The Annoyance Filter.pdf - Fourmilab

68 SHIFT-JIS DECODER ANNOYANCE-FILTER §77
77. We test for the first byte we’ve read being in the range which denotes a two byte character. If
so, read the second byte of the character, validating that it is within the ranges permitted for second
bytes, and assemble the 16 bit character from the two bytes.
〈 Check for Shift-JIS two byte character and assemble as required 77 〉 ≡
if (((c1 ≥ # 81) ∧ (c1 ≤ # 9F)) ∨ ((c1 ≥ # E0) ∧ (c1 ≤ # EF)) ∨ ((c1 ≥ # F0) ∧ (c1 ≤ # FC))) {
int c2 = getNextEncodedByte ( );
}
if (c2 ≡ −1) {
ostringstream os ;
os ≪ name ( ) ≪ "_MBCSdecoder:␣Premature␣end␣of␣line␣in␣two␣byte␣character.";
reportDecoderDiagnostic(os );
return −1;
}
if (¬(((c2 ≥ # 40) ∧ (c2 ≤ # 7E)) ∨ ((c2 ≥ # 80) ∧ (c2 ≤ # FC)))) {
ostringstream os ;
os ≪ name ( ) ≪ "_MBCSdecoder:␣Invalid␣second␣byte␣in␣two␣byte␣character:␣""0x" ≪
setiosflags (ios ::uppercase ) ≪ hex ≪ c1 ≪ "␣" ≪ "0x" ≪ c2 ≪ ".";
reportDecoderDiagnostic(os );
return −1;
}
return (c1 ≪ 8) | c2 ;
This code is used in section 76.
78. To permit expansion of Macintosh-specific characters to multiple character replacements, we have
the ability to store the balance of a multiple character sequence in the pending string. If there are any
characters there, return them before obtaining another character from the input stream.
〈 Check for pending characters and return if so 78 〉 ≡
if (¬pending .empty ( )) {
int pc = pending [0];
}
pending = pending .substr (1);
return pc;
This code is used in section 76.