CJKV Information Processing, 2nd Edition

Code Conversion Algorithms

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581

Converting ISO-2022 to EUC is a simple matter of using the following two assignment

statements in C:

p1 += 128;

p2 += 128;

ese assignment statements have an eect of adding 128 (8) to the current values of

the variables p1 and p2. ese statements could also have been written as follows:

p1 = p1 + 128;

p2 = p2 + 128;

Both styles perform the same task. C (and other programming languages) has a shorthand

method for doing these sort of variable assignments. ere are even shorthand methods

for turning the eighth bit on or o.

Next, converting EUC to ISO-2022 requires the following two statements (or their

equivalent):

p1 -= 128;

p2 -= 128;

ese assignment statements have an eect of subtracting 128 (8) from the current

value of the variables p1 and p2. at’s really all there is to do.

One dicult issue to contend with is how to handle half-width katakana, which can be

represented in EUC-JP encoding using code set 2, but have no ocial representation in

ISO-2022-JP encoding. I suggest that they be converted into their full-width counterparts

(see the section later in this chapter entitled “Half- to Full-Width Katakana Conversion—

in Java”).

Conversion Between ISO-2022 and Row-Cell

Conversion from ISO-2022 to Row-Cell is a matter of subtracting 32 (2) from each

of the ISO-2022 bytes.

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Similarly, conversion from Row-Cell to ISO-2022 is a matter of

adding ...