Motorola CPU32 Reference Manual page 253

III
x x
y
(Subroutine) (Instruction)
0 0 0
1 256 16
2 512 32
3
768 48
4
1024 64
5
1280
80
6 1536 96
7 1792 112
8 2048 128
9 2304 112
10 2560 96
11 2816 80
12 3072 64
13 3328 48
14 3584 32
15 3840 16
16 4096 0
The first column is the value passed to the subroutine, the second column is the
value expected by the table instruction, and the third column is the result
returned by the subroutine.
The following value has been calculated for independent variable X:
31
16 15 0
NOT USED
0 0 0 0 0 0 0 0 1 0 1 1 1 1 0 1
Since X is an 8-bit value, the upper four bits are used as a table offset and the
lower four bits are used as an interpolation fraction. The following results are
obtained from the subroutine:
Table Entry Offset
~
Dx [4:7]
=
$8
=
11
Interpolation Fraction
~
Dx [0:3]
=
$D
=
13
Thus, Y is calculated as follows:
MOTOROLA
4-200
Y
=
80
+
(13 (64 - 80)) / 16
=
67
INSTRUCTION SET CPU32 REFERENCE MANUAL