Echelon Neuron - Manual (Page 83)

BRNC (Branch If Not Carry)
The BRNC instruction performs a conditional branch if the Carry flag is not set.
The BRNC instruction uses the relative addressing mode. The BRNC
instruction branches forward or backward with a signed relative displacement of
-126 to +129 bytes if the Carry flag is not set; otherwise, program operation
continues with the next instruction. The displacement expression must resolve at
link time to a value in the range -128 to +127 (two less than the actual
displacement because the displacement calculation includes the size of the
BRNC operation itself).
The Neuron Assembler also supports the use of a label for the displacement
expression; manual calculation of the displacement value is not required.
See also BRC (Branch If Carry).
The BRNC instruction applies to Series 3100, 5000, and 6000 devices.
Syntax:
The BRNC instruction requires a single operand to specify the displacement or
label:
BRNC displacement
BRNC label
Table 19 describes the attributes of the BRNC instruction.
Table 19. BRNC Instruction
Instruction Hexadecimal
Opcode
Instruction
Size (Bytes)
CPU Cycles
Required
Affect on
Carry Flag
BRNC 32 2 2 Used
Example:
The following example assumes that TOS and NEXT have data values to be
added. The ADD instruction adds them and sets the Carry flag for the unsigned
addition. The BRNC instruction branches to the Ok label if the Carry flag is not
set, otherwise the program continues. The BR instruction ensures that the code
at the Ok label is only run when needed.
add ; (result, -, -)
brnc Ok
... ; handle Carry set condition
br Common
Ok ...
Common ...
Neuron Assembly Language Reference 73