Effect: Cause assembly instruction to modify the C flag.

<Label > <Condition > Instruction Operands WC

Result: C flag is updated with status from the Instruction's execution.

• Label is an optional statement label. See Common Syntax Elements.
• Condition is an optional execution condition. See Common Syntax Elements.
• Instruction is the desired assembly instruction.
• Operands is zero, one, or two operands as required by the Instruction.

Explanation

WC (Write C flag) is one of four optional effects (NR, WR, WZ, and WC) that influence the behavior of assembly instructions. WC causes an executing assembly instruction to modify the C flag in accordance with its results.

For example, the CMP (Compare Unsigned) instruction compares two values (destination and source) but does not automatically write the results to the C and Z flags. You can determine if the destination value is less than the source value by using the CMP instruction with the WC effect:

cmp    value1, value2    WC    'C = 1 if value1 < value2 

The above CMP instruction compares value1 with value2 and sets C high (1) if value1 is less than value2.

See Effects (WC, WZ, WR, NR) for more information.