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BRA
Operation:
Assembler
Syntax:
Attributes:
Description:
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
0
1
1
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.
A branch to the instruction immediately following automatically uses
16-bit displacement because the 8-bit displacement field contains
$00 (zero offset).
CPU32
REFERENCE MANUAL
Branch Always
PC + d → PC
BRA 〈label〉
Size = (Byte, Word, Long)
Program execution continues at location (PC) + displacement. The
12
11
10
9
0
0
0
0
16-BIT DISPLACEMENT IF 8-BIT DISPLACEMENT = $00
32-BIT DISPLACEMENT IF 8-BIT DISPLACEMENT = $FF
INSTRUCTION SET
8
7
6
5
0
8-BIT DISPLACEMENT
NOTE
BRA
4
3
2
1
MOTOROLA
0
4-43
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