Motorola CPU32 Reference Manual page 123

II
DBee
Test Condition, Decrement, and Branch
Instruction Format:
15 14 13 12 11 10 9 8
CONDITION
DISPLACEMENT
Instruction Fields:
Condition field - The binary code for one of the conditions listed in the table.
Register field - Specifies the data register used as the counter.
Displacement field - Specifies the number of bytes to branch.
NOTES:
DBee
2 0
REGISTER
1. Terminating condition is similar to UNTIL loop clauses of high-level languages. For
example, DSMI can be stated "decrement and branch until minus."
2. Most assemblers accept DSRA for DSF when a count terminates the loop (no condition is
tested).
3. A program can enter a loop at the beginning, or by branching to the trailing DScc
instruction. Entering the loop at the beginning is useful for indexed addressing modes
and dynamically specified bit operations. In this case, the control index count must be one
less than the desired number of loop executions. However, when entering a loop by
branching to the trailing DScc instruction, the control count should equal the loop
execution countso that the DScc instruction will not branch and the main loop will not
executeif a zero count occurs.
MOTOROLA
4-70
INSTRUCTION SET
CPU32 REFERENCE MANUAL