Hitachi NT2021XA, Instruction Manual

Page: 26 / 84

Chapter 2 Syntax
if statement Instruction to branch processing unconditionally
- Format
Format Description
if <condition> then <label name>
When <condition> is met, processing branches to the step labeled with
<label name> .
When <condition> is not met, processing proceeds to the next step (line).
- Explanation
Use this instruction to branch processing conditionally.
When
<condition> is met, processing branches to the step labeled with <label name> described after “then.”
<condition> : Specifies a conditional expression among those listed in Section 2.2, “ List of Instructions (2) Conditional
expressions.”
<label name> : Specifies the label name of the branch-target step (line).
- Processing cycle
Note that <condition> check and branch processing are executed in the same cycle.
Refer to the statement execution sequence indicated by parenthesized numbers in the comment fields of the sample programs
below.
- Sample program
Label Mnemonic parameter1 parameter2 parameter3 parameter4 parameter5
㩷
㩷
Yw= 0
㩷 㩷 㩷 㩷
: Turn off terminals Y (00) to Y (05).
㩷
if X(00) = 1 then LABEL1
: (1) When <condition> is met, branch to
step "LABEL1."
㩷
if X(01) = 1 then LABEL2
: (2) When <condition> is met, branch to
step "LABEL2."
㩷
Y(00)= 1
㩷 㩷 㩷 㩷
: (3)
㩷
goto LABEL3
㩷 㩷 㩷 㩷
: (4) (2)
LABEL1 Y(01)= 1
㩷 㩷 㩷 㩷
: (3)
㩷
goto LABEL3
㩷 㩷 㩷 㩷
:
LABEL2 Y(02)= 1
㩷 㩷 㩷 㩷
: (3)
LABEL3 Y(03)= 1
㩷 㩷 㩷 㩷
: (5) (4) (4)
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