Freescale Semiconductor MC68881 - Page 122

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FMOVE .ov Floating-Point Data Register FMOVE
Operation: Source $ Destination
Assembler FMOVE.<fmt> <ea>,FPn
Syntax: FMOVE.<fmt> FPm,<ea>
FMOVE.P FPm,<ea>{Dn}
FMOVE.P FPm,<ea>{#k}
Attributes: Format = (Byte, Word, Long, Single, Double, Extended, Packed)
Description: Moves the contents of the source operand to the destination operand.
Although the primary function of this instruction is data movement, it is also consid-
ered an arithmetic instruction since conversions from the source operand format to
the destination operand format are performed implicitly during the move operation.
Also, the source operand is rounded according to the selected rounding precision and
mode.
Unlike the M68000 Family integer data movement instruction, the floating-point move
instruction does not support a memory-to-memory format (for such transfers, it is
much faster to utilize the M68000 Family integer MOVE instruction to transfer the
floating-point data than to use the FMOVE instruction). The FMOVE instruction only
supports memory-to-register, register-to-register, and register-to-memory operations
(in this context, memory may refer to an MPU data register if the data format is byte,
word, long or single). The memory-to-register and register-to-register operations use
a command word encoding distinctly different from that used by the register-to-memory
operation, and these two operation classes are described separately below.
Memory-to-Register or Register-to-Register Operation:
Converts the source operand to an extended precision floating-point number (if nec-
essary) and stores it in the destination floating-point data register. Depending on the
source data format and the rounding precision, some operations may produce an
inexact result. In the following table, combinations that can produce an inexact result
are marked with a dot (e), but all other combinations produce an exact result.
Source Format: B W L S D X P
Rounding Precision: Single • • • •
Double • •
Extended •
Status Register:
Condition Codes: Affected as described in 4.5.5.1 SETTING FLOATING-POINT
CONDITION
CODES
Quotient Byte: Not affected
FREESCALE
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