|Transfer X Index to Accumulator
TXA (Transfer X Index to Accumulator) transfers the value in the X index to the accumulator. The reverse of this opcode is TAX.
This pseudo C code shows how the TXA opcode functions when it is executed.
unsigned src = X; // Load the value of the X index as an unsigned byte.
SET_NEGATIVE(src); // Sets the Negative Flag equal to the 7th bit.
SET_ZERO(src); // Sets the Zero Flag if the Operand is $#00, otherwise clears it.
A = (src); // Stores the value of the X index into the accumulator.