--- /dev/null
+/*-
+ * Copyright 2009-2012 Chris Spiegel.
+ *
+ * This file is part of Bocfel.
+ *
+ * Bocfel is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License, version
+ * 2 or 3, as published by the Free Software Foundation.
+ *
+ * Bocfel 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 Bocfel. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <stdlib.h>
+#include <stdio.h>
+#include <stdint.h>
+#include <string.h>
+
+#include "dict.h"
+#include "memory.h"
+#include "process.h"
+#include "unicode.h"
+#include "util.h"
+#include "zterp.h"
+
+static uint16_t separators;
+static uint8_t num_separators;
+
+static uint16_t GET_WORD(uint8_t *base)
+{
+ return (base[0] << 8) | base[1];
+}
+static void MAKE_WORD(uint8_t *base, uint16_t val)
+{
+ base[0] = val >> 8;
+ base[1] = val & 0xff;
+}
+
+/* Add the character c to the nth position of the encoded text. c is a
+ * 5-bit value (either a shift character, which selects an alphabet, or
+ * the index into the current alphabet).
+ */
+static void add_zchar(int c, int n, uint8_t *encoded)
+{
+ uint16_t w = GET_WORD(&encoded[2 * (n / 3)]);
+
+ /* From §3.2:
+ * --first byte------- --second byte---
+ * 7 6 5 4 3 2 1 0 7 6 5 4 3 2 1 0
+ * bit --first-- --second--- --third--
+ *
+ * So to figure out which third of the word to store to:
+ * If n is 0, 3, 6, ... then store to the first (left shift 10).
+ * If n is 1, 4, 7, ... then store to the second (left shift 5).
+ * If n is 2, 5, 8, ... then store to the third (left shift 0).
+ * “Or” into the previous value because, unless this is the first
+ * character, there are already values we’ve stored there.
+ */
+ w |= (c & 0x1f) << (5 * (2 - (n % 3)));
+
+ MAKE_WORD(&encoded[2 * (n / 3)], w);
+}
+
+/* Encode the text at “s”, of length “len” (there is not necessarily a
+ * terminating null character) into the buffer “encoded”.
+ *
+ * For V3 the encoded text is 6 Z-characters (4 bytes); for V4 and above
+ * it’s 9 characters (6 bytes). Due to the nature of the loop here,
+ * it’s possible to encode too many bytes. For example, if the string
+ * given is "aaa<" in a V3 game, the three 'a' characters will take up a
+ * word (all three being packed into one), but the single '<' character
+ * will take up two words (one full word and a third of the next) due to
+ * the fact that '<' is not in the alphabet table. Thus the encoded
+ * text will be 7 characters. This is OK because routines that use the
+ * encoded string are smart enough to only pay attention to the first 6
+ * or 9 Z-characters; and partial Z-characters are OK per §3.6.1.
+ *
+ * 1.1 of the standard revises the encoding for V1 and V2 games. I am
+ * not implementing the new rules for two basic reasons:
+ * 1) It apparently only affects three (unnecessary) dictionary words in
+ * the known V1-2 games.
+ * 2) Because of 1, it is not worth the effort to peek ahead and see
+ * what the next character is to determine whether to shift once or
+ * to lock.
+ *
+ * Z-character 0 is a space (§3.5.1), so theoretically a space should be
+ * encoded simply with a zero. However, Inform 6.32 encodes space
+ * (which has the value 32) as a 10-bit ZSCII code, which is the
+ * Z-characters 5, 6, 1, 0. Assume this is correct.
+ */
+static void encode_string(const uint8_t *s, size_t len, uint8_t encoded[8])
+{
+ int n = 0;
+ const int res = zversion <= 3 ? 6 : 9;
+ const int shiftbase = zversion <= 2 ? 1 : 3;
+
+ memset(encoded, 0, 8);
+
+ for(size_t i = 0; i < len && n < res; i++)
+ {
+ int pos;
+
+ pos = atable_pos[s[i]];
+ if(pos >= 0)
+ {
+ int shift = pos / 26;
+ int c = pos % 26;
+
+ if(shift) add_zchar(shiftbase + shift, n++, encoded);
+ add_zchar(c + 6, n++, encoded);
+ }
+ else
+ {
+ add_zchar(shiftbase + 2, n++, encoded);
+ add_zchar(6, n++, encoded);
+ add_zchar(s[i] >> 5, n++, encoded);
+ add_zchar(s[i] & 0x1f, n++, encoded);
+ }
+ }
+
+ while(n < res)
+ {
+ add_zchar(5, n++, encoded);
+ }
+
+ /* §3.2: the MSB of the last encoded word must be set. */
+ if(zversion <= 3) encoded[2] |= 0x80;
+ else encoded[4] |= 0x80;
+}
+
+static int dict_compar(const void *a, const void *b)
+{
+ return memcmp(a, b, zversion <= 3 ? 4 : 6);
+}
+static uint16_t dict_find(const uint8_t *token, size_t len, uint16_t dictionary)
+{
+ uint8_t elength;
+ uint16_t base;
+ long nentries;
+ uint8_t *ret = NULL;
+ uint8_t encoded[8];
+
+ encode_string(token, len, encoded);
+
+ elength = user_byte(dictionary + num_separators + 1);
+ nentries = (int16_t)user_word(dictionary + num_separators + 2);
+ base = dictionary + num_separators + 2 + 2;
+
+ ZASSERT(elength >= (zversion <= 3 ? 4 : 6), "dictionary entry length (%d) too small", elength);
+ ZASSERT(base + (labs(nentries) * elength) < memory_size, "reported dictionary length extends beyond memory size");
+
+ if(nentries > 0)
+ {
+ ret = bsearch(encoded, &memory[base], nentries, elength, dict_compar);
+ }
+ else
+ {
+ for(long i = 0; i < -nentries; i++)
+ {
+ uint8_t *entry = &memory[base + (i * elength)];
+
+ if(dict_compar(encoded, entry) == 0)
+ {
+ ret = entry;
+ break;
+ }
+ }
+ }
+
+ if(ret == NULL) return 0;
+
+ return base + (ret - &memory[base]);
+}
+
+static int is_sep(uint8_t c)
+{
+ if(c == ZSCII_SPACE) return 1;
+
+ for(uint16_t i = 0; i < num_separators; i++) if(user_byte(separators + i) == c) return 1;
+
+ return 0;
+}
+
+static void handle_token(const uint8_t *base, const uint8_t *token, int len, uint16_t parse, uint16_t dictionary, int found, int flag)
+{
+ uint16_t d;
+ const uint8_t examine[] = { 'e', 'x', 'a', 'm', 'i', 'n', 'e' };
+ const uint8_t again[] = { 'a', 'g', 'a', 'i', 'n' };
+ const uint8_t wait[] = { 'w', 'a', 'i', 't' };
+
+ d = dict_find(token, len, dictionary);
+
+ if(!options.disable_abbreviations && base == token && len == 1)
+ {
+ if (*token == 'x') d = dict_find(examine, sizeof examine, dictionary);
+ else if(*token == 'g') d = dict_find(again, sizeof again, dictionary);
+ else if(*token == 'z') d = dict_find(wait, sizeof wait, dictionary);
+ }
+
+ if(flag && d == 0) return;
+
+ parse = parse + 2 + (found * 4);
+
+ user_store_word(parse, d);
+
+ user_store_byte(parse + 2, len);
+
+ if(zversion <= 4) user_store_byte(parse + 3, token - base + 1);
+ else user_store_byte(parse + 3, token - base + 2);
+}
+
+/* The behavior of tokenize is described in §15 (under the read opcode)
+ * and §13.
+ *
+ * For the text buffer, byte 0 is ignored in both V3/4 and V5+.
+ * Byte 1 of V3/4 is the start of the string, while in V5+ it is the
+ * length of the string.
+ * Byte 2 of V5+ is the start of the string. V3/4 strings have a null
+ * terminator, while V5+ do not.
+ *
+ * For the parse buffer, byte 0 contains the maximum number of tokens
+ * that can be read.
+ * The number of tokens found is stored in byte 1.
+ * Each token is then represented by a 4-byte chunk with the following
+ * information:
+ * • The first two bytes are the byte address of the dictionary entry
+ * for the token, or 0 if the token was not found in the dictionary.
+ * • The next byte is the length of the token.
+ * • The final byte is the offset in the string of the token.
+ */
+void tokenize(uint16_t text, uint16_t parse, uint16_t dictionary, int flag)
+{
+ const uint8_t *p, *lastp;
+ uint8_t *string;
+ uint32_t text_len = 0;
+ const int maxwords = user_byte(parse);
+ int in_word = 0;
+ int found = 0;
+
+ if(dictionary == 0) dictionary = header.dictionary;
+
+ ZASSERT(dictionary != 0, "attempt to tokenize without a valid dictionary");
+
+ num_separators = user_byte(dictionary);
+ separators = dictionary + 1;
+
+ if(zversion >= 5) text_len = user_byte(text + 1);
+ else while(user_byte(text + 1 + text_len) != 0) text_len++;
+
+ ZASSERT(text + 1 + (zversion >= 5) + text_len < memory_size, "attempt to tokenize out-of-bounds string");
+
+ string = &memory[text + 1 + (zversion >= 5)];
+
+ for(p = string; p - string < text_len && *p == ZSCII_SPACE; p++);
+ lastp = p;
+
+ text_len -= (p - string);
+
+ do
+ {
+ if(!in_word && text_len != 0 && !is_sep(*p))
+ {
+ in_word = 1;
+ lastp = p;
+ }
+
+ if(text_len == 0 || is_sep(*p))
+ {
+ if(in_word)
+ {
+ handle_token(string, lastp, p - lastp, parse, dictionary, found++, flag);
+ }
+
+ /* §13.6.1: Separators (apart from a space) are tokens too. */
+ if(text_len != 0 && *p != ZSCII_SPACE)
+ {
+ handle_token(string, p, 1, parse, dictionary, found++, flag);
+ }
+
+ if(found == maxwords) break;
+
+ in_word = 0;
+ }
+
+ p++;
+
+ } while(text_len--);
+
+ user_store_byte(parse + 1, found);
+}
+
+static void encode_text(uint32_t text, uint16_t len, uint16_t coded)
+{
+ uint8_t encoded[8];
+
+ ZASSERT(text + len < memory_size, "reported text length extends beyond memory size");
+
+ encode_string(&memory[text], len, encoded);
+
+ for(int i = 0; i < 6; i++) user_store_byte(coded + i, encoded[i]);
+}
+
+void ztokenise(void)
+{
+ if(znargs < 3) zargs[2] = 0;
+ if(znargs < 4) zargs[3] = 0;
+
+ tokenize(zargs[0], zargs[1], zargs[2], zargs[3]);
+}
+
+void zencode_text(void)
+{
+ encode_text(zargs[0] + zargs[2], zargs[1], zargs[3]);
+}
projects / projects / chimara / chimara.git / blobdiff