Syntax: TST {<cond>} {<P>} <operand1>, <operand2>
Operation: Reflect result of operand one AND operand two
Flags: N,Z,(C)
This instruction performs the logical bitwise ANDing of operands one and two, but does not store the result anywhere - instead the status flags are altered to reflect the result.
TST can be used to see if a particular bit in a data word is set or clear. The data word forms one operand. A bit mask, in which the appropriate bit is et, forms the other operand. After the TST operation the Z flag will be set if the bit is set in the data word, clear if it is not.
Examples:
TST R1,#%1000 ; Test to see if bit 3 is set in R1
TST R3,R4 ; Test if any bits set in both R3 and R4
Like CMP and CMN,this is another instruction where the S suffix is implied.
The C flag is set to the carry output bit generated by the shifter.
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