AMD Am186 Series, Instruction Set

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Instruction Set 4-89
JE Jump If Equal JE
JZ Jump If Zero
What It Does
If the previous instruction sets the Zero Flag (ZF), JE and JZ stop executing the current
sequence of instructions and begin executing a new sequence of instructions; otherwise,
execution continues with the next instruction.
Syntax
Description
JE and JZ test the flag set by a previous instruction. If the given condition is true (ZF=1),
a short jump is made to the location provided as the operand.
Operation It Performs
Flag Settings After Instruction
Form Opcode Description
Clocks
Am186 Am188
JE
rel8
74
cb
Jump short if equal (ZF=1) 13,4 13,4
JZ rel8 74 cb Jump short if 0 (ZF=1) 13,4 13,4
JE label
To jump if the result of a previous integer
or unsigned comparison was equal, use
JE or its synonym, JZ. Both forms
perform the same function.
JZ label
if (ZF == 1)
{
/* extend sign of label */
if ( label < 0)
displacement = 0xFF00 |
label;
else
displacement = 0x00FF &
label;
/* branch to labeled instruction */
IP = IP + displacement;
}
15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
Processor Status
Flags Register
reserved
OF DF IF TF SF ZF AF PF CF
? = undefined; – = unchanged
– – – – – – res – res – res –