apps/plugins/frotz/math.c

   1 /* math.c - Arithmetic, compare and logical 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_add, 16bit addition.
  25  *
  26  *      zargs[0] = first value
  27  *      zargs[1] = second value
  28  *
  29  */
  30
  31 void z_add (void)
  32 {
  33
  34     store ((zword) ((short) zargs[0] + (short) zargs[1]));
  35
  36 }/* z_add */
  37
  38 /*
  39  * z_and, bitwise AND operation.
  40  *
  41  *      zargs[0] = first value
  42  *      zargs[1] = second value
  43  *
  44  */
  45
  46 void z_and (void)
  47 {
  48
  49     store ((zword) (zargs[0] & zargs[1]));
  50
  51 }/* z_and */
  52
  53 /*
  54  * z_art_shift, arithmetic SHIFT operation.
  55  *
  56  *      zargs[0] = value
  57  *      zargs[1] = #positions to shift left (positive) or right
  58  *
  59  */
  60
  61 void z_art_shift (void)
  62 {
  63
  64     if ((short) zargs[1] > 0)
  65         store ((zword) ((short) zargs[0] << (short) zargs[1]));
  66     else
  67         store ((zword) ((short) zargs[0] >> - (short) zargs[1]));
  68
  69 }/* z_art_shift */
  70
  71 /*
  72  * z_div, signed 16bit division.
  73  *
  74  *      zargs[0] = first value
  75  *      zargs[1] = second value
  76  *
  77  */
  78
  79 void z_div (void)
  80 {
  81
  82     if (zargs[1] == 0)
  83         runtime_error (ERR_DIV_ZERO);
  84
  85     store ((zword) ((short) zargs[0] / (short) zargs[1]));
  86
  87 }/* z_div */
  88
  89 /*
  90  * z_je, branch if the first value equals any of the following.
  91  *
  92  *      zargs[0] = first value
  93  *      zargs[1] = second value (optional)
  94  *      ...
  95  *      zargs[3] = fourth value (optional)
  96  *
  97  */
  98
  99 void z_je (void)
 100 {
 101
 102     branch (
 103         zargc > 1 && (zargs[0] == zargs[1] || (
 104         zargc > 2 && (zargs[0] == zargs[2] || (
 105         zargc > 3 && (zargs[0] == zargs[3]))))));
 106
 107 }/* z_je */
 108
 109 /*
 110  * z_jg, branch if the first value is greater than the second.
 111  *
 112  *      zargs[0] = first value
 113  *      zargs[1] = second value
 114  *
 115  */
 116
 117 void z_jg (void)
 118 {
 119
 120     branch ((short) zargs[0] > (short) zargs[1]);
 121
 122 }/* z_jg */
 123
 124 /*
 125  * z_jl, branch if the first value is less than the second.
 126  *
 127  *      zargs[0] = first value
 128  *      zargs[1] = second value
 129  *
 130  */
 131
 132 void z_jl (void)
 133 {
 134
 135     branch ((short) zargs[0] < (short) zargs[1]);
 136
 137 }/* z_jl */
 138
 139 /*
 140  * z_jz, branch if value is zero.
 141  *
 142  *      zargs[0] = value
 143  *
 144  */
 145
 146 void z_jz (void)
 147 {
 148
 149     branch ((short) zargs[0] == 0);
 150
 151 }/* z_jz */
 152
 153 /*
 154  * z_log_shift, logical SHIFT operation.
 155  *
 156  *      zargs[0] = value
 157  *      zargs[1] = #positions to shift left (positive) or right (negative)
 158  *
 159  */
 160
 161 void z_log_shift (void)
 162 {
 163
 164     if ((short) zargs[1] > 0)
 165         store ((zword) (zargs[0] << (short) zargs[1]));
 166     else
 167         store ((zword) (zargs[0] >> - (short) zargs[1]));
 168
 169 }/* z_log_shift */
 170
 171 /*
 172  * z_mod, remainder after signed 16bit division.
 173  *
 174  *      zargs[0] = first value
 175  *      zargs[1] = second value
 176  *
 177  */
 178
 179 void z_mod (void)
 180 {
 181
 182     if (zargs[1] == 0)
 183         runtime_error (ERR_DIV_ZERO);
 184
 185     store ((zword) ((short) zargs[0] % (short) zargs[1]));
 186
 187 }/* z_mod */
 188
 189 /*
 190  * z_mul, 16bit multiplication.
 191  *
 192  *      zargs[0] = first value
 193  *      zargs[1] = second value
 194  *
 195  */
 196
 197 void z_mul (void)
 198 {
 199
 200     store ((zword) ((short) zargs[0] * (short) zargs[1]));
 201
 202 }/* z_mul */
 203
 204 /*
 205  * z_not, bitwise NOT operation.
 206  *
 207  *      zargs[0] = value
 208  *
 209  */
 210
 211 void z_not (void)
 212 {
 213
 214     store ((zword) ~zargs[0]);
 215
 216 }/* z_not */
 217
 218 /*
 219  * z_or, bitwise OR operation.
 220  *
 221  *      zargs[0] = first value
 222  *      zargs[1] = second value
 223  *
 224  */
 225
 226 void z_or (void)
 227 {
 228
 229     store ((zword) (zargs[0] | zargs[1]));
 230
 231 }/* z_or */
 232
 233 /*
 234  * z_sub, 16bit substraction.
 235  *
 236  *      zargs[0] = first value
 237  *      zargs[1] = second value
 238  *
 239  */
 240
 241 void z_sub (void)
 242 {
 243
 244     store ((zword) ((short) zargs[0] - (short) zargs[1]));
 245
 246 }/* z_sub */
 247
 248 /*
 249  * z_test, branch if all the flags of a bit mask are set in a value.
 250  *
 251  *      zargs[0] = value to be examined
 252  *      zargs[1] = bit mask
 253  *
 254  */
 255
 256 void z_test (void)
 257 {
 258
 259     branch ((zargs[0] & zargs[1]) == zargs[1]);
 260
 261 }/* z_test */