c6d25d8d |
1 | /* |
2 | * big5enc.c - multibyte encoding of Big5 |
3 | */ |
4 | |
5 | #ifndef ENUM_CHARSETS |
6 | |
7 | #include "charset.h" |
8 | #include "internal.h" |
9 | |
10 | /* |
11 | * Big5 has no associated data, so `charset' may be ignored. |
12 | */ |
13 | |
14 | static void read_big5(charset_spec const *charset, long int input_chr, |
15 | charset_state *state, |
16 | void (*emit)(void *ctx, long int output), void *emitctx) |
17 | { |
18 | UNUSEDARG(charset); |
19 | |
20 | /* |
21 | * For reading Big5, state->s0 simply contains the single |
22 | * stored lead byte when we are half way through a double-byte |
23 | * character, or 0 if we aren't. |
24 | */ |
25 | |
26 | if (state->s0 == 0) { |
27 | if (input_chr >= 0xA1 && input_chr <= 0xFE) { |
28 | /* |
29 | * Lead byte. Just store it. |
30 | */ |
31 | state->s0 = input_chr; |
32 | } else { |
33 | /* |
34 | * Anything else we pass straight through unchanged. |
35 | */ |
36 | emit(emitctx, input_chr); |
37 | } |
38 | } else { |
39 | /* |
40 | * We have a stored lead byte. We expect a valid followup |
41 | * byte. |
42 | */ |
43 | if ((input_chr >= 0x40 && input_chr <= 0x7E) || |
44 | (input_chr >= 0xA1 && input_chr <= 0xFE)) { |
45 | emit(emitctx, big5_to_unicode(state->s0 - 0xA1, input_chr - 0x40)); |
46 | } else { |
47 | emit(emitctx, ERROR); |
48 | } |
49 | state->s0 = 0; |
50 | } |
51 | } |
52 | |
53 | /* |
54 | * Big5 is a stateless multi-byte encoding (in the sense that just |
55 | * after any character has been completed, the state is always the |
56 | * same); hence when writing it, there is no need to use the |
57 | * charset_state. |
58 | */ |
59 | |
60 | static int write_big5(charset_spec const *charset, long int input_chr, |
61 | charset_state *state, |
62 | void (*emit)(void *ctx, long int output), void *emitctx) |
63 | { |
64 | UNUSEDARG(charset); |
65 | UNUSEDARG(state); |
66 | |
67 | if (input_chr == -1) |
68 | return TRUE; /* stateless; no cleanup required */ |
69 | |
70 | if (input_chr < 0x80) { |
71 | emit(emitctx, input_chr); |
72 | return TRUE; |
73 | } else { |
74 | int r, c; |
75 | if (unicode_to_big5(input_chr, &r, &c)) { |
76 | emit(emitctx, r + 0xA1); |
77 | emit(emitctx, c + 0x40); |
78 | return TRUE; |
79 | } else { |
80 | return FALSE; |
81 | } |
82 | } |
83 | } |
84 | |
85 | const charset_spec charset_CS_BIG5 = { |
86 | CS_BIG5, read_big5, write_big5, NULL |
87 | }; |
88 | |
89 | #else /* ENUM_CHARSETS */ |
90 | |
91 | ENUM_CHARSET(CS_BIG5) |
92 | |
93 | #endif /* ENUM_CHARSETS */ |