X-Git-Url: https://git.distorted.org.uk/~mdw/sgt/charset/blobdiff_plain/294941fada5003140ab339ee6d85e0a5af76f151..HEAD:/iso2022.c diff --git a/iso2022.c b/iso2022.c index 9a11a31..6e527dd 100644 --- a/iso2022.c +++ b/iso2022.c @@ -2,11 +2,10 @@ * iso2022.c - support for ISO/IEC 2022 (alias ECMA-35). * * This isn't a complete implementation of ISO/IEC 2022, but it's - * close. It only handles decoding, because a fully general encoder - * isn't really useful. It can decode 8-bit and 7-bit versions, with - * support for single-byte and multi-byte character sets, all four - * containers (G0, G1, G2, and G3), using both single-shift and - * locking-shift sequences. + * close. It can decode 8-bit and 7-bit versions, with support for + * single-byte and multi-byte character sets, all four containers + * (G0, G1, G2, and G3), using both single-shift and locking-shift + * sequences. * * The general principle is that any valid ISO/IEC 2022 sequence * should either be correctly decoded or should emit an ERROR. The @@ -22,6 +21,7 @@ #ifndef ENUM_CHARSETS #include +#include #include "charset.h" #include "internal.h" @@ -35,52 +35,261 @@ enum {S4, S6, M4, M6}; +static long int emacs_big5_1_to_unicode(int, int); +static long int emacs_big5_2_to_unicode(int, int); +static int unicode_to_emacs_big5(long int, int *, int *, int *); +static long int cns11643_1_to_unicode(int, int); +static long int cns11643_2_to_unicode(int, int); +static long int cns11643_3_to_unicode(int, int); +static long int cns11643_4_to_unicode(int, int); +static long int cns11643_5_to_unicode(int, int); +static long int cns11643_6_to_unicode(int, int); +static long int cns11643_7_to_unicode(int, int); static long int null_dbcs_to_unicode(int, int); +static int unicode_to_null_dbcs(long int, int *, int *); + +typedef int (*to_dbcs_t)(long int, int *, int *); +typedef int (*to_dbcs_planar_t)(long int, int *, int *, int *); + +/* + * These macros cast between to_dbcs_planar_t and to_dbcs_t, in + * such a way as to cause a compile-time error if the input is not + * of the appropriate type. + * + * Defining these portably is quite fiddly. My first effort was as + * follows: + * #define DEPLANARISE(x) ( (x) == (to_dbcs_planar_t)NULL, (to_dbcs_t)(x) ) + * + * so that the comparison on the left of the comma provokes the + * type check error, and the cast on the right is the actual + * desired result. + * + * gcc was entirely happy with this. However, when used in a static + * initialiser, MSVC objected - justifiably - that the first half + * of the comma expression wasn't constant and thus the expression + * as a whole was not a constant expression. We can get round this + * by enclosing the comparison in `sizeof', so that it isn't + * actually evaluated. + * + * But then we run into a second problem, which is that C actually + * disallows the use of the comma operator within a constant + * expression for any purpose at all! Presumably this is on the + * basis that its purpose is to have side effects and constant + * expressions can't; unfortunately, this specific case is one in + * which the desired side effect is a compile-time rather than a + * run-time one. + * + * We are permitted to use ?:, however, and that works quite well + * since the actual result of the sizeof expression _is_ evaluable + * at compile time. So here's my final answer: + */ +#define TYPECHECK(x,y) ( sizeof((x)) == sizeof((x)) ? (y) : (y) ) +#define DEPLANARISE(x) TYPECHECK((x) == (to_dbcs_planar_t)NULL, (to_dbcs_t)(x)) +#define REPLANARISE(x) TYPECHECK((x) == (to_dbcs_t)NULL, (to_dbcs_planar_t)(x)) + +/* + * Values used in the `enable' field. Each of these identifies a + * class of character sets; we then have a bitmask indicating which + * classes are allowable in a given mode. + * + * These values are currently only checked on output: for input, + * any ISO 2022 we can comprehend at all is considered acceptable. + */ +#define CCS 1 /* CTEXT standard */ +#define COS 2 /* other standard */ +#define CPU 3 /* private use */ +#define CDC 4 /* DOCS for CTEXT */ +#define CDU 5 /* DOCS for UTF-8 */ +#define CNU 31 /* never used */ + +struct iso2022_mode { + int enable_mask; + char ltype, li, lf, rtype, ri, rf; +}; const struct iso2022_subcharset { - char type, i, f; + char type, i, f, enable; int offset; const sbcs_data *sbcs_base; - long int (*dbcs_fn)(int, int); + long int (*from_dbcs)(int, int); + + /* + * If to_dbcs_plane < 0, then to_dbcs is used as expected. + * However, if to_dbcs_plane >= 0, then to_dbcs is expected to + * be cast to a to_dbcs_planar_t before use, and the returned + * plane value (the first int *) must equal to_dbcs_plane. + * + * I'd have preferred to do this by means of a union, but you + * can't initialise a selected field of a union at compile + * time. Function pointer casts are guaranteed to work sensibly + * in ISO C (that is, it's undefined what happens if you call a + * function via the wrong type of pointer, but if you cast it + * back to the right type before calling it then it must work), + * so this is safe if ugly. + */ + to_dbcs_t to_dbcs; + int to_dbcs_plane; /* use to_dbcs_planar iff >= 0 */ } iso2022_subcharsets[] = { - { S4, 0, '0', 0x00, &sbcsdata_CS_DEC_GRAPHICS }, - { S4, 0, '<', 0x80, &sbcsdata_CS_DEC_MCS }, - { S4, 0, 'A', 0x00, &sbcsdata_CS_BS4730 }, - { S4, 0, 'B', 0x00, &sbcsdata_CS_ASCII }, - { S4, 0, 'I', 0x80, &sbcsdata_CS_JISX0201 }, - { S4, 0, 'J', 0x00, &sbcsdata_CS_JISX0201 }, - { S4, 0, '~' }, - { S6, 0, 'A', 0x80, &sbcsdata_CS_ISO8859_1 }, - { S6, 0, 'B', 0x80, &sbcsdata_CS_ISO8859_2 }, - { S6, 0, 'C', 0x80, &sbcsdata_CS_ISO8859_3 }, - { S6, 0, 'D', 0x80, &sbcsdata_CS_ISO8859_4 }, - { S6, 0, 'F', 0x80, &sbcsdata_CS_ISO8859_7 }, - { S6, 0, 'G', 0x80, &sbcsdata_CS_ISO8859_6 }, - { S6, 0, 'H', 0x80, &sbcsdata_CS_ISO8859_8 }, - { S6, 0, 'L', 0x80, &sbcsdata_CS_ISO8859_5 }, - { S6, 0, 'M', 0x80, &sbcsdata_CS_ISO8859_9 }, - { S6, 0, 'T', 0x80, &sbcsdata_CS_ISO8859_11 }, - { S6, 0, 'V', 0x80, &sbcsdata_CS_ISO8859_10 }, - { S6, 0, 'Y', 0x80, &sbcsdata_CS_ISO8859_13 }, - { S6, 0, '_', 0x80, &sbcsdata_CS_ISO8859_14 }, - { S6, 0, 'b', 0x80, &sbcsdata_CS_ISO8859_15 }, - { S6, 0, 'f', 0x80, &sbcsdata_CS_ISO8859_16 }, - { S6, 0, '~' }, /* empty 96-set */ + /* + * We list these subcharsets in preference order for output. + * Since the best-defined use of ISO 2022 output is compound + * text, we'll use a preference order which matches that. So we + * begin with the charsets defined in the compound text spec. + */ + { S4, 0, 'B', CCS, 0x00, &sbcsdata_CS_ASCII, NULL, NULL, 0 }, + { S6, 0, 'A', CCS, 0x80, &sbcsdata_CS_ISO8859_1, NULL, NULL, 0 }, + { S6, 0, 'B', CCS, 0x80, &sbcsdata_CS_ISO8859_2, NULL, NULL, 0 }, + { S6, 0, 'C', CCS, 0x80, &sbcsdata_CS_ISO8859_3, NULL, NULL, 0 }, + { S6, 0, 'D', CCS, 0x80, &sbcsdata_CS_ISO8859_4, NULL, NULL, 0 }, + { S6, 0, 'F', CCS, 0x80, &sbcsdata_CS_ISO8859_7, NULL, NULL, 0 }, + { S6, 0, 'G', CCS, 0x80, &sbcsdata_CS_ISO8859_6, NULL, NULL, 0 }, + { S6, 0, 'H', CCS, 0x80, &sbcsdata_CS_ISO8859_8, NULL, NULL, 0 }, + { S6, 0, 'L', CCS, 0x80, &sbcsdata_CS_ISO8859_5, NULL, NULL, 0 }, + { S6, 0, 'M', CCS, 0x80, &sbcsdata_CS_ISO8859_9, NULL, NULL, 0 }, + { S4, 0, 'I', CCS, 0x80, &sbcsdata_CS_JISX0201, NULL, NULL, 0 }, + { S4, 0, 'J', CCS, 0x00, &sbcsdata_CS_JISX0201, NULL, NULL, 0 }, + { M4, 0, 'A', CCS, -0x21, 0, &gb2312_to_unicode, &unicode_to_gb2312, -1 }, + { M4, 0, 'B', CCS, -0x21, 0, &jisx0208_to_unicode, &unicode_to_jisx0208, -1 }, + { M4, 0, 'C', CCS, -0x21, 0, &ksx1001_to_unicode, &unicode_to_ksx1001, -1 }, + { M4, 0, 'D', CCS, -0x21, 0, &jisx0212_to_unicode, &unicode_to_jisx0212, -1 }, + + /* + * Next, other reasonably standard things: the rest of the ISO + * 8859 sets, UK-ASCII, and CNS 11643. + */ + { S6, 0, 'T', COS, 0x80, &sbcsdata_CS_ISO8859_11, NULL, NULL, 0 }, + { S6, 0, 'V', COS, 0x80, &sbcsdata_CS_ISO8859_10, NULL, NULL, 0 }, + { S6, 0, 'Y', COS, 0x80, &sbcsdata_CS_ISO8859_13, NULL, NULL, 0 }, + { S6, 0, '_', COS, 0x80, &sbcsdata_CS_ISO8859_14, NULL, NULL, 0 }, + { S6, 0, 'b', COS, 0x80, &sbcsdata_CS_ISO8859_15, NULL, NULL, 0 }, + { S6, 0, 'f', COS, 0x80, &sbcsdata_CS_ISO8859_16, NULL, NULL, 0 }, + { S4, 0, 'A', COS, 0x00, &sbcsdata_CS_BS4730, NULL, NULL, 0 }, + { M4, 0, 'G', COS, -0x21, 0, &cns11643_1_to_unicode, DEPLANARISE(&unicode_to_cns11643), 0 }, + { M4, 0, 'H', COS, -0x21, 0, &cns11643_2_to_unicode, DEPLANARISE(&unicode_to_cns11643), 1 }, + { M4, 0, 'I', COS, -0x21, 0, &cns11643_3_to_unicode, DEPLANARISE(&unicode_to_cns11643), 2 }, + { M4, 0, 'J', COS, -0x21, 0, &cns11643_4_to_unicode, DEPLANARISE(&unicode_to_cns11643), 3 }, + { M4, 0, 'K', COS, -0x21, 0, &cns11643_5_to_unicode, DEPLANARISE(&unicode_to_cns11643), 4 }, + { M4, 0, 'L', COS, -0x21, 0, &cns11643_6_to_unicode, DEPLANARISE(&unicode_to_cns11643), 5 }, + { M4, 0, 'M', COS, -0x21, 0, &cns11643_7_to_unicode, DEPLANARISE(&unicode_to_cns11643), 6 }, + + /* + * Private-use designations: DEC private sets and Emacs's Big5 + * abomination. + */ + { S4, 0, '0', CPU, 0x00, &sbcsdata_CS_DEC_GRAPHICS, NULL, NULL, 0 }, + { S4, 0, '<', CPU, 0x80, &sbcsdata_CS_DEC_MCS, NULL, NULL, 0 }, + { M4, 0, '0', CPU, -0x21, 0, &emacs_big5_1_to_unicode, DEPLANARISE(&unicode_to_emacs_big5), 1 }, + { M4, 0, '1', CPU, -0x21, 0, &emacs_big5_2_to_unicode, DEPLANARISE(&unicode_to_emacs_big5), 2 }, + + /* + * Ben left this conditioned out without explanation, + * presumably on the grounds that we don't have a translation + * table for it. + */ #if 0 - { M4, 0, '@' }, /* JIS C 6226-1978 */ + { M4, 0, '@', CNU }, /* JIS C 6226-1978 */ #endif - { M4, 0, 'A', -0x21, 0, &gb2312_to_unicode }, - { M4, 0, 'B', -0x21, 0, &jisx0208_to_unicode }, - { M4, 0, 'C', -0x21, 0, &ksx1001_to_unicode }, - { M4, 0, 'D', -0x21, 0, &jisx0212_to_unicode }, - { M4, 0, '~', 0, 0, &null_dbcs_to_unicode }, /* empty 94^n-set */ - { M6, 0, '~', 0, 0, &null_dbcs_to_unicode }, /* empty 96^n-set */ + + /* + * Finally, fallback entries for null character sets. + */ + { S4, 0, '~', CNU, 0, NULL, NULL, NULL, 0 }, + { S6, 0, '~', CNU, 0, NULL, NULL, NULL, 0 }, /* empty 96-set */ + { M4, 0, '~', CNU, 0, 0, &null_dbcs_to_unicode, &unicode_to_null_dbcs, -1 }, /* empty 94^n-set */ + { M6, 0, '~', CNU, 0, 0, &null_dbcs_to_unicode, &unicode_to_null_dbcs, -1 }, /* empty 96^n-set */ }; static long int null_dbcs_to_unicode(int r, int c) { + UNUSEDARG(r); + UNUSEDARG(c); return ERROR; } +static int unicode_to_null_dbcs(long int unicode, int *r, int *c) +{ + UNUSEDARG(unicode); + UNUSEDARG(r); + UNUSEDARG(c); + return 0; /* failed to convert anything */ +} + +/* + * Emacs encodes Big5 in COMPOUND_TEXT as two 94x94 character sets. + * We treat Big5 as a 94x191 character set with a bunch of undefined + * columns in the middle, so we have to mess around a bit to make + * things fit. + */ + +static long int emacs_big5_1_to_unicode(int r, int c) +{ + unsigned long s; + s = r * 94 + c; + r = s / 157; + c = s % 157; + if (c >= 64) c += 34; /* Skip over the gap */ + return big5_to_unicode(r, c); +} + +static long int emacs_big5_2_to_unicode(int r, int c) +{ + unsigned long s; + s = r * 94 + c; + r = s / 157 + 40; + c = s % 157; + if (c >= 64) c += 34; /* Skip over the gap */ + return big5_to_unicode(r, c); +} + +static int unicode_to_emacs_big5(long int unicode, int *p, int *r, int *c) +{ + int rr, cc, s; + if (!unicode_to_big5(unicode, &rr, &cc)) + return 0; + if (cc >= 64) { + cc -= 34; + assert(cc >= 64); + } + s = rr * 157 + cc; + if (s >= 40*157) { + *p = 2; + s -= 40*157; + } else { + *p = 1; + } + *r = s / 94; + *c = s % 94; + return 1; +} + +/* Wrappers for cns11643_to_unicode() */ +static long int cns11643_1_to_unicode(int r, int c) +{ + return cns11643_to_unicode(0, r, c); +} +static long int cns11643_2_to_unicode(int r, int c) +{ + return cns11643_to_unicode(1, r, c); +} +static long int cns11643_3_to_unicode(int r, int c) +{ + return cns11643_to_unicode(2, r, c); +} +static long int cns11643_4_to_unicode(int r, int c) +{ + return cns11643_to_unicode(3, r, c); +} +static long int cns11643_5_to_unicode(int r, int c) +{ + return cns11643_to_unicode(4, r, c); +} +static long int cns11643_6_to_unicode(int r, int c) +{ + return cns11643_to_unicode(5, r, c); +} +static long int cns11643_7_to_unicode(int r, int c) +{ + return cns11643_to_unicode(6, r, c); +} /* States, or "what we're currently accumulating". */ enum { @@ -90,10 +299,11 @@ enum { ESCSEQ, /* Accumulating an escape sequence */ ESCDROP, /* Discarding an escape sequence */ ESCPASS, /* Passing through an escape sequence */ - DOCSUTF8 /* DOCSed into UTF-8 */ + DOCSUTF8, /* DOCSed into UTF-8 */ + DOCSCTEXT /* DOCSed into a COMPOUND_TEXT extended segment */ }; -#if 1 +#if 0 #include static void dump_state(charset_state *s) { @@ -119,7 +329,7 @@ static void designate(charset_state *state, int container, assert(container >= 0 && container <= 3); assert(type == S4 || type == S6 || type == M4 || type == M6); - for (i = 0; i <= lenof(iso2022_subcharsets); i++) { + for (i = 0; i < lenof(iso2022_subcharsets); i++) { if (iso2022_subcharsets[i].type == type && iso2022_subcharsets[i].i == ibyte && iso2022_subcharsets[i].f == fbyte) { @@ -141,7 +351,6 @@ static void do_utf8(long int input_chr, void *emitctx) { charset_state ustate; - charset_spec const *utf8; ustate.s1 = 0; ustate.s0 = state->s0 & 0x03ffffffL; @@ -182,12 +391,128 @@ static void docs_utf8(long int input_chr, state->s0 = (state->s0 & ~0x0c000000L) | (retstate << 26); } +struct ctext_encoding { + char const *name; + char octets_per_char, enable; + charset_spec const *subcs; +}; + +/* + * In theory, this list is in , + * but XLib appears to have its own ideas, and encodes these three + * (as of X11R6.8.2) + */ + +extern charset_spec const charset_CS_ISO8859_14; +extern charset_spec const charset_CS_ISO8859_15; +extern charset_spec const charset_CS_BIG5; + +static struct ctext_encoding const ctext_encodings[] = { + { "big5-0\2", 0 /* variable */, CDC, &charset_CS_BIG5 }, + { "iso8859-14\2", 1, CDC, &charset_CS_ISO8859_14 }, + { "iso8859-15\2", 1, CDC, &charset_CS_ISO8859_15 } +}; + +static void docs_ctext(long int input_chr, + charset_state *state, + void (*emit)(void *ctx, long int output), + void *emitctx) +{ + /* + * s0[27:26] = first entry in ctext_encodings that matches + * s0[25:22] = number of characters successfully matched, 0xf if all + * s0[21:8] count the number of octets left in the segment + * s0[7:0] are for sub-charset use + */ + int n = (state->s0 >> 22) & 0xf, i = (state->s0 >> 26) & 3, oi = i, j; + int length = (state->s0 >> 8) & 0x3fff; + + /* + * Note that we do not bother checking the octets-per-character + * byte against the selected charset when reading. It's + * extremely unlikely that this code will ever have to deal + * with two charset identifiers with the same name and + * different octets-per-character values! If it ever happens, + * we'll have to edit this file anyway so we can modify the + * code then... + */ + + if (!length) { + /* Haven't read length yet */ + if ((state->s0 & 0xff) == 0) + /* ... or even the first byte */ + state->s0 |= input_chr; + else { + length = (state->s0 & 0x7f) * 0x80 + (input_chr & 0x7f); + if (length == 0) + state->s0 = 0; + else + state->s0 = (state->s0 & 0xf0000000) | (length << 8); + } + return; + } + + j = i; + if (n == 0xe) { + /* Skipping unknown encoding. Look out for STX. */ + if (input_chr == 2) + state->s0 = (state->s0 & 0xf0000000) | (i << 26) | (0xf << 22); + } else if (n != 0xf) { + while ((unsigned)j < lenof(ctext_encodings) && + !memcmp(ctext_encodings[j].name, + ctext_encodings[oi].name, n)) { + if (ctext_encodings[j].name[n] < input_chr) + i = ++j; + else + break; + } + if ((unsigned)i >= lenof(ctext_encodings) || + memcmp(ctext_encodings[i].name, + ctext_encodings[oi].name, n) || + ctext_encodings[i].name[n] != input_chr) { + /* Doom! We haven't heard of this encoding */ + i = lenof(ctext_encodings); + n = 0xe; + } else { + /* + * Otherwise, we have found an additional character in our + * encoding name. See if we have reached the _end_ of our + * name. + */ + n++; + if (!ctext_encodings[i].name[n]) + n = 0xf; + } + /* + * Failing _that_, we simply update our encoding-name- + * tracking state. + */ + assert(i < 4 && n < 16); + state->s0 = (state->s0 & 0xf0000000) | (i << 26) | (n << 22); + } else { + if ((unsigned)i >= lenof(ctext_encodings)) + emit(emitctx, ERROR); + else { + charset_state substate; + charset_spec const *subcs = ctext_encodings[i].subcs; + substate.s1 = 0; + substate.s0 = state->s0 & 0xff; + subcs->read(subcs, input_chr, &substate, emit, emitctx); + state->s0 = (state->s0 & ~0xff) | (substate.s0 & 0xff); + } + } + if (!--length) + state->s0 = 0; + else + state->s0 = (state->s0 &~0x003fff00) | (length << 8); +} static void read_iso2022(charset_spec const *charset, long int input_chr, - charset_state *state, - void (*emit)(void *ctx, long int output), - void *emitctx) + charset_state *state, + void (*emit)(void *ctx, long int output), + void *emitctx) { + struct iso2022_mode const *mode = (struct iso2022_mode *)charset->data; /* dump_state(state); */ /* @@ -215,9 +540,9 @@ static void read_iso2022(charset_spec const *charset, long int input_chr, #define LEFT 30 #define RIGHT 28 #define LOCKING_SHIFT(n,side) \ - (state->s1 = (state->s1 & ~(3L<<(side))) | ((n ## L)<<(side))) -#define MODE ((state->s0 & 0xe0000000L) >> 29) -#define ENTER_MODE(m) (state->s0 = (state->s0 & ~0xe0000000L) | ((m)<<29)) + (state->s1 = (state->s1 & ~(3UL<<(side))) | ((n ## UL)<<(side))) +#define MODE ((state->s0 & 0xe0000000UL) >> 29) +#define ENTER_MODE(m) (state->s0 = (state->s0 & ~0xe0000000UL) | ((unsigned long)(m)<<29)) #define SINGLE_SHIFT(n) ENTER_MODE(SS2CHAR - 2 + (n)) #define ASSERT_IDLE do { \ if (state->s0 != 0) emit(emitctx, ERROR); \ @@ -231,8 +556,8 @@ static void read_iso2022(charset_spec const *charset, long int input_chr, */ LOCKING_SHIFT(0, LEFT); LOCKING_SHIFT(1, RIGHT); - designate(state, 0, S4, 0, 'B'); - designate(state, 1, S4, 0, 'B'); + designate(state, 0, mode->ltype, mode->li, mode->lf); + designate(state, 1, mode->rtype, mode->ri, mode->rf); designate(state, 2, S4, 0, 'B'); designate(state, 3, S4, 0, 'B'); } @@ -241,6 +566,10 @@ static void read_iso2022(charset_spec const *charset, long int input_chr, docs_utf8(input_chr, state, emit, emitctx); return; } + if (MODE == DOCSCTEXT) { + docs_ctext(input_chr, state, emit, emitctx); + return; + } if ((input_chr & 0x60) == 0x00) { /* C0 or C1 control */ @@ -300,8 +629,9 @@ static void read_iso2022(charset_spec const *charset, long int input_chr, return; } else { emit(emitctx, - subcs->dbcs_fn(((state->s0 >> 16) & 0x7f) + subcs->offset, - input_7bit + subcs->offset)); + subcs->from_dbcs(((state->s0 >> 16) & 0x7f) + + subcs->offset, + input_7bit + subcs->offset)); } } else { if ((state->s0 & 0x00ff0000L) != 0) @@ -456,6 +786,13 @@ static void read_iso2022(charset_spec const *charset, long int input_chr, break; } break; + case '/': + switch (input_chr) { + case '1': case '2': + ENTER_MODE(DOCSCTEXT); + break; + } + break; } break; default: @@ -469,16 +806,428 @@ static void read_iso2022(charset_spec const *charset, long int input_chr, } } +static void oselect(charset_state *state, int i, int right, + void (*emit)(void *ctx, long int output), + void *emitctx) +{ + int shift = (right ? 31-7 : 31-7-7); + struct iso2022_subcharset const *subcs = &iso2022_subcharsets[i]; + + if (((state->s1 >> shift) & 0x7F) != (unsigned)i) { + state->s1 &= ~(0x7FL << shift); + state->s1 |= (i << shift); + + if (emit) { + emit(emitctx, ESC); + if (subcs->type == M4 || subcs->type == M6) + emit(emitctx, '$'); + if (subcs->type == S6 || subcs->type == M6) { + assert(right); + emit(emitctx, '-'); + } else if (right) { + emit(emitctx, ')'); + } else { + emit(emitctx, '('); + } + if (subcs->i) + emit(emitctx, subcs->i); + emit(emitctx, subcs->f); + } + } +} + +static void docs_char(charset_state *state, + void (*emit)(void *ctx, long int output), + void *emitctx, int cset, char *data, int datalen) +{ + int curr_cset, currlen, i; + + /* + * cset is the index into ctext_encodings[]. It can also be -1 + * to mean DOCS UTF-8, or -2 to mean no DOCS (ordinary 2022). + * In the latter case, `chr' is ignored. + */ + + /* + * First, terminate a DOCS segment if necessary. We always have + * to terminate a DOCS segment if one is active and we're about + * to switch to a different one; we might also have to + * terminate a length-encoded DOCS segment if we've run out of + * storage space to accumulate characters in it. + */ + curr_cset = ((state->s1 >> 14) & 7) - 2; + currlen = ((state->s1 >> 11) & 7); + if ((curr_cset != -2 && curr_cset != cset) || + (curr_cset >= 0 && currlen + datalen > 5)) { + if (curr_cset == -1) { + /* + * Terminating DOCS UTF-8 is easy. + */ + emit(emitctx, ESC); + emit(emitctx, '%'); + emit(emitctx, '@'); + } else { + int len; + + /* + * To terminate a length-encoded DOCS segment we must + * actually output the whole thing. + */ + emit(emitctx, ESC); + emit(emitctx, '%'); + emit(emitctx, '/'); + emit(emitctx, '0' + ctext_encodings[curr_cset].octets_per_char); + len = currlen + datalen + + strlen(ctext_encodings[curr_cset].name); + assert(len < (1 << 14)); + emit(emitctx, 0x80 | ((len >> 7) & 0x7F)); + emit(emitctx, 0x80 | ((len ) & 0x7F)); + /* The name stored in ctext_encodings[] includes the trailing \2 */ + for (i = 0; ctext_encodings[curr_cset].name[i]; i++) + emit(emitctx, ctext_encodings[curr_cset].name[i]); + for (i = 0; i < currlen; i++) + emit(emitctx, + (i == 0 ? state->s1 : state->s0 >> (8*(4-i))) & 0xFF); + for (i = 0; i < datalen; i++) + emit(emitctx, data[i]); + + /* + * We've now dealt with the input data, so clear it so + * we don't try to do so again below. + */ + datalen = 0; + } + curr_cset = -2; + } + + /* + * Now, start a DOCS segment if necessary. + */ + if (curr_cset != cset) { + assert(cset != -2); + if (cset == -1) { + /* + * Start DOCS UTF-8. + */ + emit(emitctx, ESC); + emit(emitctx, '%'); + emit(emitctx, 'G'); + } else { + /* + * Starting a length-encoded DOCS segment is simply a + * matter of setting our stored length counter to zero. + */ + currlen = 0; + state->s1 &= ~(7 << 11); + state->s1 &= ~0xFF; + state->s0 = 0; + } + } + state->s1 &= ~(7 << 14); + assert((cset+2) >= 0 && (cset+2) < 8); + state->s1 |= ((cset+2) << 14); + + /* + * Now we're in the right DOCS state. Actually deal with the + * input data, if we haven't already done so above. + */ + if (datalen > 0) { + assert(cset != 2); + if (cset == -1) { + /* + * In DOCS UTF-8, we output data as soon as we get it. + */ + for (i = 0; i < datalen; i++) + emit(emitctx, data[i]); + } else { + /* + * In length-encoded DOCS, we just store our data and + * bide our time. It'll all be output when we fill up + * or switch to another character set. + */ + assert(currlen + datalen <= 5); /* overflow handled already */ + for (i = 0; i < datalen; i++) { + if (currlen + i == 0) + state->s1 |= data[i] & 0xFF; + else + state->s0 |= (data[i] & 0xFF) << (8*(4-(currlen+i))); + } + currlen += datalen; + assert(currlen >= 0 && currlen < 8); + state->s1 &= ~(7 << 11); + state->s1 |= (currlen << 11); + } + } +} + +static void write_to_pointer(void *ctx, long int output) +{ + char **ptr = (char **)ctx; + *(*ptr)++ = output; +} + +/* + * Writing full ISO-2022 is not useful in very many circumstances. + * One of the few situations in which it _is_ useful is generating + * X11 COMPOUND_TEXT; therefore, this writing function will obey + * the compound text restrictions and hence output the subset of + * ISO-2022 that's usable in that context. + * + * The subset in question is roughly that we use GL/GR for G0/G1 + * always, and that the _only_ escape sequences we output (other + * than the occasional DOCS) are those which designate different + * subcharsets into G0 and G1. There are additional constraints + * about which things go in which container; see below. + * + * FIXME: this wants some decent tests to be written, and also the + * exact output policy for compound text wants thinking about more + * carefully. + */ static int write_iso2022(charset_spec const *charset, long int input_chr, charset_state *state, void (*emit)(void *ctx, long int output), void *emitctx) { + int i; + struct iso2022_subcharset const *subcs; + struct iso2022_mode const *mode = (struct iso2022_mode *)charset->data; + to_dbcs_planar_t last_planar_dbcs = NULL; + int last_p, last_r, last_c; + long int c1, c2; + + /* + * For output, I allocate the state variables as follows: + * + * s1[31] == 1 if output state has been initialised + * s1[30:24] == G1 charset (always in GR) + * s1[23:17] == G0 charset (always in GL) + * s1[16:14] == DOCS index plus 2 (because -1 and -2 are special) + * s1[13:11] == number of DOCS accumulated characters (up to five) + * s1[7:0] + s0[31:0] == DOCS collected characters + */ + + if (!state->s1) { + state->s0 = 0x00000000UL; + state->s1 = 0x80000000UL; + /* + * Start with US-ASCII in GL and also in GR. + */ + for (i = 0; (unsigned)i < lenof(iso2022_subcharsets); i++) { + subcs = &iso2022_subcharsets[i]; + if (subcs->type == mode->ltype && + subcs->i == mode->li && + subcs->f == mode->lf) + oselect(state, i, FALSE, NULL, NULL); + if (subcs->type == mode->rtype && + subcs->i == mode->ri && + subcs->f == mode->rf) + oselect(state, i, TRUE, NULL, NULL); + } + } + + if (input_chr == -1) { + /* + * Special case: reset encoding state. + */ + docs_char(state, emit, emitctx, -2, NULL, 0); /* leave DOCS */ + + for (i = 0; (unsigned)i < lenof(iso2022_subcharsets); i++) { + subcs = &iso2022_subcharsets[i]; + if (subcs->type == mode->ltype && + subcs->i == mode->li && + subcs->f == mode->lf) + oselect(state, i, FALSE, emit, emitctx); + if (subcs->type == mode->rtype && + subcs->i == mode->ri && + subcs->f == mode->rf) + oselect(state, i, TRUE, emit, emitctx); + } + return TRUE; + } + + /* + * Special-case characters: Space, Delete, and anything in C0 + * or C1 are output unchanged. + */ + if (input_chr <= 0x20 || (input_chr >= 0x7F && input_chr < 0xA0)) { + emit(emitctx, input_chr); + return TRUE; + } + + /* + * Analyse the input character and work out which subcharset it + * belongs to. + */ + for (i = 0; (unsigned)i < lenof(iso2022_subcharsets); i++) { + subcs = &iso2022_subcharsets[i]; + if (!(mode->enable_mask & (1 << subcs->enable))) + continue; /* this charset is disabled */ + if (subcs->sbcs_base) { + c1 = sbcs_from_unicode(subcs->sbcs_base, input_chr); + c1 -= subcs->offset; + if (c1 >= 0x20 && c1 <= 0x7f) { + c2 = 0; + break; + } + } else if (subcs->to_dbcs) { + if (subcs->to_dbcs_plane >= 0) { + /* + * Since multiplanar DBCSes almost by definition + * involve several entries in iso2022_subcharsets + * with the same to_dbcs function and different + * plane values, we remember the last such function + * we called and what its result was, so that we + * don't (for example) have to call + * unicode_to_cns11643 seven times. + */ + if (last_planar_dbcs != REPLANARISE(subcs->to_dbcs)) { + last_planar_dbcs = REPLANARISE(subcs->to_dbcs); + if (!last_planar_dbcs(input_chr, + &last_p, &last_r, &last_c)) + last_p = -1; + } + } else { + last_p = subcs->to_dbcs_plane; + if (!subcs->to_dbcs(input_chr, &last_r, &last_c)) + last_p = 0; /* cannot match since to_dbcs_plane<0 */ + } + + if (last_p == subcs->to_dbcs_plane) { + c1 = last_r - subcs->offset; + c2 = last_c - subcs->offset; + assert(c1 >= 0x20 && c1 <= 0x7f); + assert(c2 >= 0x20 && c2 <= 0x7f); + break; + } + } + } + + if ((unsigned)i < lenof(iso2022_subcharsets)) { + int right; + + /* + * Our character is represented by c1 (and possibly also + * c2) in subcharset `subcs'. So now we must decide whether + * to designate that character set into G0/GL or G1/GR. + * + * Any S6 or M6 subcharset has to go in GR because it won't + * fit in GL. In addition, the compound text rules state + * that any single-byte subcharset defined as the + * right-hand half of some SBCS must go in GR. + * + * M4 subcharsets can go in either half according to the + * rules. I choose to put them in GR always because it's a + * simple policy with reasonable behaviour (facilitates + * switching between them and ASCII). + */ + right = (subcs->type == S6 || subcs->type == M6 || subcs->type == M4 || + (subcs->sbcs_base && subcs->offset == 0x80)); + + /* + * If we're in a DOCS mode, leave it. + */ + docs_char(state, emit, emitctx, -2, NULL, 0); + + /* + * If this subcharset is not already selected in that + * container, select it. + */ + oselect(state, i, right, emit, emitctx); + + /* + * Now emit the actual characters. + */ + if (right) { + assert(c1 >= 0x20 && c1 <= 0x7f); + emit(emitctx, c1 | 0x80); + if (c2) { + assert(c2 >= 0x20 && c2 <= 0x7f); + emit(emitctx, c2 | 0x80); + } + } else { + assert(c1 > 0x20 && c1 < 0x7f); + emit(emitctx, c1); + if (c2) { + assert(c2 > 0x20 && c2 < 0x7f); + emit(emitctx, c2); + } + } + + return TRUE; + } + + /* + * Fall back to DOCS. + */ + { + char data[10]; + char *p = data; + int i, cs; + + cs = -2; /* means failure */ + + for (i = 0; (unsigned)i <= lenof(ctext_encodings); i++) { + charset_state substate; + charset_spec const *subcs = ctext_encodings[i].subcs; + + /* + * We assume that all character sets dealt with by DOCS + * are stateless for output purposes. + */ + substate.s1 = substate.s0 = 0; + p = data; + + if ((unsigned)i < lenof(ctext_encodings)) { + if ((mode->enable_mask & (1 << ctext_encodings[i].enable)) && + subcs->write(subcs, input_chr, &substate, + write_to_pointer, &p)) { + cs = i; + break; + } + } else { + if ((mode->enable_mask & (1 << CDU)) && + write_utf8(NULL, input_chr, NULL, write_to_pointer, &p)) { + cs = -1; + break; + } + } + } + + if (cs != -2) { + docs_char(state, emit, emitctx, cs, data, p - data); + return TRUE; + } + } + return FALSE; } +/* + * Full ISO 2022 output with all options on. Not entirely sure what + * if anything this is useful for, but here it is anyway. All + * output character sets and DOCS variants are permitted; all + * containers start out with ASCII in them. + */ +static const struct iso2022_mode iso2022_all = { + (1<