Typewriter User Manual

MOTOROLA MC68340 USER’S MANUAL 5- 31

The table instruction is executed with the following bit pattern in Dx:

31 16 15 0

NOT USED 1010001110000000

Table Entry Offset ⇒ Dx [8:15] = $A3 = 163

Interpolation Fraction ⇒ Dx [0:7] = $80 = 128

Using this information, the table instruction calculates dependent variable Y:

Y = 1669 + (128 (1679 – 1669)) / 256 = 1674

5.3.4.2 TABLE EXAMPLE 2: COMPRESSED TABLE. In Example 2 (see Figure 5-8), the

data from Example 1 has been compressed by limiting the maximum value of the

independent variable. Instead of the range 0 ≤ X = 65535, X is limited to 0 ≤ X ≤ 1023.

The table has been compressed to only five entries, but up to 256 levels of interpolation

are allowed between entries.

256 512 786 1024

INDEPENDENT VARIABLE

DEPENDENT VARIABLE

Figure 5-8. Table Example 2

NOTE

Extreme table compression with many levels of interpolation is

possible only with highly linear functions. The table entries

within the range of interest are listed in Table 5-14.

Frees

cale Semiconductor,

Freescale Semiconductor, Inc.

For More Information On This Product,

Go to: www.freescale.com

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