HP HP-16C - Loop Control with Counters

90 Section 9: Program Branching and Controls
Loop Control with Counters: and
The (decrement and skip next line if counter equals zero) and
(increment and skip if zero) functions can control loop
execution by referencing and adjusting (incrementing/decre-
menting) a counter value in the Index register. Then, when that
counter value reaches zero, program execution skips one line.
Each time one of these functions is encountered in a running
program, the given counter value in the Index register is either
decremented ([DSZ]) or incremented ([1SZ]) by one. If the resulting
value equals zero, the next instruction is skipped. This allows exit
from a loop if the skipped line was a branch into a loop.
Conditional Branch with or
False (R; # 0) True (R} =0)
> EBUA
| \
instruction
(9052 o
|
|
continue loop
L_.y A
exit loop
instruction l__J
“Skip if True”
The value in R} is interpreted according to the current complement
mode. It can be positive or negative, in integer or floating-point
format. The instructions and do not affect the status of
the carry and out-of-range flags.
Example
A “checksum” routine can be used to test the integrity of stored
data values. Using you can determine the sum of a bit pattern
and then compare that sum to the sum of the same bit pattern at a
later time.