Propeller Manual

3: Assembly Language Reference – NR
NR
Effect: Prevent assembly instruction from writing a result.
〈Label〉 〈Condition〉 Instruction Operands NR
Result: Instruction’s destination register is left unaffected.
• Label is an optional statement label. See Common Syntax Elements on page 250.
•
Condition is an optional execution condition. See Common Syntax Elements on page 250.
•
Instruction is the desired assembly instruction.
•
Operands is zero, one, or two operands as required by the Instruction.
Explanation
NR (No Result) is one of four optional effects (WC, WZ, WR, and NR) that influence the behavior
of assembly instructions.
NR causes an executing assembly instruction to leave the destination
register’s value unaffected.
For example, by default the
SHL (Shift Left) instruction shifts the destination value left a
number of bits, writes the result back into the destination register, and optionally indicates
status via the C and Z flags. If all that you really need is the
SHL instruction’s C flag status,
simply specify it with both the
WC and NR effects:
shl value, #1 WC, NR 'Put value's MSB in C
The above example effectively sets the C flag to the state of value’s high bit (bit 31) without
affecting the final contents of
value.
See Effects on page 291 for more information.
Propeller Manual v1.1 · Page 325