Underflow, Overflow, or Round Overflow
No Underflow or Overflow; Round Overflow
Underflow
Overflow; RN or RZ Mode; No Round Overflow
Overflow; RM or RP Mode; No Round Overflow
Round Overflow (Not Caused By Rounding); RN or RZ Mode
Round Overflow (Not Caused By Rounding); RM or RP Mode
Round Overflow (Caused By Rounding); RN or RZ Mode
Round Overflow (Caused By Rounding); RM or RP Mode
Result is Zero
No Underflow, Overflow, or Round Overflow
No Underflow or Overflow; Round Overflow
Underflow; No Round Overflow
Underflow; Round Overflow
Overflow; RN or RZ Mode; No Round Overflow
Overflow; RM or RP Mode; No Round Overflow
Overflow; RN or RZ Mode; Round Overflow
Overflow; RM or RP Mode; Round Overflow
6
6
34
14
16
16
18
20
22
6
24
28
56
60
30
32
34
36
MC68881/MC68882 USER'S MANUAL FREESCALE
8-35
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