/*
* iso2022s.c - support for ISO-2022 subset encodings.
*/
#ifndef ENUM_CHARSETS
#include <stdio.h>
#include <string.h>
#include <assert.h>
#include "charset.h"
#include "internal.h"
#include "sbcsdat.h"
#define SO (0x0E)
#define SI (0x0F)
#define ESC (0x1B)
/* Functional description of a single ISO 2022 escape sequence. */
struct iso2022_escape {
char const *sequence;
unsigned long andbits, xorbits;
/*
* For output, these variables help us figure out which escape
* sequences we need to get where we want to be.
*
* `container' should be in the range 0-3, but can also be ORed
* with the bit flag RO to indicate that this is not a
* preferred container to use for this charset during output.
*/
int container, subcharset;
};
#define RO 0x80
struct iso2022 {
/*
* List of escape sequences supported in this subset. Must be
* in ASCII order, so that we can narrow down the list as
* necessary.
*/
const struct iso2022_escape *escapes;/* must be sorted in ASCII order! */
int nescapes;
/*
* We assign indices from 0 upwards to the sub-charsets of a
* given ISO 2022 subset. nbytes[i] tells us how many bytes per
* character are required by sub-charset i. (It's a string
* mainly because that makes it easier to declare in C syntax
* than an int array.)
*/
char const *nbytes;
/*
* The characters in this string are indices-plus-one (so that
* NUL can still terminate) of escape sequences in `escapes'.
* These escapes are output in the given sequence to reset the
* encoding state, unless it turns out that a given escape
* would not change the state at all.
*/
char const *reset;
/*
* Initial value of s1, in case the default container contents
* needs to be something other than charset 0 in all cases.
* (Note that this must have the top bit set!)
*/
unsigned long s1;
/*
* For output, some ISO 2022 subsets _mandate_ an initial shift
* sequence. If so, here it is so we can output it. (For the
* sake of basic sanity we won't bother to _require_ it on
* input, although it should of course be listed under
* `escapes' above so that we ignore it when present.)
*/
char const *initial_sequence;
/*
* Is this an 8-bit ISO 2022 subset?
*/
int eightbit;
/*
* Function calls to do the actual translation.
*/
long int (*to_ucs)(int subcharset, unsigned long bytes);
int (*from_ucs)(long int ucs, int *subcharset, unsigned long *bytes);
};
static void read_iso2022s(charset_spec const *charset, long int input_chr,
charset_state *state,
void (*emit)(void *ctx, long int output),
void *emitctx)
{
struct iso2022 const *iso = (struct iso2022 *)charset->data;
/*
* For reading ISO-2022 subsets, we divide up our state
* variables as follows:
*
* - The top byte of s0 (bits 31:24) indicates, if nonzero,
* that we are part-way through a recognised ISO-2022 escape
* sequence. Five of those bits (31:27) give the index of
* the first member of the escapes list matching what we
* have so far; the remaining three (26:24) give the number
* of characters we have seen so far.
*
* - The top bit of s1 (bit 31) is non-zero at all times, to
* indicate that we have performed any necessary
* initialisation. When we start, we detect a zero s1 and
* respond to it by initialising the default container
* contents.
*
* - The next three bits of s1 (bits 30:28) indicate which
* _container_ is currently selected. This isn't quite as
* simple as it sounds, since we have to preserve memory of
* which of the SI/SO containers we came from when we're
* temporarily in SS2/SS3. Hence, what happens is:
* + bit 28 indicates SI/SO.
* + if we're in an SS2/SS3 container, that's indicated by
* the two bits above that being nonzero and holding
* either 2 or 3.
* + Hence: 0 is SI, 1 is SO, 4 is SS2-from-SI, 5 is
* SS2-from-SO, 6 is SS3-from-SI, 7 is SS3-from-SO.
* + For added fun: in an _8-bit_ ISO 2022 subset, we have
* the further special value 2, which means that we're
* theoretically in SI but the current character being
* accumulated is composed of 8-bit characters and will
* therefore be interpreted as if in SO.
*
* - The next nibble of s1 (27:24) indicates how many bytes
* have been accumulated in the current character.
*
* - The remaining three bytes of s1 are divided into four
* six-bit sections, and each section gives the current
* sub-charset selected in one of the possible containers.
* (Those containers are SI, SO, SS2 and SS3, respectively
* and in order from the bottom of s0 to the top.)
*
* - The bottom 24 bits of s0 give the accumulated character
* data so far.
*
* (Note that this means s1 contains all the parts of the state
* which might need to be operated on by escape sequences.
* Cunning, eh?)
*/
if (!(state->s1 & 0x80000000)) {
state->s1 = iso->s1;
}
/*
* So. Firstly, we process escape sequences, if we're in the
* middle of one or if we see a possible introducer (SI, SO,
* ESC).
*/
if ((state->s0 >> 24) ||
(input_chr == SO || input_chr == SI || input_chr == ESC)) {
int n = (state->s0 >> 24) & 7, i = (state->s0 >> 27), oi = i, j;
/*
* If this is the start of an escape sequence, we might be
* in mid-character. If so, clear the character state and
* emit an error token for the incomplete character.
*/
if (state->s1 & 0x0F000000) {
state->s1 &= ~0x0F000000;
state->s0 &= 0xFF000000;
/*
* If we were in the SS2 or SS3 container, we
* automatically exit it.
*/
if (state->s1 & 0x60000000)
state->s1 &= 0x9FFFFFFF;
emit(emitctx, ERROR);
}
j = i;
while (j < iso->nescapes &&
!memcmp(iso->escapes[j].sequence,
iso->escapes[oi].sequence, n)) {
if (iso->escapes[j].sequence[n] < input_chr)
i = ++j;
else
break;
}
if (i >= iso->nescapes ||
memcmp(iso->escapes[i].sequence,
iso->escapes[oi].sequence, n) ||
iso->escapes[i].sequence[n] != input_chr) {
/*
* This character does not appear in any valid escape
* sequence. Therefore, we must emit all the characters
* we had previously swallowed, plus this one, and
* return to non-escape-sequence state.
*/
for (j = 0; j < n; j++)
emit(emitctx, iso->escapes[oi].sequence[j]);
emit(emitctx, input_chr);
state->s0 = 0;
return;
}
/*
* Otherwise, we have found an additional character in our
* escape sequence. See if we have reached the _end_ of our
* sequence (and therefore must process the sequence).
*/
n++;
if (!iso->escapes[i].sequence[n]) {
state->s0 = 0;
state->s1 &= iso->escapes[i].andbits;
state->s1 ^= iso->escapes[i].xorbits;
return;
}
/*
* Failing _that_, we simply update our escape-sequence-
* tracking state.
*/
assert(i < 32 && n < 8);
state->s0 = (i << 27) | (n << 24);
return;
}
/*
* If this isn't an escape sequence, it must be part of a
* character. One possibility is that it's a control character
* (00-20 or 7F-9F; also in non-8-bit ISO 2022 subsets I'm
* going to treat all top-half characters as controls), in
* which case we output it verbatim.
*/
if (input_chr < 0x21 ||
(input_chr > 0x7E && (!iso->eightbit || input_chr < 0xA0))) {
/*
* We might be in mid-multibyte-character. If so, clear the
* character state and emit an error token for the
* incomplete character.
*/
if (state->s1 & 0x0F000000) {
state->s1 &= ~0x0F000000;
state->s0 &= 0xFF000000;
emit(emitctx, ERROR);
/*
* If we were in the SS2 or SS3 container, we
* automatically exit it.
*/
if (state->s1 & 0x60000000)
state->s1 &= 0x9FFFFFFF;
}
emit(emitctx, input_chr);
return;
}
/*
* Otherwise, accumulate character data.
*/
{
unsigned long chr;
int chrlen, cont, subcharset, bytes;
/*
* Verify that we've seen the right kind of character for
* what we're currently doing. This only matters in 8-bit
* subsets.
*/
if (iso->eightbit) {
cont = (state->s1 >> 28) & 7;
/*
* If cont==0, we're entitled to see either GL or GR
* characters. If cont==2, we expect only GR; otherwise
* we expect only GL.
*
* If we see a GR character while cont==0, we set
* cont=2 immediately.
*/
if ((cont == 2 && !(input_chr & 0x80)) ||
(cont != 0 && cont != 2 && (input_chr & 0x80))) {
/*
* Clear the previous character; it was prematurely
* terminated by this error.
*/
state->s1 &= ~0x0F000000;
state->s0 &= 0xFF000000;
emit(emitctx, ERROR);
/*
* If we were in the SS2 or SS3 container, we
* automatically exit it.
*/
if (state->s1 & 0x60000000)
state->s1 &= 0x9FFFFFFF;
}
if (cont == 0 && (input_chr & 0x80)) {
state->s1 |= 0x20000000;
}
}
/* The current character and its length. */
chr = ((state->s0 & 0x00FFFFFF) << 8) | (input_chr & 0x7F);
chrlen = ((state->s1 >> 24) & 0xF) + 1;
/* The current sub-charset. */
cont = (state->s1 >> 28) & 7;
if (cont > 1) cont >>= 1;
subcharset = (state->s1 >> (6*cont)) & 0x3F;
/* The number of bytes-per-character in that sub-charset. */
bytes = iso->nbytes[subcharset];
/*
* If this character is now complete, we convert and emit
* it. Otherwise, we simply update the state and return.
*/
if (chrlen >= bytes) {
emit(emitctx, iso->to_ucs(subcharset, chr));
chr = chrlen = 0;
/*
* If we were in the SS2 or SS3 container, we
* automatically exit it.
*/
if (state->s1 & 0x60000000)
state->s1 &= 0x9FFFFFFF;
}
state->s0 = (state->s0 & 0xFF000000) | chr;
state->s1 = (state->s1 & 0xF0FFFFFF) | (chrlen << 24);
}
}
static int write_iso2022s(charset_spec const *charset, long int input_chr,
charset_state *state,
void (*emit)(void *ctx, long int output),
void *emitctx)
{
struct iso2022 const *iso = (struct iso2022 *)charset->data;
int subcharset, len, i, j, cont, topbit = 0;
unsigned long bytes;
/*
* For output, our s1 state variable contains most of the same
* stuff as it did for input - initial-state indicator bit,
* current container, and current subcharset selected in each
* container.
*/
/*
* Analyse the character and find out what subcharset it needs
* to go in.
*/
if (input_chr >= 0 && !iso->from_ucs(input_chr, &subcharset, &bytes))
return FALSE;
if (!(state->s1 & 0x80000000)) {
state->s1 = iso->s1;
if (iso->initial_sequence)
for (i = 0; iso->initial_sequence[i]; i++)
emit(emitctx, iso->initial_sequence[i]);
}
if (input_chr == -1) {
unsigned long oldstate;
int k;
/*
* Special case: reset encoding state.
*/
for (i = 0; iso->reset[i]; i++) {
j = iso->reset[i] - 1;
oldstate = state->s1;
state->s1 &= iso->escapes[j].andbits;
state->s1 ^= iso->escapes[j].xorbits;
if (state->s1 != oldstate) {
/* We must actually emit this sequence. */
for (k = 0; iso->escapes[j].sequence[k]; k++)
emit(emitctx, iso->escapes[j].sequence[k]);
}
}
return TRUE;
}
/*
* Now begins the fun. We now know what subcharset we want. So
* we must find out which container we should select it into,
* select it into it if necessary, select that _container_ if
* necessary, and then output the given bytes.
*/
for (i = 0; i < iso->nescapes; i++)
if (iso->escapes[i].subcharset == subcharset &&
!(iso->escapes[i].container & RO))
break;
assert(i < iso->nescapes);
/*
* We've found the escape sequence which would select this
* subcharset into a container. However, that subcharset might
* already _be_ selected in that container! Check before we go
* to the effort of emitting the sequence.
*/
cont = iso->escapes[i].container &~ RO;
if (((state->s1 >> (6*cont)) & 0x3F) != (unsigned)subcharset) {
for (j = 0; iso->escapes[i].sequence[j]; j++)
emit(emitctx, iso->escapes[i].sequence[j]);
state->s1 &= iso->escapes[i].andbits;
state->s1 ^= iso->escapes[i].xorbits;
}
/*
* Now we know what container our subcharset is in, so we want
* to select that container.
*/
if (cont > 1) {
/* SS2 or SS3; just output the sequence and be done. */
emit(emitctx, ESC);
emit(emitctx, 'L' + cont); /* comes out to 'N' or 'O' */
} else {
/*
* Emit SI or SO, but only if the current container isn't already
* the right one.
*
* Also, in an 8-bit subset, we need not do this; we'll
* just use 8-bit characters to output SO-container
* characters.
*/
if (iso->eightbit && cont == 1 && ((state->s1 >> 28) & 7) == 0) {
topbit = 0x80;
} else if (((state->s1 >> 28) & 7) != (unsigned)cont) {
emit(emitctx, cont ? SO : SI);
state->s1 = (state->s1 & 0x8FFFFFFF) | (cont << 28);
}
}
/*
* We're done. Subcharset is selected in container, container
* is selected. All we need now is to write out the bytes.
*/
len = iso->nbytes[subcharset];
while (len--)
emit(emitctx, ((bytes >> (8*len)) & 0xFF) | topbit);
return TRUE;
}
/*
* ISO-2022-JP, defined in RFC 1468.
*/
static long int iso2022jp_to_ucs(int subcharset, unsigned long bytes)
{
switch (subcharset) {
case 1: /* JIS X 0201 bottom half */
if (bytes == 0x5C)
return 0xA5;
else if (bytes == 0x7E)
return 0x203E;
/* else fall through to ASCII */
case 0: return bytes; /* one-byte ASCII */
/* (no break needed since all control paths have returned) */
case 2: return jisx0208_to_unicode(((bytes >> 8) & 0xFF) - 0x21,
((bytes ) & 0xFF) - 0x21);
default: return ERROR;
}
}
static int iso2022jp_from_ucs(long int ucs, int *subcharset,
unsigned long *bytes)
{
int r, c;
if (ucs < 0x80) {
*subcharset = 0;
*bytes = ucs;
return 1;
} else if (ucs == 0xA5 || ucs == 0x203E) {
*subcharset = 1;
*bytes = (ucs == 0xA5 ? 0x5C : 0x7E);
return 1;
} else if (unicode_to_jisx0208(ucs, &r, &c)) {
*subcharset = 2;
*bytes = ((r+0x21) << 8) | (c+0x21);
return 1;
} else {
return 0;
}
}
static const struct iso2022_escape iso2022jp_escapes[] = {
{"\033$@", 0xFFFFFFC0, 0x00000002, -1, -1}, /* we ignore this one */
{"\033$B", 0xFFFFFFC0, 0x00000002, 0, 2},
{"\033(B", 0xFFFFFFC0, 0x00000000, 0, 0},
{"\033(J", 0xFFFFFFC0, 0x00000001, 0, 1},
};
static const struct iso2022 iso2022jp = {
iso2022jp_escapes, lenof(iso2022jp_escapes),
"\1\1\2", "\3", 0x80000000, NULL, FALSE,
iso2022jp_to_ucs, iso2022jp_from_ucs
};
const charset_spec charset_CS_ISO2022_JP = {
CS_ISO2022_JP, read_iso2022s, write_iso2022s, &iso2022jp
};
/*
* ISO-2022-KR, defined in RFC 1557.
*/
static long int iso2022kr_to_ucs(int subcharset, unsigned long bytes)
{
switch (subcharset) {
case 0: return bytes; /* one-byte ASCII */
case 1: return ksx1001_to_unicode(((bytes >> 8) & 0xFF) - 0x21,
((bytes ) & 0xFF) - 0x21);
default: return ERROR;
}
}
static int iso2022kr_from_ucs(long int ucs, int *subcharset,
unsigned long *bytes)
{
int r, c;
if (ucs < 0x80) {
*subcharset = 0;
*bytes = ucs;
return 1;
} else if (unicode_to_ksx1001(ucs, &r, &c)) {
*subcharset = 1;
*bytes = ((r+0x21) << 8) | (c+0x21);
return 1;
} else {
return 0;
}
}
static const struct iso2022_escape iso2022kr_escapes[] = {
{"\016", 0x8FFFFFFF, 0x10000000, -1, -1},
{"\017", 0x8FFFFFFF, 0x00000000, 0, 0},
{"\033$)C", 0xFFFFF03F, 0x00000040, 1, 1}, /* bits[11:6] <- 1 */
};
static const struct iso2022 iso2022kr = {
iso2022kr_escapes, lenof(iso2022kr_escapes),
"\1\2", "\2", 0x80000040, "\033$)C", FALSE,
iso2022kr_to_ucs, iso2022kr_from_ucs
};
const charset_spec charset_CS_ISO2022_KR = {
CS_ISO2022_KR, read_iso2022s, write_iso2022s, &iso2022kr
};
#else /* ENUM_CHARSETS */
ENUM_CHARSET(CS_ISO2022_JP)
ENUM_CHARSET(CS_ISO2022_KR)
#endif /* ENUM_CHARSETS */