Zilog Z8F0130 Manual de usuario Pagina 117

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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
0301100113
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