9.14 Check bits during comparison operation

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If BX & 5 is found in the left part of the comparison expression, then

when the expression is calculated, the contents of register BX will be

changed by the instruction 'and'. But sometimes it is necessary to check

the bits without changing the contents of register BX. The instruction

'test' can be used for this purpose. How can we tell the compiler where to

use 'and' and where 'test? In standard C the method of priorities is used -

if the expression is in brackets, calculate it, otherwise test it. But C--

does not support the method of priorities, and so the problem is solved by

direct use of 'test. The following syntax variants are possible:

IF ( $test AX,5 )

IF ( ! $test AX,5)

IF ( asm test AX,5)

IF ( ! asm { test AX,5 } )