Motorola M68000 User Manual download pdf (Page 57)

Floating Point Instructions

5-46 M68000 FAMILY PROGRAMMER’S REFERENCE MANUAL MOTOROLA

FGETEXP Get Exponent FGETEXP

(MC6888X, M68040FPSP)

Operation: Exponent of Source → FPn

Assembler FGETEXP. < fmt > < ea > ,FPn

Syntax: FGETEXP.X FPm,FPn

FGETEXP.X FPn

Attributes: Format = (Byte, Word, Long, Single, Double, Extended, Packed)

Description: Converts the source operand to extended precision (if necessary) and

extracts the binary exponent. Removes the exponent bias, converts the exponent to an

extended-precision ﬂoating- point number, and stores the result in the destination

ﬂoating- point data register.

Operation Table:

NOTES:

1. If the source operand is a NAN, refer to 1.6.5 Not-A-Numbers for more information.

2. Sets the OPERR bit in the ﬂoating-point status register exception byte.

Floating-Point Status Register:

Condition Codes: Affected as described in 3.6.2 Conditional Testing.

Quotient Byte: Not affected.

Exception Byte: BSUN Cleared

SNAN Refer to 1.6.5 Not-A-Numbers.

OPERR Set if the source is ± infinity; cleared

otherwise.

OVFL Cleared

UNFL Cleared

DZ Cleared

INEX2 Cleared

INEX1 If < fmt > is packed, refer to inexact result on

decimal input in the appropriate user’s

manual; cleared otherwise.

Accrued Exception Byte: Affected as described in IEEE exception and trap compati-

bility in the appropriate user’s manual.

DESTINATION

SOURCE

+ In Range – + Zero – + Inﬁnity –

Result Exponent

+ 0.0 – 0.0

NAN

1 2 ... 52 53 54 55 56 57 58 59 60 61 62 ... 356 357

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Motorola M68000 User Manual Page 57