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1/* table.c - Table handling opcodes
2 * Copyright (c) 1995-1997 Stefan Jokisch
3 *
4 * This file is part of Frotz.
5 *
6 * Frotz is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License as published by
8 * the Free Software Foundation; either version 2 of the License, or
9 * (at your option) any later version.
10 *
11 * Frotz is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 * GNU General Public License for more details.
15 *
16 * You should have received a copy of the GNU General Public License
17 * along with this program; if not, write to the Free Software
18 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
19 */
20
21#include "frotz.h"
22
23/*
24 * z_copy_table, copy a table or fill it with zeroes.
25 *
26 * zargs[0] = address of table
27 * zargs[1] = destination address or 0 for fill
28 * zargs[2] = size of table
29 *
30 * Note: Copying is safe even when source and destination overlap; but
31 * if zargs[1] is negative the table _must_ be copied forwards.
32 *
33 */
34
35void z_copy_table (void)
36{
37 zword addr;
38 zword size = zargs[2];
39 zbyte value;
40 int i;
41
42 if (zargs[1] == 0) /* zero table */
43
44 for (i = 0; i < size; i++)
45 storeb ((zword) (zargs[0] + i), 0);
46
47 else if ((short) size < 0 || zargs[0] > zargs[1]) /* copy forwards */
48
49 for (i = 0; i < (((short) size < 0) ? - (short) size : size); i++) {
50 addr = zargs[0] + i;
51 LOW_BYTE (addr, value)
52 storeb ((zword) (zargs[1] + i), value);
53 }
54
55 else /* copy backwards */
56
57 for (i = size - 1; i >= 0; i--) {
58 addr = zargs[0] + i;
59 LOW_BYTE (addr, value)
60 storeb ((zword) (zargs[1] + i), value);
61 }
62
63}/* z_copy_table */
64
65/*
66 * z_loadb, store a value from a table of bytes.
67 *
68 * zargs[0] = address of table
69 * zargs[1] = index of table entry to store
70 *
71 */
72
73void z_loadb (void)
74{
75 zword addr = zargs[0] + zargs[1];
76 zbyte value;
77
78 LOW_BYTE (addr, value)
79
80 store (value);
81
82}/* z_loadb */
83
84/*
85 * z_loadw, store a value from a table of words.
86 *
87 * zargs[0] = address of table
88 * zargs[1] = index of table entry to store
89 *
90 */
91
92void z_loadw (void)
93{
94 zword addr = zargs[0] + 2 * zargs[1];
95 zword value;
96
97 LOW_WORD (addr, value)
98
99 store (value);
100
101}/* z_loadw */
102
103/*
104 * z_scan_table, find and store the address of a target within a table.
105 *
106 * zargs[0] = target value to be searched for
107 * zargs[1] = address of table
108 * zargs[2] = number of table entries to check value against
109 * zargs[3] = type of table (optional, defaults to 0x82)
110 *
111 * Note: The table is a word array if bit 7 of zargs[3] is set; otherwise
112 * it's a byte array. The lower bits hold the address step.
113 *
114 */
115
116void z_scan_table (void)
117{
118 zword addr = zargs[1];
119 int i;
120
121 /* Supply default arguments */
122
123 if (zargc < 4)
124 zargs[3] = 0x82;
125
126 /* Scan byte or word array */
127
128 for (i = 0; i < zargs[2]; i++) {
129
130 if (zargs[3] & 0x80) { /* scan word array */
131
132 zword wvalue;
133
134 LOW_WORD (addr, wvalue)
135
136 if (wvalue == zargs[0])
137 goto finished;
138
139 } else { /* scan byte array */
140
141 zbyte bvalue;
142
143 LOW_BYTE (addr, bvalue)
144
145 if (bvalue == zargs[0])
146 goto finished;
147
148 }
149
150 addr += zargs[3] & 0x7f;
151
152 }
153
154 addr = 0;
155
156finished:
157
158 store (addr);
159 branch (addr);
160
161}/* z_scan_table */
162
163/*
164 * z_storeb, write a byte into a table of bytes.
165 *
166 * zargs[0] = address of table
167 * zargs[1] = index of table entry
168 * zargs[2] = value to be written
169 *
170 */
171
172void z_storeb (void)
173{
174
175 storeb ((zword) (zargs[0] + zargs[1]), zargs[2]);
176
177}/* z_storeb */
178
179/*
180 * z_storew, write a word into a table of words.
181 *
182 * zargs[0] = address of table
183 * zargs[1] = index of table entry
184 * zargs[2] = value to be written
185 *
186 */
187
188void z_storew (void)
189{
190
191 storew ((zword) (zargs[0] + 2 * zargs[1]), zargs[2]);
192
193}/* z_storew */