EC000 Core Processor
MOTOROLA
MC68307 USER’S MANUAL
4-5
If <condition>
then <operations>
else <operations>
Test the condition. If true, the operations after “then” are performed. If the condition is false and
the optional “else” clause is present, the operations after “else” are performed. If the condition is
false and else is omitted, the instruction performs no operation. Refer to the Bcc instruction de-
scription as an example.
Register Specification
An
Any Address Register n (example: A3 is address register 3)
Ax, Ay
Source and destination address registers, respectively.
BR
Base Register—An, PC, or suppressed.
Dc
Data register D7–D0, used during compare.
Dh, Dl
Data registers high- or low-order 32 bits of product.
Dn
Any Data Register n (example: D5 is data register 5)
Dr, Dq
Data register’s remainder or quotient of divide.
Du
Data register D7–D0, used during update.
Dx, Dy
Source and destination data registers, respectively.
Rn
Any Address or Data Register
Rx, Ry
Any source and destination registers, respectively.
Xn
Index Register—An, Dn, or suppressed.
Data Format And Type
<fmt>
Operand Data Format: Byte (B), Word (W), Long (L), or Packed (P).
B, W, L
Specifies a signed integer data type (twos complement) of byte, word, or long word.
k
A twos complement signed integer (–64 to +17) specifying a number’s format to be stored in the
packed decimal format.
Subfields and Qualifiers
#<xxx> or #<data>
Immediate data following the instruction word(s).
( )
Identifies an indirect address in a register.
[ ]
Identifies an indirect address in memory.
bd
Base Displacement
dn
Displacement Value, n Bits Wide (example: d16 is a 16-bit displacement).
LSB
Least Significant Bit
LSW
Least Significant Word
MSB
Most Significant Bit
MSW
Most Significant Word
od
Outer Displacement
SCALE
A scale factor (1, 2, 4, or 8, for no-word, word, long-word, or quad-word scaling, respectively).
SIZE
The index register’s size (W for word, L for long word).
{offset:width}
Bit field selection.
Register Names
CCR
Condition Code Register (lower byte of status register)
PC
Program Counter
SR
Status Register
Register Codes
*
General Case.
C
Carry Bit in CCR
cc
Condition Codes from CCR
FC
Function Code
N
Negative Bit in CCR
U
Undefined, Reserved for Motorola Use.
V
Overflow Bit in CCR
X
Extend Bit in CCR
Z
Zero Bit in CCR
—
Not Affected or Applicable.
Table 4-3. Notation Conventions (Continued)