Logical Operations
Test and Change Memory Instructions
The compare (CMPx) and test (Txxx) instructions allow the ability to test values in memory. The
results of these operations can then trigger subsequent conditional branches. The CMPx instruc-
tion allows comparison of memory with respect to a specified constant value, while the Txxx in-
structions allow any single bit to be extracted to the test control (TC) field of status register 0.
The contents of the accumulator can also be non-destructively analyzed to establish branching
conditions, as seen below.
Test and Change Memory
Instruction Execution Affects
TBIT loc16,#(0-15)
ST0(TC) = loc16(bit_no) TC
TSET loc16,#(0-15) Test (loc16(bit)) then set bit TC
TCLR loc16,#(0-15) Test (loc16(bit)) then clr bit TC
CMPB AX, #8bit Test (AX - 8bit unsigned) C,N,Z
CMP AX, loc16 Test (AX – loc16) C,N,Z
CMP loc16,#16b Test (loc16 - #16bit signed) C,N,Z
CMPL ACC, @P Test (ACC - P << PM) C,N,Z
C - 16 C28x - Appendix C - Assembly Programming
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