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diff --git a/apps/plugins/frotz/process.c b/apps/plugins/frotz/process.c
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+/* process.c - Interpreter loop and program control
+ * Copyright (c) 1995-1997 Stefan Jokisch
+ *
+ * This file is part of Frotz.
+ *
+ * Frotz 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 2 of the License, or
+ * (at your option) any later version.
+ *
+ * Frotz 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, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
+ */
+
+#include "frotz.h"
+
+#ifdef DJGPP
+#include "djfrotz.h"
+#endif
+
+
+zword zargs[8];
+int zargc;
+
+static int finished = 0;
+
+static void __extended__ (void);
+static void __illegal__ (void);
+
+void (*op0_opcodes[0x10]) (void) = {
+ z_rtrue,
+ z_rfalse,
+ z_print,
+ z_print_ret,
+ z_nop,
+ z_save,
+ z_restore,
+ z_restart,
+ z_ret_popped,
+ z_catch,
+ z_quit,
+ z_new_line,
+ z_show_status,
+ z_verify,
+ __extended__,
+ z_piracy
+};
+
+void (*op1_opcodes[0x10]) (void) = {
+ z_jz,
+ z_get_sibling,
+ z_get_child,
+ z_get_parent,
+ z_get_prop_len,
+ z_inc,
+ z_dec,
+ z_print_addr,
+ z_call_s,
+ z_remove_obj,
+ z_print_obj,
+ z_ret,
+ z_jump,
+ z_print_paddr,
+ z_load,
+ z_call_n
+};
+
+void (*var_opcodes[0x40]) (void) = {
+ __illegal__,
+ z_je,
+ z_jl,
+ z_jg,
+ z_dec_chk,
+ z_inc_chk,
+ z_jin,
+ z_test,
+ z_or,
+ z_and,
+ z_test_attr,
+ z_set_attr,
+ z_clear_attr,
+ z_store,
+ z_insert_obj,
+ z_loadw,
+ z_loadb,
+ z_get_prop,
+ z_get_prop_addr,
+ z_get_next_prop,
+ z_add,
+ z_sub,
+ z_mul,
+ z_div,
+ z_mod,
+ z_call_s,
+ z_call_n,
+ z_set_colour,
+ z_throw,
+ __illegal__,
+ __illegal__,
+ __illegal__,
+ z_call_s,
+ z_storew,
+ z_storeb,
+ z_put_prop,
+ z_read,
+ z_print_char,
+ z_print_num,
+ z_random,
+ z_push,
+ z_pull,
+ z_split_window,
+ z_set_window,
+ z_call_s,
+ z_erase_window,
+ z_erase_line,
+ z_set_cursor,
+ z_get_cursor,
+ z_set_text_style,
+ z_buffer_mode,
+ z_output_stream,
+ z_input_stream,
+ z_sound_effect,
+ z_read_char,
+ z_scan_table,
+ z_not,
+ z_call_n,
+ z_call_n,
+ z_tokenise,
+ z_encode_text,
+ z_copy_table,
+ z_print_table,
+ z_check_arg_count
+};
+
+void (*ext_opcodes[0x1d]) (void) = {
+ z_save,
+ z_restore,
+ z_log_shift,
+ z_art_shift,
+ z_set_font,
+ z_draw_picture,
+ z_picture_data,
+ z_erase_picture,
+ z_set_margins,
+ z_save_undo,
+ z_restore_undo,
+ z_print_unicode,
+ z_check_unicode,
+ __illegal__,
+ __illegal__,
+ __illegal__,
+ z_move_window,
+ z_window_size,
+ z_window_style,
+ z_get_wind_prop,
+ z_scroll_window,
+ z_pop_stack,
+ z_read_mouse,
+ z_mouse_window,
+ z_push_stack,
+ z_put_wind_prop,
+ z_print_form,
+ z_make_menu,
+ z_picture_table
+};
+
+
+/*
+ * init_process
+ *
+ * Initialize process variables.
+ *
+ */
+
+void init_process (void)
+{
+ finished = 0;
+} /* init_process */
+
+
+/*
+ * load_operand
+ *
+ * Load an operand, either a variable or a constant.
+ *
+ */
+
+static void load_operand (zbyte type)
+{
+ zword value;
+
+ if (type & 2) { /* variable */
+
+ zbyte variable;
+
+ CODE_BYTE (variable)
+
+ if (variable == 0)
+ value = *sp++;
+ else if (variable < 16)
+ value = *(fp - variable);
+ else {
+ zword addr = h_globals + 2 * (variable - 16);
+ LOW_WORD (addr, value)
+ }
+
+ } else if (type & 1) { /* small constant */
+
+ zbyte bvalue;
+
+ CODE_BYTE (bvalue)
+ value = bvalue;
+
+ } else CODE_WORD (value) /* large constant */
+
+ zargs[zargc++] = value;
+
+}/* load_operand */
+
+/*
+ * load_all_operands
+ *
+ * Given the operand specifier byte, load all (up to four) operands
+ * for a VAR or EXT opcode.
+ *
+ */
+
+static void load_all_operands (zbyte specifier)
+{
+ int i;
+
+ for (i = 6; i >= 0; i -= 2) {
+
+ zbyte type = (specifier >> i) & 0x03;
+
+ if (type == 3)
+ break;
+
+ load_operand (type);
+
+ }
+
+}/* load_all_operands */
+
+/*
+ * interpret
+ *
+ * Z-code interpreter main loop
+ *
+ */
+
+void interpret (void)
+{
+
+ do {
+
+ zbyte opcode;
+
+ CODE_BYTE (opcode)
+
+ zargc = 0;
+
+ if (opcode < 0x80) { /* 2OP opcodes */
+
+ load_operand ((zbyte) (opcode & 0x40) ? 2 : 1);
+ load_operand ((zbyte) (opcode & 0x20) ? 2 : 1);
+
+ var_opcodes[opcode & 0x1f] ();
+
+ } else if (opcode < 0xb0) { /* 1OP opcodes */
+
+ load_operand ((zbyte) (opcode >> 4));
+
+ op1_opcodes[opcode & 0x0f] ();
+
+ } else if (opcode < 0xc0) { /* 0OP opcodes */
+
+ op0_opcodes[opcode - 0xb0] ();
+
+ } else { /* VAR opcodes */
+
+ zbyte specifier1;
+ zbyte specifier2;
+
+ if (opcode == 0xec || opcode == 0xfa) { /* opcodes 0xec */
+ CODE_BYTE (specifier1) /* and 0xfa are */
+ CODE_BYTE (specifier2) /* call opcodes */
+ load_all_operands (specifier1); /* with up to 8 */
+ load_all_operands (specifier2); /* arguments */
+ } else {
+ CODE_BYTE (specifier1)
+ load_all_operands (specifier1);
+ }
+
+ var_opcodes[opcode - 0xc0] ();
+
+ }
+
+#if defined(DJGPP) && defined(SOUND_SUPPORT)
+ if (end_of_sound_flag)
+ end_of_sound ();
+#endif
+
+ } while (finished == 0);
+
+ finished--;
+
+}/* interpret */
+
+/*
+ * call
+ *
+ * Call a subroutine. Save PC and FP then load new PC and initialise
+ * new stack frame. Note that the caller may legally provide less or
+ * more arguments than the function actually has. The call type "ct"
+ * can be 0 (z_call_s), 1 (z_call_n) or 2 (direct call).
+ *
+ */
+
+void call (zword routine, int argc, zword *args, int ct)
+{
+ long pc;
+ zword value;
+ zbyte count;
+ int i;
+
+ if (sp - stack < 4)
+ runtime_error (ERR_STK_OVF);
+
+ GET_PC (pc)
+
+ *--sp = (zword) (pc >> 9);
+ *--sp = (zword) (pc & 0x1ff);
+ *--sp = (zword) (fp - stack - 1);
+ *--sp = (zword) (argc | (ct << (f_setup.save_quetzal ? 12 : 8)));
+
+ fp = sp;
+ frame_count++;
+
+ /* Calculate byte address of routine */
+
+ if (h_version <= V3)
+ pc = (long) routine << 1;
+ else if (h_version <= V5)
+ pc = (long) routine << 2;
+ else if (h_version <= V7)
+ pc = ((long) routine << 2) + ((long) h_functions_offset << 3);
+ else /* h_version == V8 */
+ pc = (long) routine << 3;
+
+ if (pc >= story_size)
+ runtime_error (ERR_ILL_CALL_ADDR);
+
+ SET_PC (pc)
+
+ /* Initialise local variables */
+
+ CODE_BYTE (count)
+
+ if (count > 15)
+ runtime_error (ERR_CALL_NON_RTN);
+ if (sp - stack < count)
+ runtime_error (ERR_STK_OVF);
+
+ if (f_setup.save_quetzal)
+ fp[0] |= (zword) count << 8; /* Save local var count for Quetzal. */
+
+ value = 0;
+
+ for (i = 0; i < count; i++) {
+
+ if (h_version <= V4) /* V1 to V4 games provide default */
+ CODE_WORD (value) /* values for all local variables */
+
+ *--sp = (zword) ((argc-- > 0) ? args[i] : value);
+
+ }
+
+ /* Start main loop for direct calls */
+
+ if (ct == 2)
+ interpret ();
+
+}/* call */
+
+/*
+ * ret
+ *
+ * Return from the current subroutine and restore the previous stack
+ * frame. The result may be stored (0), thrown away (1) or pushed on
+ * the stack (2). In the latter case a direct call has been finished
+ * and we must exit the interpreter loop.
+ *
+ */
+
+void ret (zword value)
+{
+ long pc;
+ int ct;
+
+ if (sp > fp)
+ runtime_error (ERR_STK_UNDF);
+
+ sp = fp;
+
+ ct = *sp++ >> (f_setup.save_quetzal ? 12 : 8);
+ frame_count--;
+ fp = stack + 1 + *sp++;
+ pc = *sp++;
+ pc = ((long) *sp++ << 9) | pc;
+
+ SET_PC (pc)
+
+ /* Handle resulting value */
+
+ if (ct == 0)
+ store (value);
+ if (ct == 2)
+ *--sp = value;
+
+ /* Stop main loop for direct calls */
+
+ if (ct == 2)
+ finished++;
+
+}/* ret */
+
+/*
+ * branch
+ *
+ * Take a jump after an instruction based on the flag, either true or
+ * false. The branch can be short or long; it is encoded in one or two
+ * bytes respectively. When bit 7 of the first byte is set, the jump
+ * takes place if the flag is true; otherwise it is taken if the flag
+ * is false. When bit 6 of the first byte is set, the branch is short;
+ * otherwise it is long. The offset occupies the bottom 6 bits of the
+ * first byte plus all the bits in the second byte for long branches.
+ * Uniquely, an offset of 0 means return false, and an offset of 1 is
+ * return true.
+ *
+ */
+
+void branch (bool flag)
+{
+ long pc;
+ zword offset;
+ zbyte specifier;
+ zbyte off1;
+ zbyte off2;
+
+ CODE_BYTE (specifier)
+
+ off1 = specifier & 0x3f;
+
+ if (!flag)
+ specifier ^= 0x80;
+
+ if (!(specifier & 0x40)) { /* it's a long branch */
+
+ if (off1 & 0x20) /* propagate sign bit */
+ off1 |= 0xc0;
+
+ CODE_BYTE (off2)
+
+ offset = (off1 << 8) | off2;
+
+ } else offset = off1; /* it's a short branch */
+
+ if (specifier & 0x80) {
+
+ if (offset > 1) { /* normal branch */
+
+ GET_PC (pc)
+ pc += (short) offset - 2;
+ SET_PC (pc)
+
+ } else ret (offset); /* special case, return 0 or 1 */
+ }
+
+}/* branch */
+
+/*
+ * store
+ *
+ * Store an operand, either as a variable or pushed on the stack.
+ *
+ */
+
+void store (zword value)
+{
+ zbyte variable;
+
+ CODE_BYTE (variable)
+
+ if (variable == 0)
+ *--sp = value;
+ else if (variable < 16)
+ *(fp - variable) = value;
+ else {
+ zword addr = h_globals + 2 * (variable - 16);
+ SET_WORD (addr, value)
+ }
+
+}/* store */
+
+/*
+ * direct_call
+ *
+ * Call the interpreter loop directly. This is necessary when
+ *
+ * - a sound effect has been finished
+ * - a read instruction has timed out
+ * - a newline countdown has hit zero
+ *
+ * The interpreter returns the result value on the stack.
+ *
+ */
+
+int direct_call (zword addr)
+{
+ zword saved_zargs[8];
+ int saved_zargc;
+ int i;
+
+ /* Calls to address 0 return false */
+
+ if (addr == 0)
+ return 0;
+
+ /* Save operands and operand count */
+
+ for (i = 0; i < 8; i++)
+ saved_zargs[i] = zargs[i];
+
+ saved_zargc = zargc;
+
+ /* Call routine directly */
+
+ call (addr, 0, 0, 2);
+
+ /* Restore operands and operand count */
+
+ for (i = 0; i < 8; i++)
+ zargs[i] = saved_zargs[i];
+
+ zargc = saved_zargc;
+
+ /* Resulting value lies on top of the stack */
+
+ return (short) *sp++;
+
+}/* direct_call */
+
+/*
+ * __extended__
+ *
+ * Load and execute an extended opcode.
+ *
+ */
+
+static void __extended__ (void)
+{
+ zbyte opcode;
+ zbyte specifier;
+
+ CODE_BYTE (opcode)
+ CODE_BYTE (specifier)
+
+ load_all_operands (specifier);
+
+ if (opcode < 0x1d) /* extended opcodes from 0x1d on */
+ ext_opcodes[opcode] (); /* are reserved for future spec' */
+
+}/* __extended__ */
+
+/*
+ * __illegal__
+ *
+ * Exit game because an unknown opcode has been hit.
+ *
+ */
+
+static void __illegal__ (void)
+{
+
+ runtime_error (ERR_ILL_OPCODE);
+
+}/* __illegal__ */
+
+/*
+ * z_catch, store the current stack frame for later use with z_throw.
+ *
+ * no zargs used
+ *
+ */
+
+void z_catch (void)
+{
+
+ store (f_setup.save_quetzal ? frame_count : (zword) (fp - stack));
+
+}/* z_catch */
+
+/*
+ * z_throw, go back to the given stack frame and return the given value.
+ *
+ * zargs[0] = value to return
+ * zargs[1] = stack frame
+ *
+ */
+
+void z_throw (void)
+{
+
+ if (f_setup.save_quetzal) {
+ if (zargs[1] > frame_count)
+ runtime_error (ERR_BAD_FRAME);
+
+ /* Unwind the stack a frame at a time. */
+ for (; frame_count > zargs[1]; --frame_count)
+ fp = stack + 1 + fp[1];
+ } else {
+ if (zargs[1] > STACK_SIZE)
+ runtime_error (ERR_BAD_FRAME);
+
+ fp = stack + zargs[1];
+ }
+
+ ret (zargs[0]);
+
+}/* z_throw */
+
+/*
+ * z_call_n, call a subroutine and discard its result.
+ *
+ * zargs[0] = packed address of subroutine
+ * zargs[1] = first argument (optional)
+ * ...
+ * zargs[7] = seventh argument (optional)
+ *
+ */
+
+void z_call_n (void)
+{
+
+ if (zargs[0] != 0)
+ call (zargs[0], zargc - 1, zargs + 1, 1);
+
+}/* z_call_n */
+
+/*
+ * z_call_s, call a subroutine and store its result.
+ *
+ * zargs[0] = packed address of subroutine
+ * zargs[1] = first argument (optional)
+ * ...
+ * zargs[7] = seventh argument (optional)
+ *
+ */
+
+void z_call_s (void)
+{
+
+ if (zargs[0] != 0)
+ call (zargs[0], zargc - 1, zargs + 1, 0);
+ else
+ store (0);
+
+}/* z_call_s */
+
+/*
+ * z_check_arg_count, branch if subroutine was called with >= n arg's.
+ *
+ * zargs[0] = number of arguments
+ *
+ */
+
+void z_check_arg_count (void)
+{
+
+ if (fp == stack + STACK_SIZE)
+ branch (zargs[0] == 0);
+ else
+ branch (zargs[0] <= (*fp & 0xff));
+
+}/* z_check_arg_count */
+
+/*
+ * z_jump, jump unconditionally to the given address.
+ *
+ * zargs[0] = PC relative address
+ *
+ */
+
+void z_jump (void)
+{
+ long pc;
+
+ GET_PC (pc)
+
+ pc += (short) zargs[0] - 2;
+
+ if (pc >= story_size)
+ runtime_error (ERR_ILL_JUMP_ADDR);
+
+ SET_PC (pc)
+
+}/* z_jump */
+
+/*
+ * z_nop, no operation.
+ *
+ * no zargs used
+ *
+ */
+
+void z_nop (void)
+{
+
+ /* Do nothing */
+
+}/* z_nop */
+
+/*
+ * z_quit, stop game and exit interpreter.
+ *
+ * no zargs used
+ *
+ */
+
+void z_quit (void)
+{
+
+ finished = 9999;
+
+}/* z_quit */
+
+/*
+ * z_ret, return from a subroutine with the given value.
+ *
+ * zargs[0] = value to return
+ *
+ */
+
+void z_ret (void)
+{
+
+ ret (zargs[0]);
+
+}/* z_ret */
+
+/*
+ * z_ret_popped, return from a subroutine with a value popped off the stack.
+ *
+ * no zargs used
+ *
+ */
+
+void z_ret_popped (void)
+{
+
+ ret (*sp++);
+
+}/* z_ret_popped */
+
+/*
+ * z_rfalse, return from a subroutine with false (0).
+ *
+ * no zargs used
+ *
+ */
+
+void z_rfalse (void)
+{
+
+ ret (0);
+
+}/* z_rfalse */
+
+/*
+ * z_rtrue, return from a subroutine with true (1).
+ *
+ * no zargs used
+ *
+ */
+
+void z_rtrue (void)
+{
+
+ ret (1);
+
+}/* z_rtrue */