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engines/glk/tads/tads2/character_map.cpp

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+/* ScummVM - Graphic Adventure Engine
+ *
+ * ScummVM is the legal property of its developers, whose names
+ * are too numerous to list here. Please refer to the COPYRIGHT
+ * file distributed with this source distribution.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#include "glk/tads/tads2/character_map.h"
+#include "glk/tads/tads2/lib.h"
+#include "glk/tads/tads2/error.h"
+#include "glk/tads/tads2/os.h"
+#include "glk/tads/tads2/text_io.h"
+#include "glk/tads/os_frob_tads.h"
+#include "glk/tads/os_glk.h"
+#include "common/algorithm.h"
+
+namespace Glk {
+namespace TADS {
+namespace TADS2 {
+
+/* ------------------------------------------------------------------------ */
+/*
+ *   Global variables for character mapping tables
+ */
+
+unsigned char G_cmap_input[256];
+unsigned char G_cmap_output[256];
+char G_cmap_id[5];
+char G_cmap_ldesc[CMAP_LDESC_MAX_LEN + 1];
+
+
+/*
+ *   static variables
+ */
+
+/*
+ *   flag: true -> a character set has been explicitly loaded, so we
+ *   should ignore any game character set setting
+ */
+static int S_cmap_loaded;
+
+
+/* ------------------------------------------------------------------------ */
+/*
+ *   Initialize the default character mappings
+ */
+void cmap_init_default(void)
+{
+	size_t i;
+
+	/* initialize the input table */
+	for (i = 0 ; i < sizeof(G_cmap_input)/sizeof(G_cmap_input[0]) ; ++i)
+		G_cmap_input[i] = (unsigned char)i;
+
+	/* initialize the output table */
+	for (i = 0 ; i < sizeof(G_cmap_output)/sizeof(G_cmap_output[0]) ; ++i)
+		G_cmap_output[i] = (unsigned char)i;
+
+	/* we have a null ID */
+	memset(G_cmap_id, 0, sizeof(G_cmap_id));
+
+	/* indicate that it's the default */
+	Common::strcpy_s(G_cmap_ldesc, "(native/no mapping)");
+
+	/* note that we have no character set loaded */
+	S_cmap_loaded = FALSE;
+}
+
+/* ------------------------------------------------------------------------ */
+/*
+ *   Internal routine to load a character map from a file
+ */
+static int cmap_load_internal(char *filename)
+{
+	osfildef *fp;
+	static char sig1[] = CMAP_SIG_S100;
+	char buf[256];
+	uchar lenbuf[2];
+	size_t len;
+	int sysblk;
+
+	/* if there's no mapping file, use the default mapping */
+	if (filename == nullptr)
+	{
+		/* initialize with the default mapping */
+		cmap_init_default();
+
+		/* return success */
+		return 0;
+	}
+
+	/* open the file */
+	fp = osfoprb(filename, OSFTCMAP);
+	if (fp == nullptr)
+		return 1;
+
+	/* check the signature */
+	if (osfrb(fp, buf, sizeof(sig1))
+		|| memcmp(buf, sig1, sizeof(sig1)) != 0)
+	{
+		osfcls(fp);
+		return 2;
+	}
+
+	/* load the ID */
+	G_cmap_id[4] = '\0';
+	if (osfrb(fp, G_cmap_id, 4))
+	{
+		osfcls(fp);
+		return 3;
+	}
+
+	/* load the long description */
+	if (osfrb(fp, lenbuf, 2)
+		|| (len = osrp2(lenbuf)) > sizeof(G_cmap_ldesc)
+		|| osfrb(fp, G_cmap_ldesc, len))
+	{
+		osfcls(fp);
+		return 4;
+	}
+
+	/* load the two tables - input, then output */
+	if (osfrb(fp, G_cmap_input, sizeof(G_cmap_input))
+		|| osfrb(fp, G_cmap_output, sizeof(G_cmap_output)))
+	{
+		osfcls(fp);
+		return 5;
+	}
+
+	/* read the next section header */
+	if (osfrb(fp, buf, 4))
+	{
+		osfcls(fp);
+		return 6;
+	}
+
+	/* if it's "SYSI", read the system information string */
+	if (!memcmp(buf, "SYSI", 4))
+	{
+		/* read the length prefix, then the string */
+		if (osfrb(fp, lenbuf, 2)
+			|| (len = osrp2(lenbuf)) > sizeof(buf)
+			|| osfrb(fp, buf, len))
+		{
+			osfcls(fp);
+			return 7;
+		}
+
+		/* we have a system information block */
+		sysblk = TRUE;
+	}
+	else
+	{
+		/* there's no system information block */
+		sysblk = FALSE;
+	}
+
+	/*
+	 *   call the OS code, so that it can do any system-dependent
+	 *   initialization for the new character mapping
+	 */
+	os_advise_load_charmap(G_cmap_id, G_cmap_ldesc, sysblk ? buf : "");
+
+	/* read the next section header */
+	if (sysblk && osfrb(fp, buf, 4))
+	{
+		osfcls(fp);
+		return 8;
+	}
+
+	/* see if we have an entity list */
+	if (!memcmp(buf, "ENTY", 4))
+	{
+		/* read the entities */
+		for (;;)
+		{
+			size_t blen;
+			unsigned int cval;
+			char expansion[CMAP_MAX_ENTITY_EXPANSION];
+
+			/* read the next item's length and character value */
+			if (osfrb(fp, buf, 4))
+			{
+				osfcls(fp);
+				return 9;
+			}
+
+			/* decode the values */
+			blen = osrp2(buf);
+			cval = osrp2(buf+2);
+
+			/* if we've reached the zero marker, we're done */
+			if (blen == 0 && cval == 0)
+				break;
+
+			/* read the string */
+			if (blen > CMAP_MAX_ENTITY_EXPANSION
+				|| osfrb(fp, expansion, blen))
+			{
+				osfcls(fp);
+				return 10;
+			}
+
+			/* tell the output code about the expansion */
+			tio_set_html_expansion(cval, expansion, blen);
+		}
+	}
+
+	/*
+	 *   ignore anything else we find - if the file format is updated to
+	 *   include extra information in the future, and this old code tries
+	 *   to load an updated file, we'll just ignore the new information,
+	 *   which should always be placed after the "SYSI" block (if present)
+	 *   to ensure compatibility with past versions (such as this code)
+	 */
+
+	/* no problems - close the file and return success */
+	osfcls(fp);
+	return 0;
+}
+
+
+/* ------------------------------------------------------------------------ */
+/*
+ *   Explicitly load a character set from a file.  This character set
+ *   mapping will override any implicit character set mapping that we read
+ *   from a game file.  This should be called when the player explicitly
+ *   loads a character set (via a command line option or similar action).
+ */
+int cmap_load(char *filename)
+{
+	int err;
+
+	/* try loading the file */
+	if ((err = cmap_load_internal(filename)) != 0)
+		return err;
+
+	/*
+	 *   note that we've explicitly loaded a character set, if they named
+	 *   a character set (if not, this simply establishes the default
+	 *   setting, so we haven't explicitly loaded anything)
+	 */
+	if (filename != nullptr)
+		S_cmap_loaded = TRUE;
+
+	/* success */
+	return 0;
+}
+
+
+/* ------------------------------------------------------------------------ */
+/*
+ *   Explicitly override any game character set and use no character set
+ *   instead.
+ */
+void cmap_override(void)
+{
+	/* apply the default mapping */
+	cmap_init_default();
+
+	/*
+	 *   pretend we have a character map loaded, so that we don't try to
+	 *   load another one if the game specifies a character set
+	 */
+	S_cmap_loaded = TRUE;
+}
+
+
+/* ------------------------------------------------------------------------ */
+/*
+ *   Set the game's internal character set.  This is called when a game is
+ *   loaded, and the game specifies a character set.
+ */
+void cmap_set_game_charset(errcxdef *ec,
+						   char *internal_id, char *internal_ldesc,
+						   char *argv0)
+{
+	char filename[OSFNMAX];
+
+	/*
+	 *   If a character set is already explicitly loaded, ignore the
+	 *   game's character set - the player asked us to use a particular
+	 *   mapping, so ignore what the game wants.  (This will probably
+	 *   result in incorrect display of non-ASCII character values, but
+	 *   the player is most likely to use this to avoid errors when an
+	 *   appropriate mapping file for the game is not available.  In this
+	 *   case, the player informs us by setting the option that he or she
+	 *   knows and accepts that the game will not look exactly right.)
+	 */
+	if (S_cmap_loaded)
+		return;
+
+	/*
+	 *   ask the operating system to name the mapping file -- this routine
+	 *   will determine, if possible, the current native character set,
+	 *   and apply a system-specific naming convention to tell us what
+	 *   mapping file we should open
+	 */
+	os_gen_charmap_filename(filename, internal_id, argv0);
+
+	/* try loading the mapping file */
+	if (cmap_load_internal(filename))
+		errsig2(ec, ERR_CHRNOFILE,
+				ERRTSTR, errstr(ec, filename, strlen(filename)),
+				ERRTSTR, errstr(ec, internal_ldesc, strlen(internal_ldesc)));
+
+	/*
+	 *   We were successful - the game's internal character set is now
+	 *   mapped to the current native character set.  Even though we
+	 *   loaded an ldesc from the mapping file, forget that and store the
+	 *   internal ldesc that the game specified.  The reason we do this is
+	 *   that it's possible that the player will dynamically switch native
+	 *   character sets in the future, at which point we'll need to
+	 *   re-load the mapping table, which could raise an error if a
+	 *   mapping file for the new character set isn't available.  So, we
+	 *   may need to provide the same explanation later that we needed to
+	 *   provide here.  Save the game's character set ldesc for that
+	 *   eventuality, since it describes exactly what the *game* wanted.
+	 */
+	Common::strcpy_s(G_cmap_ldesc, internal_ldesc);
+}
+
+} // End of namespace TADS2
+} // End of namespace TADS
+} // End of namespace Glk