O'Reilly logo
  • You Wang thinks this is interesting:

test can be used for the fastest 'is it a zero?' check

Note

The TEST instruction performs a logical AND of two operands and sets the SF, ZF, and PF flags according to the results. The flags can then be tested by the conditional jump or loop instructions or the SETcc instructions. The TEST instruction differs from the AND instruction in that it does not alter either of the operands.