AMD Am186 Series, Instruction Set

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Instruction Set 4-95
JL Jump If Less JL
JNGE Jump If Not Greater or Equal
What It Does
If the previous instruction modifies the Sign Flag (SF) and the Overflow Flag (OF) so that
they are not the same, JL and JNGE stop executing the current sequence of instructions
and begin executing a new sequence of instructions; otherwise, execution continues with
the next instruction.
Syntax
Description
JL and JNGE test the flags set by a previous instruction. The terms
greater and less indicate
an integer (signed) comparison. If the given condition is true (SF
≠
OF), 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
JL
rel8
7C
cb
Jump short if less (SF
≠
OF) 13,4 13,4
JNGE rel8 7C cb Jump short if not greater or equal (SF
≠
OF) 13,4 13,4
JL
label
To jump if the result of a previous integer
comparison was less, use JL or its
synonym, JNGE. Both forms perform the
same operation.
JNGE label
if (SF != OF)
{
/* 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 –