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Instruction Classification
4-41Assembly Language Instructions
Table 4–31. Class 7 Instruction Encoding and Description (Continued)
cc
cc names
Description
cc
cc name Not cc name
1 0 1 0 1 Unconditional
1 0 1 1 0 Not assigned
1 0 1 1 1 Not assigned
1 1 0 0 0 XZ XNZ Conditional on XSF
1 1 0 0 1 XS XNS Conditional on XZF
1 1 0 1 0 XG XNG Conditional on ! XSF and ! XZF
1 1 0 1 1 Not assigned
1 1 1 0 0 Not assigned
1 1 1 0 1 Not assigned
1 1 1 1 0 Not assigned
1 1 1 1 1 Not assigned
4.4.8 Class 8 Instructions: Logic and Bit
This class of instructions provides a flexible and efficient means to make
complex logical decisions. Instead of making a sequence of single bit
decisions and constructing a logical statement through a branch decision tree,
the program can sequentially combine several status conditions to directly
construct a final logic value (TF1 or TF2) which can be used to control a
subsequent branch or call. This class includes two subclasses. Class 8a
instructions update one of the test flags (TF1 or TF2) with a logical combination
of the old test flag value and an addressed memory flag value. Subclass 8b
provides a flexible means of logically combining the test flag (TF1 or TF2) with
a status condition and storing the results back to the test flag.
Table 4–32. Class 8a Instruction Encoding
Bit 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
Class 8a 1 0 0 1 1 flg Not C8a flagadrs
Class 8b 1 0 0 1 0 flg Not cc Rx C8b
RFLAG {flagadrs} 1 0 0 1 1 0 0 0 1 1 flagadrs
SFLAG {flagadrs} 1 0 0 1 1 1 0 1 0 1 flagadrs