HP HP-16C - Page 49

Section 4: Arithmetic and Bit Manipulation Functions 47
Left-Justify. To left-justify a bit pattern within its word size,
press (9] [LJ]. The stack will lift, placing the left-justified word in
the Y-register and the count (number of bit-shifts necessary to left-
justify the word) in the X-register. The carry flag is not affected by
[LJ).
Example: Left-justify the binary value 1111 in a word size of
eight.
Keystrokes Display ([STATUS]: 2-08-0000)
1111 1111 b
(9] 100 b The count: four bit-shifts
to left-justify the word.
11110000 b Left-justified word.
Arithmetic Shift Right. Pressing (9] (arithmetic shift
right) will move the contents of the word in the X-register one bit to
the right, as does [SR]. However, instead of placing a zero into the
new place at the left of the word, the sign bit is regenerated. (In
Unsigned mode, which has no sign bit, operates like [SR].)
The carry bit is set if a 1 is shifted out of the X-register and cleared
if 0 1s shifted out.
ASR [ « > | > D
C
Sign Bit Unchanged
Example: Shifting a positive binary number to the right n places
is equivalent to dividing it by 2”. Since it regenerates the sign bit,
an arithmetic shift also can be used to divide an even negative
integer by 2.* Divide 01111111 (word size 8) by 2%, then divide
10000000 by 23,
Keystrokes Display ([STATUS]: 2-08-0000)
(9]
3
Allows
display
of
leading zeros.
1111111 01111111 b
*For odd negative integers in 2’s Complement mode, gives a result one less than
division by 2.