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II
BRA
Branch Always
BRA
Operation:
Assembler
Syntax:
Attributes:
PC+d~
PC
BRA (label)
Size
=
(Byte, Word, Long)
Description:
Program execution continues at location (PC) + displacement. The PC contains the
address of the instruction word of the BRA instruction plus two. The displacement is a twos
complement integer that represents the relative distance in bytes from the current PC to the
destination PC. If the 8-bit displacement field in the instruction word is zero, a 16-bit displacement
(the word immediately following the instruction) is used. If the 8-bit displacement field in the
instruction word is all ones ($FF), the 32-bit displacement (long word immediately following the
instruction) is used.
Condition Codes:
Not affected.
Instruction Format:
15
14
13
12
11
10
9
8
7
6
5
4
3
2
o
o
I
1
I
1
I
o
I
o
I
o
I
o
I
o
I
8-BIT DISPLACEMENT
16-BIT DISPLACEMENT IF 8-BIT DISPLACEMENT
=
$00
32-BIT DISPLACEMENT IF 8-BIT DISPLACEMENT
=
$FF
Instruction Fields:
8-Bit Displacement field -
Twos complement integer specifying the number of bytes between
the branch instruction and the next instruction to be executed.
16-Bit Displacement field - Used for a larger displacement when 8-bit displacement is $00.
32-Bit Displacement field - Used for a larger displacement when 8-bit displacement is $FF.
MOTOROLA
4-48
NOTE
A branch to the instruction imll)ediately following automatically uses 16-bit
displacement because the 8-bit displacement field contains $00 (zero offset).
INSTRUCTION SET
CPU32 REFERENCE MANUAL
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