Zilog Z8F0130 - Manual (Page 117)

eZ8
™
CPU Core
User Manual
UM012820-0810 BTJ Instruction
102
BTJ
Definition
Bit Test and Jump.
Syntax
BTJ p, bit, src, DA
Operation
if src[bit] = p {

PC
 PC + X
}
In the operation above, the jump offset, X , is calculated by the eZ8 CPU
assembler from Program Counter value, PC , and the Destination Address,
DA .
Description
For this new eZ8 instruction, the selected bit in the source operand or reg-
ister pointed to by the source operand is compared with the
p flag. If the
bit in the source is equal to the polarity p , the signed displacement, X , is
added to the Program Counter, which causes a jump. The displacement
value can be from –128 to +127. This instruction tests only a single bit
position. Multiple bits cannot be tested simultaneously.
Table 21. BTJ Operand Description
Polarity Bit (p)
Bit Position Tested Operand[3:0]
Decimal Binary Binary Hexadecimal
0 0 000 0000 0
0 1 001 0001 1
0 2 010 0010 2
0 3 011 0011 3