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-rw-r--r--apps/plugins/frotz/fastmem.c1013
1 files changed, 1013 insertions, 0 deletions
diff --git a/apps/plugins/frotz/fastmem.c b/apps/plugins/frotz/fastmem.c
new file mode 100644
index 0000000000..cdb4bce602
--- /dev/null
+++ b/apps/plugins/frotz/fastmem.c
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+/* fastmem.c - Memory related functions (fast version without virtual memory)
+ * Copyright (c) 1995-1997 Stefan Jokisch
+ *
+ * Changes for Rockbox copyright 2009 Torne Wuff
+ *
+ * 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
+ */
+
+/*
+ * New undo mechanism added by Jim Dunleavy <jim.dunleavy@erha.ie>
+ */
+
+#include "frotz.h"
+
+#define far
+
+extern void seed_random (int);
+extern void restart_screen (void);
+extern void refresh_text_style (void);
+extern void call (zword, int, zword *, int);
+extern void split_window (zword);
+extern void script_open (void);
+extern void script_close (void);
+
+extern zword save_quetzal (int, int);
+extern zword restore_quetzal (int, int);
+
+extern void erase_window (zword);
+
+extern void (*op0_opcodes[]) (void);
+extern void (*op1_opcodes[]) (void);
+extern void (*op2_opcodes[]) (void);
+extern void (*var_opcodes[]) (void);
+
+char save_name[MAX_PATH];
+char auxilary_name[MAX_PATH];
+
+zbyte far *zmp = NULL;
+zbyte far *pcp = NULL;
+
+int story_fp = -1;
+
+/*
+ * Data for the undo mechanism.
+ * This undo mechanism is based on the scheme used in Evin Robertson's
+ * Nitfol interpreter.
+ * Undo blocks are stored as differences between states.
+ */
+
+typedef struct undo_struct undo_t;
+struct undo_struct {
+ undo_t *next;
+ undo_t *prev;
+ long pc;
+ long diff_size;
+ zword frame_count;
+ zword stack_size;
+ zword frame_offset;
+ /* undo diff and stack data follow */
+};
+
+static undo_t *first_undo = NULL, *last_undo = NULL, *curr_undo = NULL;
+static zbyte *prev_zmp, *undo_diff;
+
+static int undo_count = 0;
+
+static void *arena_start = NULL, *arena_end = NULL, *arena_next = NULL;
+
+/*
+ * get_header_extension
+ *
+ * Read a value from the header extension (former mouse table).
+ *
+ */
+
+zword get_header_extension (int entry)
+{
+ zword addr;
+ zword val;
+
+ if (h_extension_table == 0 || entry > hx_table_size)
+ return 0;
+
+ addr = h_extension_table + 2 * entry;
+ LOW_WORD (addr, val)
+
+ return val;
+
+}/* get_header_extension */
+
+/*
+ * set_header_extension
+ *
+ * Set an entry in the header extension (former mouse table).
+ *
+ */
+
+void set_header_extension (int entry, zword val)
+{
+ zword addr;
+
+ if (h_extension_table == 0 || entry > hx_table_size)
+ return;
+
+ addr = h_extension_table + 2 * entry;
+ SET_WORD (addr, val)
+
+}/* set_header_extension */
+
+/*
+ * restart_header
+ *
+ * Set all header fields which hold information about the interpreter.
+ *
+ */
+
+void restart_header (void)
+{
+ zword screen_x_size;
+ zword screen_y_size;
+ zbyte font_x_size;
+ zbyte font_y_size;
+
+ int i;
+
+ SET_BYTE (H_CONFIG, h_config)
+ SET_WORD (H_FLAGS, h_flags)
+
+ if (h_version >= V4) {
+ SET_BYTE (H_INTERPRETER_NUMBER, h_interpreter_number)
+ SET_BYTE (H_INTERPRETER_VERSION, h_interpreter_version)
+ SET_BYTE (H_SCREEN_ROWS, h_screen_rows)
+ SET_BYTE (H_SCREEN_COLS, h_screen_cols)
+ }
+
+ /* It's less trouble to use font size 1x1 for V5 games, especially
+ because of a bug in the unreleased German version of "Zork 1" */
+
+ if (h_version != V6) {
+ screen_x_size = (zword) h_screen_cols;
+ screen_y_size = (zword) h_screen_rows;
+ font_x_size = 1;
+ font_y_size = 1;
+ } else {
+ screen_x_size = h_screen_width;
+ screen_y_size = h_screen_height;
+ font_x_size = h_font_width;
+ font_y_size = h_font_height;
+ }
+
+ if (h_version >= V5) {
+ SET_WORD (H_SCREEN_WIDTH, screen_x_size)
+ SET_WORD (H_SCREEN_HEIGHT, screen_y_size)
+ SET_BYTE (H_FONT_HEIGHT, font_y_size)
+ SET_BYTE (H_FONT_WIDTH, font_x_size)
+ SET_BYTE (H_DEFAULT_BACKGROUND, h_default_background)
+ SET_BYTE (H_DEFAULT_FOREGROUND, h_default_foreground)
+ }
+
+ if (h_version == V6)
+ for (i = 0; i < 8; i++)
+ storeb ((zword) (H_USER_NAME + i), h_user_name[i]);
+
+ SET_BYTE (H_STANDARD_HIGH, h_standard_high)
+ SET_BYTE (H_STANDARD_LOW, h_standard_low)
+
+}/* restart_header */
+
+/*
+ * init_memory
+ *
+ * Allocate memory and load the story file.
+ *
+ */
+
+void init_memory (void)
+{
+ long size;
+ zword addr;
+ unsigned n;
+ int i, j;
+ zbyte *audiobuf;
+ size_t buf_size;
+
+ static struct {
+ enum story story_id;
+ zword release;
+ zbyte serial[6];
+ } records[] = {
+ { SHERLOCK, 21, "871214" },
+ { SHERLOCK, 26, "880127" },
+ { BEYOND_ZORK, 47, "870915" },
+ { BEYOND_ZORK, 49, "870917" },
+ { BEYOND_ZORK, 51, "870923" },
+ { BEYOND_ZORK, 57, "871221" },
+ { ZORK_ZERO, 296, "881019" },
+ { ZORK_ZERO, 366, "890323" },
+ { ZORK_ZERO, 383, "890602" },
+ { ZORK_ZERO, 393, "890714" },
+ { SHOGUN, 292, "890314" },
+ { SHOGUN, 295, "890321" },
+ { SHOGUN, 311, "890510" },
+ { SHOGUN, 322, "890706" },
+ { ARTHUR, 54, "890606" },
+ { ARTHUR, 63, "890622" },
+ { ARTHUR, 74, "890714" },
+ { JOURNEY, 26, "890316" },
+ { JOURNEY, 30, "890322" },
+ { JOURNEY, 77, "890616" },
+ { JOURNEY, 83, "890706" },
+ { LURKING_HORROR, 203, "870506" },
+ { LURKING_HORROR, 219, "870912" },
+ { LURKING_HORROR, 221, "870918" },
+ { UNKNOWN, 0, "------" }
+ };
+
+ /* Open story file */
+
+ if ((story_fp = rb->open(story_name, O_RDONLY)) < 0)
+ os_fatal ("Cannot open story file");
+
+ /* Allocate memory for story header */
+
+ zmp = rb->plugin_get_buffer(&buf_size);
+
+ /* Load header into memory */
+
+ if (fread (zmp, 1, 64, story_fp) != 64)
+ os_fatal ("Story file read error");
+
+ /* Copy header fields to global variables */
+
+ LOW_BYTE (H_VERSION, h_version)
+
+ if (h_version < V1 || h_version > V8)
+ os_fatal ("Unknown Z-code version");
+
+ LOW_BYTE (H_CONFIG, h_config)
+
+ if (h_version == V3 && (h_config & CONFIG_BYTE_SWAPPED))
+ os_fatal ("Byte swapped story file");
+
+ LOW_WORD (H_RELEASE, h_release)
+ LOW_WORD (H_RESIDENT_SIZE, h_resident_size)
+ LOW_WORD (H_START_PC, h_start_pc)
+ LOW_WORD (H_DICTIONARY, h_dictionary)
+ LOW_WORD (H_OBJECTS, h_objects)
+ LOW_WORD (H_GLOBALS, h_globals)
+ LOW_WORD (H_DYNAMIC_SIZE, h_dynamic_size)
+ LOW_WORD (H_FLAGS, h_flags)
+
+ for (i = 0, addr = H_SERIAL; i < 6; i++, addr++)
+ LOW_BYTE (addr, h_serial[i])
+
+ /* Auto-detect buggy story files that need special fixes */
+
+ story_id = UNKNOWN;
+
+ for (i = 0; records[i].story_id != UNKNOWN; i++) {
+
+ if (h_release == records[i].release) {
+
+ for (j = 0; j < 6; j++)
+ if (h_serial[j] != records[i].serial[j])
+ goto no_match;
+
+ story_id = records[i].story_id;
+
+ }
+
+ no_match: ; /* null statement */
+
+ }
+
+ LOW_WORD (H_ABBREVIATIONS, h_abbreviations)
+ LOW_WORD (H_FILE_SIZE, h_file_size)
+
+ /* Calculate story file size in bytes */
+
+ if (h_file_size != 0) {
+
+ story_size = (long) 2 * h_file_size;
+
+ if (h_version >= V4)
+ story_size *= 2;
+ if (h_version >= V6)
+ story_size *= 2;
+
+ } else { /* some old games lack the file size entry */
+
+ fseek (story_fp, 0, SEEK_END);
+ story_size = ftell (story_fp);
+ fseek (story_fp, 64, SEEK_SET);
+
+ }
+
+ LOW_WORD (H_CHECKSUM, h_checksum)
+ LOW_WORD (H_ALPHABET, h_alphabet)
+ LOW_WORD (H_FUNCTIONS_OFFSET, h_functions_offset)
+ LOW_WORD (H_STRINGS_OFFSET, h_strings_offset)
+ LOW_WORD (H_TERMINATING_KEYS, h_terminating_keys)
+ LOW_WORD (H_EXTENSION_TABLE, h_extension_table)
+
+ /* Zork Zero Macintosh doesn't have the graphics flag set */
+
+ if (story_id == ZORK_ZERO && h_release == 296)
+ h_flags |= GRAPHICS_FLAG;
+
+ /* Adjust opcode tables */
+
+ if (h_version <= V4) {
+ op0_opcodes[0x09] = z_pop;
+ op1_opcodes[0x0f] = z_not;
+ } else {
+ op0_opcodes[0x09] = z_catch;
+ op1_opcodes[0x0f] = z_call_n;
+ }
+
+ /* Allocate memory for story data */
+
+ if ((size_t)story_size > buf_size)
+ {
+ audiobuf = rb->plugin_get_audio_buffer(&buf_size);
+ if ((size_t)story_size > buf_size)
+ os_fatal ("Out of memory");
+ rb->memcpy(audiobuf, zmp, 64);
+ zmp = audiobuf;
+ }
+
+ /* Assign left over memory as the arena for undo alloc */
+ arena_start = arena_next = (void*)((int)(zmp + story_size + 3) & ~3);
+ arena_end = zmp + buf_size;
+
+ /* Load story file in chunks of 32KB */
+
+ n = 0x8000;
+
+ for (size = 64; size < story_size; size += n) {
+
+ if (story_size - size < 0x8000)
+ n = (unsigned) (story_size - size);
+
+ SET_PC (size)
+
+ if (fread (pcp, 1, n, story_fp) != (signed)n)
+ os_fatal ("Story file read error");
+
+ }
+
+ /* Read header extension table */
+
+ hx_table_size = get_header_extension (HX_TABLE_SIZE);
+ hx_unicode_table = get_header_extension (HX_UNICODE_TABLE);
+
+}/* init_memory */
+
+/*
+ * init_undo
+ *
+ * Allocate memory for multiple undo. It is important not to occupy
+ * all the memory available, since the IO interface may need memory
+ * during the game, e.g. for loading sounds or pictures.
+ *
+ */
+
+void init_undo (void)
+{
+ /* Allocate h_dynamic_size bytes for previous dynamic zmp state
+ + 1.5 h_dynamic_size for Quetzal diff + 2. */
+ int size = (h_dynamic_size * 5) / 2 + 2;
+ if ((arena_end - arena_start) >= size) {
+ prev_zmp = arena_start;
+ undo_diff = arena_start + h_dynamic_size;
+ arena_start = (void*)((int)(arena_start + size + 3) & ~3);
+ arena_next = arena_start;
+ memcpy (prev_zmp, zmp, h_dynamic_size);
+ } else
+ f_setup.undo_slots = 0;
+
+}/* init_undo */
+
+/*
+ * free_undo
+ *
+ * Free count undo blocks from the beginning of the undo list.
+ *
+ */
+
+static void free_undo (int count)
+{
+ undo_t *p;
+
+ if (count > undo_count)
+ count = undo_count;
+ while (count--) {
+ p = first_undo;
+ if (curr_undo == first_undo)
+ curr_undo = curr_undo->next;
+ first_undo = first_undo->next;
+ undo_count--;
+ }
+ if (first_undo)
+ first_undo->prev = NULL;
+ else
+ last_undo = NULL;
+}/* free_undo */
+
+/*
+ * reset_memory
+ *
+ * Close the story file and deallocate memory.
+ *
+ */
+
+void reset_memory (void)
+{
+ if (story_fp != -1)
+ fclose (story_fp);
+ story_fp = -1;
+
+ free_undo (undo_count);
+ undo_count = 0;
+
+ arena_start = NULL;
+ arena_end = NULL;
+ arena_next = NULL;
+ zmp = NULL;
+}/* reset_memory */
+
+/*
+ * storeb
+ *
+ * Write a byte value to the dynamic Z-machine memory.
+ *
+ */
+
+void storeb (zword addr, zbyte value)
+{
+
+ if (addr >= h_dynamic_size)
+ runtime_error (ERR_STORE_RANGE);
+
+ if (addr == H_FLAGS + 1) { /* flags register is modified */
+
+ h_flags &= ~(SCRIPTING_FLAG | FIXED_FONT_FLAG);
+ h_flags |= value & (SCRIPTING_FLAG | FIXED_FONT_FLAG);
+
+ if (value & SCRIPTING_FLAG) {
+ if (!ostream_script)
+ script_open ();
+ } else {
+ if (ostream_script)
+ script_close ();
+ }
+
+ refresh_text_style ();
+
+ }
+
+ SET_BYTE (addr, value)
+
+}/* storeb */
+
+/*
+ * storew
+ *
+ * Write a word value to the dynamic Z-machine memory.
+ *
+ */
+
+void storew (zword addr, zword value)
+{
+
+ storeb ((zword) (addr + 0), hi (value));
+ storeb ((zword) (addr + 1), lo (value));
+
+}/* storew */
+
+/*
+ * z_restart, re-load dynamic area, clear the stack and set the PC.
+ *
+ * no zargs used
+ *
+ */
+
+void z_restart (void)
+{
+ static bool first_restart = TRUE;
+
+ flush_buffer ();
+
+ os_restart_game (RESTART_BEGIN);
+
+ seed_random (0);
+
+ if (!first_restart) {
+
+ fseek (story_fp, 0, SEEK_SET);
+
+ if (fread (zmp, 1, h_dynamic_size, story_fp) != h_dynamic_size)
+ os_fatal ("Story file read error");
+
+ } else first_restart = FALSE;
+
+ restart_header ();
+ restart_screen ();
+
+ sp = fp = stack + STACK_SIZE;
+ frame_count = 0;
+
+ if (h_version != V6) {
+
+ long pc = (long) h_start_pc;
+ SET_PC (pc)
+
+ } else call (h_start_pc, 0, NULL, 0);
+
+ os_restart_game (RESTART_END);
+
+}/* z_restart */
+
+/*
+ * get_default_name
+ *
+ * Read a default file name from the memory of the Z-machine and
+ * copy it to a string.
+ *
+ */
+
+static void get_default_name (char *default_name, zword addr)
+{
+
+ if (addr != 0) {
+
+ zbyte len;
+ int i;
+
+ LOW_BYTE (addr, len)
+ addr++;
+
+ for (i = 0; i < len; i++) {
+
+ zbyte c;
+
+ LOW_BYTE (addr, c)
+ addr++;
+
+ if (c >= 'A' && c <= 'Z')
+ c += 'a' - 'A';
+
+ default_name[i] = c;
+
+ }
+
+ default_name[i] = 0;
+
+ if (strchr (default_name, '.') == NULL)
+ strcpy (default_name + i, ".AUX");
+
+ } else strcpy (default_name, auxilary_name);
+
+}/* get_default_name */
+
+/*
+ * z_restore, restore [a part of] a Z-machine state from disk
+ *
+ * zargs[0] = address of area to restore (optional)
+ * zargs[1] = number of bytes to restore
+ * zargs[2] = address of suggested file name
+ *
+ */
+
+void z_restore (void)
+{
+ char new_name[MAX_PATH];
+ char default_name[MAX_PATH];
+ int gfp;
+
+ zword success = 0;
+
+ if (zargc != 0) {
+
+ /* Get the file name */
+
+ get_default_name (default_name, (zargc >= 3) ? zargs[2] : 0);
+
+ if (os_read_file_name (new_name, default_name, FILE_LOAD_AUX) == 0)
+ goto finished;
+
+ strcpy (auxilary_name, default_name);
+
+ /* Open auxilary file */
+
+ if ((gfp = rb->open (new_name, O_RDONLY)) < 0)
+ goto finished;
+
+ /* Load auxilary file */
+
+ success = fread (zmp + zargs[0], 1, zargs[1], gfp);
+
+ /* Close auxilary file */
+
+ fclose (gfp);
+
+ } else {
+
+ /* Get the file name */
+
+ if (os_read_file_name (new_name, save_name, FILE_RESTORE) == 0)
+ goto finished;
+
+ strcpy (save_name, new_name);
+
+ /* Open game file */
+
+ if ((gfp = rb->open (new_name, O_RDONLY)) < 0)
+ goto finished;
+
+ success = restore_quetzal (gfp, story_fp);
+
+ /* Close game file */
+
+ fclose (gfp);
+
+ if ((short) success >= 0) {
+
+ if ((short) success > 0) {
+ zbyte old_screen_rows;
+ zbyte old_screen_cols;
+
+ /* In V3, reset the upper window. */
+ if (h_version == V3)
+ split_window (0);
+
+ LOW_BYTE (H_SCREEN_ROWS, old_screen_rows);
+ LOW_BYTE (H_SCREEN_COLS, old_screen_cols);
+
+ /* Reload cached header fields. */
+ restart_header ();
+
+ /*
+ * Since QUETZAL files may be saved on many different machines,
+ * the screen sizes may vary a lot. Erasing the status window
+ * seems to cover up most of the resulting badness.
+ */
+ if (h_version > V3 && h_version != V6
+ && (h_screen_rows != old_screen_rows
+ || h_screen_cols != old_screen_cols))
+ erase_window (1);
+ }
+ } else
+ os_fatal ("Error reading save file");
+ }
+
+finished:
+
+ if (h_version <= V3)
+ branch (success);
+ else
+ store (success);
+
+}/* z_restore */
+
+/*
+ * mem_diff
+ *
+ * Set diff to a Quetzal-like difference between a and b,
+ * copying a to b as we go. It is assumed that diff points to a
+ * buffer which is large enough to hold the diff.
+ * mem_size is the number of bytes to compare.
+ * Returns the number of bytes copied to diff.
+ *
+ */
+
+static long mem_diff (zbyte *a, zbyte *b, zword mem_size, zbyte *diff)
+{
+ unsigned size = mem_size;
+ zbyte *p = diff;
+ unsigned j;
+ zbyte c;
+
+ for (;;) {
+ for (j = 0; size > 0 && (c = *a++ ^ *b++) == 0; j++)
+ size--;
+ if (size == 0) break;
+ size--;
+ if (j > 0x8000) {
+ *p++ = 0;
+ *p++ = 0xff;
+ *p++ = 0xff;
+ j -= 0x8000;
+ }
+ if (j > 0) {
+ *p++ = 0;
+ j--;
+ if (j <= 0x7f) {
+ *p++ = j;
+ } else {
+ *p++ = (j & 0x7f) | 0x80;
+ *p++ = (j & 0x7f80) >> 7;
+ }
+ }
+ *p++ = c;
+ *(b - 1) ^= c;
+ }
+ return p - diff;
+}/* mem_diff */
+
+/*
+ * mem_undiff
+ *
+ * Applies a quetzal-like diff to dest
+ *
+ */
+
+static void mem_undiff (zbyte *diff, long diff_length, zbyte *dest)
+{
+ zbyte c;
+
+ while (diff_length) {
+ c = *diff++;
+ diff_length--;
+ if (c == 0) {
+ unsigned runlen;
+
+ if (!diff_length)
+ return; /* Incomplete run */
+ runlen = *diff++;
+ diff_length--;
+ if (runlen & 0x80) {
+ if (!diff_length)
+ return; /* Incomplete extended run */
+ c = *diff++;
+ diff_length--;
+ runlen = (runlen & 0x7f) | (((unsigned) c) << 7);
+ }
+
+ dest += runlen + 1;
+ } else {
+ *dest++ ^= c;
+ }
+ }
+}/* mem_undiff */
+
+/*
+ * restore_undo
+ *
+ * This function does the dirty work for z_restore_undo.
+ *
+ */
+
+int restore_undo (void)
+{
+
+ if (f_setup.undo_slots == 0) /* undo feature unavailable */
+
+ return -1;
+
+ if (curr_undo == NULL) /* no saved game state */
+
+ return 0;
+
+ /* undo possible */
+
+ memcpy (zmp, prev_zmp, h_dynamic_size);
+ SET_PC (curr_undo->pc)
+ sp = stack + STACK_SIZE - curr_undo->stack_size;
+ fp = stack + curr_undo->frame_offset;
+ frame_count = curr_undo->frame_count;
+ mem_undiff ((zbyte *) (curr_undo + 1), curr_undo->diff_size, prev_zmp);
+ memcpy (sp, (zbyte *)(curr_undo + 1) + curr_undo->diff_size,
+ curr_undo->stack_size * sizeof (*sp));
+
+ curr_undo = curr_undo->prev;
+
+ restart_header ();
+
+ return 2;
+
+}/* restore_undo */
+
+/*
+ * z_restore_undo, restore a Z-machine state from memory.
+ *
+ * no zargs used
+ *
+ */
+
+void z_restore_undo (void)
+{
+
+ store ((zword) restore_undo ());
+
+}/* z_restore_undo */
+
+/*
+ * z_save, save [a part of] the Z-machine state to disk.
+ *
+ * zargs[0] = address of memory area to save (optional)
+ * zargs[1] = number of bytes to save
+ * zargs[2] = address of suggested file name
+ *
+ */
+
+void z_save (void)
+{
+ char new_name[MAX_PATH];
+ char default_name[MAX_PATH];
+ int gfp;
+
+ zword success = 0;
+
+ if (zargc != 0) {
+
+ /* Get the file name */
+
+ get_default_name (default_name, (zargc >= 3) ? zargs[2] : 0);
+
+ if (os_read_file_name (new_name, default_name, FILE_SAVE_AUX) == 0)
+ goto finished;
+
+ strcpy (auxilary_name, default_name);
+
+ /* Open auxilary file */
+
+ if ((gfp = rb->open (new_name, O_WRONLY|O_CREAT|O_TRUNC)) < 0)
+ goto finished;
+
+ /* Write auxilary file */
+
+ success = fwrite (zmp + zargs[0], zargs[1], 1, gfp);
+
+ /* Close auxilary file */
+
+ fclose (gfp);
+
+ } else {
+
+ /* Get the file name */
+
+ if (os_read_file_name (new_name, save_name, FILE_SAVE) == 0)
+ goto finished;
+
+ strcpy (save_name, new_name);
+
+ /* Open game file */
+
+ if ((gfp = rb->open (new_name, O_WRONLY|O_CREAT|O_TRUNC)) < 0)
+ goto finished;
+
+ success = save_quetzal (gfp, story_fp);
+
+ /* Close game file and check for errors */
+
+ if (fclose (gfp) != 0 || ferror (story_fp)) {
+ print_string ("Error writing save file\n");
+ goto finished;
+ }
+
+ /* Success */
+
+ success = 1;
+
+ }
+
+finished:
+
+ if (h_version <= V3)
+ branch (success);
+ else
+ store (success);
+
+}/* z_save */
+
+/*
+ * save_undo
+ *
+ * This function does the dirty work for z_save_undo.
+ *
+ */
+
+int save_undo (void)
+{
+ long diff_size;
+ zword stack_size;
+ int size;
+ undo_t *p;
+
+ if (f_setup.undo_slots == 0) /* undo feature unavailable */
+ return -1;
+
+ /* save undo possible */
+
+ while (last_undo != curr_undo) {
+ p = last_undo;
+ last_undo = last_undo->prev;
+ arena_next = p;
+ undo_count--;
+ }
+ if (last_undo)
+ last_undo->next = NULL;
+ else
+ first_undo = NULL;
+
+ if (undo_count == f_setup.undo_slots)
+ free_undo (1);
+
+ diff_size = mem_diff (zmp, prev_zmp, h_dynamic_size, undo_diff);
+ stack_size = stack + STACK_SIZE - sp;
+ do {
+ size = sizeof (undo_t) + diff_size + stack_size * sizeof (*sp);
+ if (arena_next > (void*)first_undo) {
+ /* Free space is all at the end */
+ if ((arena_end - arena_next) >= size) {
+ /* Trivial: enough room at the end */
+ p = arena_next;
+ arena_next = (void*)((int)(arena_next + size + 3) & ~3);
+ } else {
+ /* Need to wrap */
+ arena_next = arena_start;
+ p = NULL;
+ }
+ } else {
+ /* Free space is somewhere else */
+ if (((void*)first_undo - arena_next) >= size) {
+ /* There is room before the "first" undo */
+ p = arena_next;
+ arena_next = (void*)((int)(arena_next + size + 3) & ~3);
+ } else {
+ /* Not enough room, just need to free some */
+ p = NULL;
+ }
+ }
+
+ if (p == NULL)
+ free_undo (1);
+ } while (!p && undo_count);
+ if (p == NULL)
+ return -1;
+ GET_PC (p->pc)
+ p->frame_count = frame_count;
+ p->diff_size = diff_size;
+ p->stack_size = stack_size;
+ p->frame_offset = fp - stack;
+ memcpy (p + 1, undo_diff, diff_size);
+ memcpy ((zbyte *)(p + 1) + diff_size, sp, stack_size * sizeof (*sp));
+
+ if (!first_undo) {
+ p->prev = NULL;
+ first_undo = p;
+ } else {
+ last_undo->next = p;
+ p->prev = last_undo;
+ }
+ p->next = NULL;
+ curr_undo = last_undo = p;
+ undo_count++;
+ return 1;
+
+}/* save_undo */
+
+/*
+ * z_save_undo, save the current Z-machine state for a future undo.
+ *
+ * no zargs used
+ *
+ */
+
+void z_save_undo (void)
+{
+
+ store ((zword) save_undo ());
+
+}/* z_save_undo */
+
+/*
+ * z_verify, check the story file integrity.
+ *
+ * no zargs used
+ *
+ */
+
+void z_verify (void)
+{
+ zword checksum = 0;
+ long i;
+
+ /* Sum all bytes in story file except header bytes */
+
+ fseek (story_fp, 64, SEEK_SET);
+
+ for (i = 64; i < story_size; i++)
+ checksum += fgetc (story_fp);
+
+ /* Branch if the checksums are equal */
+
+ branch (checksum == h_checksum);
+
+}/* z_verify */