terminal.c

大名鼎鼎的远程登录软件putty的Symbian版源码

	hdrsize++;
	if (hdrsize == 128) {
	    b->data[hdrpos] = hdrsize - 1;
	    hdrpos = b->len;
	    hdrsize = 0;
	    add(b, 0);
	    prevlen = prevpos = 0;
	    prev2 = FALSE;
	}
    }

    /*
     * Clean up.
     */
    if (hdrsize > 0) {
	assert(hdrsize <= 128);
	b->data[hdrpos] = hdrsize - 1;
    } else {
	b->len = hdrpos;
    }
}
static void makeliteral_chr(struct buf *b, termchar *c, unsigned long *state)
{
    /*
     * My encoding for characters is UTF-8-like, in that it stores
     * 7-bit ASCII in one byte and uses high-bit-set bytes as
     * introducers to indicate a longer sequence. However, it's
     * unlike UTF-8 in that it doesn't need to be able to
     * resynchronise, and therefore I don't want to waste two bits
     * per byte on having recognisable continuation characters.
     * Also I don't want to rule out the possibility that I may one
     * day use values 0x80000000-0xFFFFFFFF for interesting
     * purposes, so unlike UTF-8 I need a full 32-bit range.
     * Accordingly, here is my encoding:
     * 
     * 00000000-0000007F: 0xxxxxxx (but see below)
     * 00000080-00003FFF: 10xxxxxx xxxxxxxx
     * 00004000-001FFFFF: 110xxxxx xxxxxxxx xxxxxxxx
     * 00200000-0FFFFFFF: 1110xxxx xxxxxxxx xxxxxxxx xxxxxxxx
     * 10000000-FFFFFFFF: 11110ZZZ xxxxxxxx xxxxxxxx xxxxxxxx xxxxxxxx
     * 
     * (`Z' is like `x' but is always going to be zero since the
     * values I'm encoding don't go above 2^32. In principle the
     * five-byte form of the encoding could extend to 2^35, and
     * there could be six-, seven-, eight- and nine-byte forms as
     * well to allow up to 64-bit values to be encoded. But that's
     * completely unnecessary for these purposes!)
     * 
     * The encoding as written above would be very simple, except
     * that 7-bit ASCII can occur in several different ways in the
     * terminal data; sometimes it crops up in the D800 page
     * (CSET_ASCII) but at other times it's in the 0000 page (real
     * Unicode). Therefore, this encoding is actually _stateful_:
     * the one-byte encoding of 00-7F actually indicates `reuse the
     * upper three bytes of the last character', and to encode an
     * absolute value of 00-7F you need to use the two-byte form
     * instead.
     */
    if ((c->chr & ~0x7F) == *state) {
	add(b, (unsigned char)(c->chr & 0x7F));
    } else if (c->chr < 0x4000) {
	add(b, (unsigned char)(((c->chr >> 8) & 0x3F) | 0x80));
	add(b, (unsigned char)(c->chr & 0xFF));
    } else if (c->chr < 0x200000) {
	add(b, (unsigned char)(((c->chr >> 16) & 0x1F) | 0xC0));
	add(b, (unsigned char)((c->chr >> 8) & 0xFF));
	add(b, (unsigned char)(c->chr & 0xFF));
    } else if (c->chr < 0x10000000) {
	add(b, (unsigned char)(((c->chr >> 24) & 0x0F) | 0xE0));
	add(b, (unsigned char)((c->chr >> 16) & 0xFF));
	add(b, (unsigned char)((c->chr >> 8) & 0xFF));
	add(b, (unsigned char)(c->chr & 0xFF));
    } else {
	add(b, 0xF0);
	add(b, (unsigned char)((c->chr >> 24) & 0xFF));
	add(b, (unsigned char)((c->chr >> 16) & 0xFF));
	add(b, (unsigned char)((c->chr >> 8) & 0xFF));
	add(b, (unsigned char)(c->chr & 0xFF));
    }
    *state = c->chr & ~0xFF;
}
static void makeliteral_attr(struct buf *b, termchar *c, unsigned long *state)
{
    /*
     * My encoding for attributes is 16-bit-granular and assumes
     * that the top bit of the word is never required. I either
     * store a two-byte value with the top bit clear (indicating
     * just that value), or a four-byte value with the top bit set
     * (indicating the same value with its top bit clear).
     */
    if (c->attr < 0x8000) {
	add(b, (unsigned char)((c->attr >> 8) & 0xFF));
	add(b, (unsigned char)(c->attr & 0xFF));
    } else {
	add(b, (unsigned char)(((c->attr >> 24) & 0x7F) | 0x80));
	add(b, (unsigned char)((c->attr >> 16) & 0xFF));
	add(b, (unsigned char)((c->attr >> 8) & 0xFF));
	add(b, (unsigned char)(c->attr & 0xFF));
    }
}
static void makeliteral_cc(struct buf *b, termchar *c, unsigned long *state)
{
    /*
     * For combining characters, I just encode a bunch of ordinary
     * chars using makeliteral_chr, and terminate with a \0
     * character (which I know won't come up as a combining char
     * itself).
     * 
     * I don't use the stateful encoding in makeliteral_chr.
     */
    unsigned long zstate;
    termchar z;

    while (c->cc_next) {
	c += c->cc_next;

	assert(c->chr != 0);

	zstate = 0;
	makeliteral_chr(b, c, &zstate);
    }

    z.chr = 0;
    zstate = 0;
    makeliteral_chr(b, &z, &zstate);
}

static termline *decompressline(unsigned char *data, int *bytes_used);

static unsigned char *compressline(termline *ldata)
{
    struct buf buffer = { NULL, 0, 0 }, *b = &buffer;

    /*
     * First, store the column count, 7 bits at a time, least
     * significant `digit' first, with the high bit set on all but
     * the last.
     */
    {
	int n = ldata->cols;
	while (n >= 128) {
	    add(b, (unsigned char)((n & 0x7F) | 0x80));
	    n >>= 7;
	}
	add(b, (unsigned char)(n));
    }

    /*
     * Next store the lattrs; same principle.
     */
    {
	int n = ldata->lattr;
	while (n >= 128) {
	    add(b, (unsigned char)((n & 0x7F) | 0x80));
	    n >>= 7;
	}
	add(b, (unsigned char)(n));
    }

    /*
     * Now we store a sequence of separate run-length encoded
     * fragments, each containing exactly as many symbols as there
     * are columns in the ldata.
     * 
     * All of these have a common basic format:
     * 
     *  - a byte 00-7F indicates that X+1 literals follow it
     * 	- a byte 80-FF indicates that a single literal follows it
     * 	  and expects to be repeated (X-0x80)+2 times.
     * 
     * The format of the `literals' varies between the fragments.
     */
    makerle(b, ldata, makeliteral_chr);
    makerle(b, ldata, makeliteral_attr);
    makerle(b, ldata, makeliteral_cc);

    /*
     * Diagnostics: ensure that the compressed data really does
     * decompress to the right thing.
     * 
     * XXX-REMOVE-BEFORE-RELEASE: This is a bit performance-heavy
     * to be leaving in production code.
     */
#ifndef CHECK_SB_COMPRESSION
    {
	int dused;
	termline *dcl;
	int i;

#ifdef DIAGNOSTIC_SB_COMPRESSION
	for (i = 0; i < b->len; i++) {
	    printf(" %02x ", b->data[i]);
	}
	printf("\n");
#endif

	dcl = decompressline(b->data, &dused);
	assert(b->len == dused);
	assert(ldata->cols == dcl->cols);
	assert(ldata->lattr == dcl->lattr);
	for (i = 0; i < ldata->cols; i++)
	    assert(termchars_equal(&ldata->chars[i], &dcl->chars[i]));

#ifdef DIAGNOSTIC_SB_COMPRESSION
	printf("%d cols (%d bytes) -> %d bytes (factor of %g)\n",
	       ldata->cols, 4 * ldata->cols, dused,
	       (double)dused / (4 * ldata->cols));
#endif

	freeline(dcl);
    }
#endif

    /*
     * Trim the allocated memory so we don't waste any, and return.
     */
    return sresize(b->data, b->len, unsigned char);
}

static void readrle(struct buf *b, termline *ldata,
		    void (*readliteral)(struct buf *b, termchar *c,
					termline *ldata, unsigned long *state))
{
    int n = 0;
    unsigned long state = 0;

    while (n < ldata->cols) {
	int hdr = get(b);

	if (hdr >= 0x80) {
	    /* A run. */

	    int pos = b->len, count = hdr + 2 - 0x80;
	    while (count--) {
		assert(n < ldata->cols);
		b->len = pos;
		readliteral(b, ldata->chars + n, ldata, &state);
		n++;
	    }
	} else {
	    /* Just a sequence of consecutive literals. */

	    int count = hdr + 1;
	    while (count--) {
		assert(n < ldata->cols);
		readliteral(b, ldata->chars + n, ldata, &state);
		n++;
	    }
	}
    }

    assert(n == ldata->cols);
}
static void readliteral_chr(struct buf *b, termchar *c, termline *ldata,
			    unsigned long *state)
{
    int byte;

    /*
     * 00000000-0000007F: 0xxxxxxx
     * 00000080-00003FFF: 10xxxxxx xxxxxxxx
     * 00004000-001FFFFF: 110xxxxx xxxxxxxx xxxxxxxx
     * 00200000-0FFFFFFF: 1110xxxx xxxxxxxx xxxxxxxx xxxxxxxx
     * 10000000-FFFFFFFF: 11110ZZZ xxxxxxxx xxxxxxxx xxxxxxxx xxxxxxxx
     */

    byte = get(b);
    if (byte < 0x80) {
	c->chr = byte | *state;
    } else if (byte < 0xC0) {
	c->chr = (byte &~ 0xC0) << 8;
	c->chr |= get(b);
    } else if (byte < 0xE0) {
	c->chr = (byte &~ 0xE0) << 16;
	c->chr |= get(b) << 8;
	c->chr |= get(b);
    } else if (byte < 0xF0) {
	c->chr = (byte &~ 0xF0) << 24;
	c->chr |= get(b) << 16;
	c->chr |= get(b) << 8;
	c->chr |= get(b);
    } else {
	assert(byte == 0xF0);
	c->chr = get(b) << 24;
	c->chr |= get(b) << 16;
	c->chr |= get(b) << 8;
	c->chr |= get(b);
    }
    *state = c->chr & ~0xFF;
}
static void readliteral_attr(struct buf *b, termchar *c, termline *ldata,
			     unsigned long *state)
{
    int val;

    val = get(b) << 8;
    val |= get(b);

    if (val >= 0x8000) {
	val <<= 16;
	val |= get(b) << 8;
	val |= get(b);
    }

    c->attr = val;
}
static void readliteral_cc(struct buf *b, termchar *c, termline *ldata,
			   unsigned long *state)
{
    termchar n;
    unsigned long zstate;
    int x = c - ldata->chars;

    c->cc_next = 0;

    while (1) {
	zstate = 0;
	readliteral_chr(b, &n, ldata, &zstate);
	if (!n.chr)
	    break;
	add_cc(ldata, x, n.chr);
    }
}

static termline *decompressline(unsigned char *data, int *bytes_used)
{
    int ncols, byte, shift;
    struct buf buffer, *b = &buffer;
    termline *ldata;

    b->data = data;
    b->len = 0;

    /*
     * First read in the column count.
     */
    ncols = shift = 0;
    do {
	byte = get(b);
	ncols |= (byte & 0x7F) << shift;
	shift += 7;
    } while (byte & 0x80);

    /*
     * Now create the output termline.
     */
    ldata = snew(termline);
    ldata->chars = snewn(ncols, termchar);
    ldata->cols = ldata->size = ncols;
    ldata->temporary = TRUE;
    ldata->cc_free = 0;

    /*
     * We must set all the cc pointers in ldata->chars to 0 right
     * now, so that cc diagnostics that verify the integrity of the
     * whole line will make sense while we're in the middle of
     * building it up.
     */
    {
	int i;
	for (i = 0; i < ldata->cols; i++)
	    ldata->chars[i].cc_next = 0;
    }

    /*
     * Now read in the lattr.
     */
    ldata->lattr = shift = 0;
    do {
	byte = get(b);
	ldata->lattr |= (byte & 0x7F) << shift;
	shift += 7;
    } while (byte & 0x80);

    /*
     * Now we read in each of the RLE streams in turn.
     */
    readrle(b, ldata, readliteral_chr);
    readrle(b, ldata, readliteral_attr);
    readrle(b, ldata, readliteral_cc);

    /* Return the number of bytes read, for diagnostic purposes. */
    if (bytes_used)
	*bytes_used = b->len;

    return ldata;
}

/*
 * Resize a line to make it `cols' columns wide.
 */
static void resizeline(Terminal *term, termline *line, int cols)
{
    int i, oldcols;

    if (line->cols != cols) {

	oldcols = line->cols;

	/*
	 * This line is the wrong length, which probably means it
	 * hasn't been accessed since a resize. Resize it now.
	 * 
	 * First, go through all the characters that will be thrown
	 * out in the resize (if we're shrinking the line) and
	 * return their cc lists to the cc free list.
	 */
	for (i = cols; i < oldcols; i++)
	    clear_cc(line, i);

	/*
	 * If we're shrinking the line, we now bodily move the
	 * entire cc section from where it started to where it now
	 * needs to be. (We have to do this before the resize, so
	 * that the data we're copying is still there. However, if
	 * we're expanding, we have to wait until _after_ the
	 * resize so that the space we're copying into is there.)
	 */
	if (cols < oldcols)
	    memmove(line->chars + cols, line->chars + oldcols,
		    (line->size - line->cols) * TSIZE);

	/*
	 * Now do the actual resize, leaving the _same_ amount of
	 * cc space as there was to begin with.
	 */
	line->size += cols - oldcols;
	line->chars = sresize(line->chars, line->size, TTYPE);
	line->cols = cols;

	/*
	 * If we're expanding the line, _now_ we move the cc
	 * section.
	 */
	if (cols > oldcols)
	    memmove(line->chars + cols, line->chars + oldcols,
		    (line->size - line->cols) * TSIZE);

	/*
	 * Go through what's left of the original line, and adjust
	 * the first cc_next pointer in each list. (All the
	 * subsequent ones are still valid because they are
	 * relative offsets within the cc block.) Also do the same
	 * to the head of the cc_free list.
	 */
	for (i = 0; i < oldcols && i < cols; i++)
	    if (line->chars[i].cc_next)
		line->chars[i].cc_next += cols - oldcols;
	if (line->cc_free)
	    line->cc_free += cols - oldcols;

	/*
	 * And finally fill in the new space with erase chars. (We
	 * don't have to worry about cc lists here, because we
	 * _know_ the erase char doesn't have one.)
	 */
	for (i = oldcols; i < cols; i++)
	    line->chars[i] = term->basic_erase_char;

	cc_check(line);		       /* XXX-REMOVE-BEFORE-RELEASE */
    }
}