4/17/98 6-99 Addressing Modes and Data Types
JBC Jump if bit is set then clear bit
Syntax: JBC bit, rel8
Operation: (PC) <-- (PC) + 4
if (bit) = 1 then
(PC) <-- (PC + rel8*2);
(PC.0) <-- 0; (bit) <-- 0
Description: If the bit specified is set, branch to the address pointed to by the PC plus the specified
displacement. The specified bit is then cleared allowing implementation of semaphore operations.
If the specified bit is clear, the instruction following JBC is executed. The branch range is +254
bytes to -256 bytes, with the limitation that the target address is word aligned in code memory.
Note: Refer to section 6.3 for details of jump range
Size: Bit
Flags Updated: none
Bytes:4
Clocks: 11t/7nt
Encoding:
byte 3: lower 8 bits of bit address
byte 4: rel8
1 0 0 1 0 1 1 1
1 1 0 0 0 0 bit: 2
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