SDLPoP-1.22/src/replay.c

/*
SDLPoP, a port/conversion of the DOS game Prince of Persia.
Copyright (C) 2013-2021  Dávid Nagy

This program 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 3 of the License, or
(at your option) any later version.

This program 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, see <https://www.gnu.org/licenses/>.

The authors of this program may be contacted at https://forum.princed.org
*/

#include "common.h"
#include <time.h>

#ifdef USE_REPLAY

const char replay_magic_number[3] = "P1R";
const word replay_format_class = 0;          // unique number associated with this SDLPoP implementation / fork
const char* implementation_name = "SDLPoP v" SDLPOP_VERSION;

#define REPLAY_FORMAT_CURR_VERSION       102 // current version number of the replay format
#define REPLAY_FORMAT_MIN_VERSION        101 // SDLPoP will open replays with this version number and higher
#define REPLAY_FORMAT_DEPRECATION_NUMBER 2   // SDLPoP won't open replays with a higher deprecation number
// If deprecation_number >= 2: Waste an RNG cycle in loose_shake() to match DOS PoP.

#define MAX_REPLAY_DURATION 345600 // 8 hours: 720 * 60 * 8 ticks
byte moves[MAX_REPLAY_DURATION] = {0}; // static memory for now because it is easier (should this be dynamic?)

char replay_levelset_name[POP_MAX_PATH];
char stored_levelset_name[POP_MAX_PATH];

// 1-byte structure representing which controls were active at a particular game tick
typedef union replay_move_type {
	struct {
		sbyte x : 2;
		sbyte y : 2;
		byte shift : 1;
		byte special : 3; // enum replay_special_moves, see types.h
	};
	byte bits;
} replay_move_type;

//dword curr_tick = 0;

FILE* replay_fp = NULL;
byte replay_file_open = 0;
int current_replay_number = 0;
int next_replay_number = 0;

byte* savestate_buffer = NULL;
dword savestate_offset = 0;
dword savestate_size = 0;
#define MAX_SAVESTATE_SIZE 4096

// These are defined in seg000.c:
typedef int process_func_type(void* data, size_t data_size);
extern int quick_process(process_func_type process_func);
extern const char quick_version[9];

// header information read from the first part of a replay file
typedef struct replay_header_type {
	byte uses_custom_levelset;
	char levelset_name[POP_MAX_PATH];
	char implementation_name[POP_MAX_PATH];
} replay_header_type;

// information needed to keep track of all listed replay files, and to sort them by their creation date
typedef struct replay_info_type {
	char filename[POP_MAX_PATH];
	time_t creation_time;
	replay_header_type header;
} replay_info_type;

#define REPLAY_HEADER_ERROR_MESSAGE_MAX 512

#define fread_check(dst, size, elements, fp)	do {		\
		size_t __count;					\
		__count = fread(dst, size, elements, fp);	\
		if (__count != (elements)) {			\
			if (error_message != NULL) {		\
				snprintf_check(error_message, REPLAY_HEADER_ERROR_MESSAGE_MAX,\
					       #dst " missing -- not a valid replay file!");\
			}					\
                return 0; /* incompatible file */		\
                }						\
	} while (0)

int read_replay_header(replay_header_type* header, FILE* fp, char* error_message) {
	// Explicitly go to the beginning, because the current filepos might be nonzero.
	fseek(fp, 0, SEEK_SET);
	// read the magic number
	char magic[3] = "";
	fread_check(magic, 3, 1, fp);
	if (strncmp(magic, replay_magic_number, 3) != 0) {
		if (error_message != NULL) {
			snprintf_check(error_message, REPLAY_HEADER_ERROR_MESSAGE_MAX, "not a valid replay file!");
		}
		return 0; // incompatible, magic number not correct!
	}
	// read the unique number associated with this SDLPoP implementation / fork (for normal SDLPoP: 0)
	word class;
	fread_check(&class, sizeof(class), 1, fp);
	// read the format version number
	byte version_number = (byte) fgetc(fp);
	// read the format deprecation number
	byte deprecation_number = (byte) fgetc(fp);

	// creation time (seconds since 1970) is embedded in the format, but not used in SDLPoP right now
	fseek(fp, sizeof(Sint64), SEEK_CUR);

	// read the levelset_name
	byte len_read = (byte) fgetc(fp);
	header->uses_custom_levelset = (len_read != 0);
	fread_check(header->levelset_name, sizeof(char), len_read, fp);
	header->levelset_name[len_read] = '\0';

	// read the implementation_name
	len_read = (byte) fgetc(fp);
	fread_check(header->implementation_name, sizeof(char), len_read, fp);
	header->implementation_name[len_read] = '\0';

	if (class != replay_format_class) {
		// incompatible, replay format is associated with a different implementation of SDLPoP
		if (error_message != NULL) {
			snprintf_check(error_message, REPLAY_HEADER_ERROR_MESSAGE_MAX,
			         "replay created with \"%s\"...\nIncompatible replay class identifier! (expected %d, found %d)",
			         header->implementation_name, replay_format_class, class);
		}
		return 0;
	}

	if (version_number < REPLAY_FORMAT_MIN_VERSION) {
		// incompatible, replay format is too old
		if (error_message != NULL) {
			snprintf_check(error_message, REPLAY_HEADER_ERROR_MESSAGE_MAX,
			         "replay created with \"%s\"...\nReplay format version too old! (minimum %d, found %d)",
			         header->implementation_name, REPLAY_FORMAT_MIN_VERSION, version_number);
		}
		return 0;
	}

	if (deprecation_number > REPLAY_FORMAT_DEPRECATION_NUMBER) {
		// incompatible, replay format is too new
		if (error_message != NULL) {
			snprintf_check(error_message, REPLAY_HEADER_ERROR_MESSAGE_MAX,
			         "replay created with \"%s\"...\nReplay deprecation number too new! (max %d, found %d)",
			         header->implementation_name, REPLAY_FORMAT_DEPRECATION_NUMBER, deprecation_number);
		}
		return 0;
	}

	g_deprecation_number = deprecation_number;

	if (is_validate_mode) {
		static byte is_replay_info_printed = 0;
		if (!is_replay_info_printed) {
			printf("\nReplay created with %s.\n", header->implementation_name);
			printf("Format: class identifier %d, version number %d, deprecation number %d.\n",
			       class, version_number, deprecation_number);
			if (header->levelset_name[0] == '\0') {
				printf("Levelset: original Prince of Persia.\n");
			} else {
				printf("Levelset: %s.\n", header->levelset_name);
			}
			putchar('\n');
			is_replay_info_printed = 1; // do this only once
		}
	}

	return 1;
}

int num_replay_files = 0; // number of listed replays
int max_replay_files = 128; // initially, may grow if there are > 128 replay files found
replay_info_type* replay_list = NULL;

// Compare function -- for qsort() in list_replay_files() below
// Compares creation dates of replays, so they can be loaded in reverse creation order (newest first)
static int compare_replay_creation_time(const void* a, const void* b) {
	return (int) difftime( ((replay_info_type*)b)->creation_time, ((replay_info_type*)a)->creation_time );
}

void list_replay_files() {

	if (replay_list == NULL) {
		// need to allocate enough memory to store info about all replay files in the directory
		replay_list = malloc( max_replay_files * sizeof( replay_info_type ) ); // will realloc() later if > 256 files exist
	}

	num_replay_files = 0;

	directory_listing_type* directory_listing = create_directory_listing_and_find_first_file(replays_folder, "p1r");
	if (directory_listing == NULL) {
		return;
	}

	do {
		++num_replay_files;
		if (num_replay_files > max_replay_files) {
			// too many files, expand the memory available for replay_list
			max_replay_files += 128;
			replay_list = realloc( replay_list, max_replay_files * sizeof( replay_info_type ) );
		}
		replay_info_type* replay_info = &replay_list[num_replay_files - 1]; // current replay file
		memset( replay_info, 0, sizeof( replay_info_type ) );
		// store the filename of the replay
		snprintf_check(replay_info->filename, POP_MAX_PATH, "%s/%s", replays_folder,
					get_current_filename_from_directory_listing(directory_listing) );

		// get the creation time
		struct stat st;
		if (stat( replay_info->filename, &st ) == 0) {
			replay_info->creation_time = st.st_ctime;
		}
		// read and store the levelset name associated with the replay
		FILE* fp = fopen( replay_info->filename, "rb" );
		int ok = 0;
		if (fp != NULL) {
			ok = read_replay_header( &replay_info->header, fp, NULL );
			fclose( fp );
		}
		if (!ok) --num_replay_files; // scrap the file if it is not compatible

	} while (find_next_file(directory_listing));

	close_directory_listing(directory_listing);

	if (num_replay_files > 1) {
		// sort listed replays by their creation date
		qsort( replay_list, (size_t) num_replay_files, sizeof( replay_info_type ), compare_replay_creation_time );
	}
};

byte open_replay_file(const char *filename) {
	printf("Opening replay file: %s\n", filename);
	if (replay_file_open) fclose(replay_fp);
	replay_fp = fopen(filename, "rb");
	if (replay_fp != NULL) {
		replay_file_open = 1;
		return 1;
	}
	else {
		replay_file_open = 0;
		return 0;
	}
}

void change_working_dir_to_sdlpop_root() {
	char* exe_path = g_argv[0];
	// strip away everything after the last slash or backslash in the path
	int len;
	for (len = strlen(exe_path); len > 0; --len) {
		if (exe_path[len] == '\\' || exe_path[len] == '/') {
			break;
		}
	}
	if (len > 0) {
		char exe_dir[POP_MAX_PATH];
		strncpy(exe_dir, exe_path, len);
		exe_dir[len] = '\0';

		int result = chdir(exe_dir);
		if (result != 0) {
			perror("Can't change into SDLPoP directory");
		}
	}

};

// Called in pop_main(); check whether a replay file is being opened directly (double-clicked, dragged onto .exe, etc.)
void start_with_replay_file(const char *filename) {
	if (open_replay_file(filename)) {
		change_working_dir_to_sdlpop_root();
		current_replay_number = -1; // don't cycle when pressing Tab
		// We should read the header in advance so we know the levelset name
		// then the game can immediately load the correct resources
		replay_header_type header = {0};
		char header_error_message[REPLAY_HEADER_ERROR_MESSAGE_MAX];
		int ok = read_replay_header(&header, replay_fp, header_error_message);
		if (!ok) {
			char error_message[REPLAY_HEADER_ERROR_MESSAGE_MAX];
			snprintf_check(error_message, REPLAY_HEADER_ERROR_MESSAGE_MAX,
			         "Error opening replay file: %s\n",
			         header_error_message);
			fprintf(stderr, "%s", error_message);
			fclose(replay_fp);
			replay_fp = NULL;
			replay_file_open = 0;

			if (is_validate_mode) // Validating replays is cmd-line only, so, no sense continuing from here.
				exit(0);

			SDL_ShowSimpleMessageBox(SDL_MESSAGEBOX_ERROR, "SDLPoP", error_message, NULL);
			return;
		}
		if (header.uses_custom_levelset) {
			strncpy(replay_levelset_name, header.levelset_name, sizeof(replay_levelset_name)); // use the replays's levelset
		}
		rewind(replay_fp); // replay file is still open and will be read in load_replay() later
		need_start_replay = 1; // will later call start_replay(), from init_record_replay()
	}
}

// The functions options_process_* below each process (read/write) a section of options variables (using SDL_RWops)
// This is I/O for the *binary* representation of the relevant options - this gets saved as part of a replay.

typedef int rw_process_func_type(SDL_RWops* rw, void* data, size_t data_size);
typedef void process_options_section_func_type(SDL_RWops* rw, rw_process_func_type process_func);

#define process(x) if (!process_func(rw, &(x), sizeof(x))) return

void options_process_features(SDL_RWops* rw, rw_process_func_type process_func) {
	process(enable_copyprot);
	process(enable_quicksave);
	process(enable_quicksave_penalty);
}

fixes_options_type fixes_options_replay;

void options_process_enhancements(SDL_RWops* rw, rw_process_func_type process_func) {
	process(use_fixes_and_enhancements);
	process(fixes_options_replay.enable_crouch_after_climbing);
	process(fixes_options_replay.enable_freeze_time_during_end_music);
	process(fixes_options_replay.enable_remember_guard_hp);
}

void options_process_fixes(SDL_RWops* rw, rw_process_func_type process_func) {
	process(fixes_options_replay.fix_gate_sounds);
	process(fixes_options_replay.fix_two_coll_bug);
	process(fixes_options_replay.fix_infinite_down_bug);
	process(fixes_options_replay.fix_gate_drawing_bug);
	process(fixes_options_replay.fix_bigpillar_climb);
	process(fixes_options_replay.fix_jump_distance_at_edge);
	process(fixes_options_replay.fix_edge_distance_check_when_climbing);
	process(fixes_options_replay.fix_painless_fall_on_guard);
	process(fixes_options_replay.fix_wall_bump_triggers_tile_below);
	process(fixes_options_replay.fix_stand_on_thin_air);
	process(fixes_options_replay.fix_press_through_closed_gates);
	process(fixes_options_replay.fix_grab_falling_speed);
	process(fixes_options_replay.fix_skeleton_chomper_blood);
	process(fixes_options_replay.fix_move_after_drink);
	process(fixes_options_replay.fix_loose_left_of_potion);
	process(fixes_options_replay.fix_guard_following_through_closed_gates);
	process(fixes_options_replay.fix_safe_landing_on_spikes);
	process(fixes_options_replay.fix_glide_through_wall);
	process(fixes_options_replay.fix_drop_through_tapestry);
	process(fixes_options_replay.fix_land_against_gate_or_tapestry);
	process(fixes_options_replay.fix_unintended_sword_strike);
	process(fixes_options_replay.fix_retreat_without_leaving_room);
	process(fixes_options_replay.fix_running_jump_through_tapestry);
	process(fixes_options_replay.fix_push_guard_into_wall);
	process(fixes_options_replay.fix_jump_through_wall_above_gate);
	process(fixes_options_replay.fix_chompers_not_starting);
	process(fixes_options_replay.fix_feather_interrupted_by_leveldoor);
	process(fixes_options_replay.fix_offscreen_guards_disappearing);
	process(fixes_options_replay.fix_move_after_sheathe);
	process(fixes_options_replay.fix_hidden_floors_during_flashing);
	process(fixes_options_replay.fix_hang_on_teleport);
	process(fixes_options_replay.fix_exit_door);
	process(fixes_options_replay.fix_quicksave_during_feather);
	process(fixes_options_replay.fix_caped_prince_sliding_through_gate);
	process(fixes_options_replay.fix_doortop_disabling_guard);
}

void options_process_custom_general(SDL_RWops* rw, rw_process_func_type process_func) {
	process(custom->start_minutes_left);
	process(custom->start_ticks_left);
	process(custom->start_hitp);
	process(custom->max_hitp_allowed);
	process(custom->saving_allowed_first_level);
	process(custom->saving_allowed_last_level);
	process(custom->start_upside_down);
	process(custom->start_in_blind_mode);
	process(custom->copyprot_level);
	process(custom->drawn_tile_top_level_edge);
	process(custom->drawn_tile_left_level_edge);
	process(custom->level_edge_hit_tile);
	process(custom->allow_triggering_any_tile);
	process(custom->enable_wda_in_palace);
	process(custom->vga_palette);
	process(custom->first_level);
	process(custom->skip_title);
	process(custom->shift_L_allowed_until_level);
	process(custom->shift_L_reduced_minutes);
	process(custom->shift_L_reduced_ticks);
	process(custom->demo_hitp);
	process(custom->demo_end_room);
	process(custom->intro_music_level);
	process(custom->checkpoint_level);
	process(custom->checkpoint_respawn_dir);
	process(custom->checkpoint_respawn_room);
	process(custom->checkpoint_respawn_tilepos);
	process(custom->checkpoint_clear_tile_room);
	process(custom->checkpoint_clear_tile_col);
	process(custom->checkpoint_clear_tile_row);
	process(custom->skeleton_level);
	process(custom->skeleton_room);
	process(custom->skeleton_trigger_column_1);
	process(custom->skeleton_trigger_column_2);
	process(custom->skeleton_column);
	process(custom->skeleton_row);
	process(custom->skeleton_require_open_level_door);
	process(custom->skeleton_skill);
	process(custom->skeleton_reappear_room);
	process(custom->skeleton_reappear_x);
	process(custom->skeleton_reappear_row);
	process(custom->skeleton_reappear_dir);
	process(custom->mirror_level);
	process(custom->mirror_room);
	process(custom->mirror_column);
	process(custom->mirror_row);
	process(custom->mirror_tile);
	process(custom->show_mirror_image);
	process(custom->falling_exit_level);
	process(custom->falling_exit_room);
	process(custom->falling_entry_level);
	process(custom->falling_entry_room);
	process(custom->mouse_level);
	process(custom->mouse_room);
	process(custom->mouse_delay);
	process(custom->mouse_object);
	process(custom->mouse_start_x);
	process(custom->loose_tiles_level);
	process(custom->loose_tiles_room_1);
	process(custom->loose_tiles_room_2);
	process(custom->loose_tiles_first_tile);
	process(custom->loose_tiles_last_tile);
	process(custom->jaffar_victory_level);
	process(custom->jaffar_victory_flash_time);
	process(custom->hide_level_number_from_level);
	process(custom->level_13_level_number);
	process(custom->victory_stops_time_level);
	process(custom->win_level);
	process(custom->win_room);
	process(custom->loose_floor_delay);
}

void options_process_custom_per_level(SDL_RWops* rw, rw_process_func_type process_func) {
	process(custom->tbl_level_type);
	process(custom->tbl_level_color);
	process(custom->tbl_guard_type);
	process(custom->tbl_guard_hp);
	process(custom->tbl_cutscenes_by_index);
	process(custom->tbl_entry_pose);
	process(custom->tbl_seamless_exit);
}

#undef process

// struct for keeping track of both the normal and the replay options (which we want to easily switch between)
// (separately for each 'section', so adding future options becomes easy without messing up the format!)
typedef struct replay_options_section_type {
	dword data_size;
	byte replay_data[POP_MAX_OPTIONS_SIZE]; // binary representation of the options that are active during the replay
	byte stored_data[POP_MAX_OPTIONS_SIZE]; // normal options are restored from this, after the replay is finished
	process_options_section_func_type* section_func;
} replay_options_section_type;

replay_options_section_type replay_options_sections[] = {
	{.section_func = options_process_features},
	{.section_func = options_process_enhancements},
	{.section_func = options_process_fixes},
	{.section_func = options_process_custom_general},
	{.section_func = options_process_custom_per_level},
};

// output the current options to a memory buffer (e.g. to remember them before a replay is loaded)
size_t save_options_to_buffer(void* options_buffer, size_t max_size, process_options_section_func_type* process_section_func) {
	SDL_RWops* rw = SDL_RWFromMem(options_buffer, max_size);
	process_section_func(rw, process_rw_write);
	Sint64 section_size = SDL_RWtell(rw);
	if (section_size < 0) section_size = 0;
	SDL_RWclose(rw);
	return (size_t) section_size;
}

// restore the options from a memory buffer (e.g. reapply the original options after a replay is finished)
void load_options_from_buffer(void* options_buffer, size_t options_size, process_options_section_func_type* process_section_func) {
	SDL_RWops* rw = SDL_RWFromMem(options_buffer, options_size);
	process_section_func(rw, process_rw_read);
	SDL_RWclose(rw);
}


void init_record_replay() {
	if (!enable_replay) return;
	if (check_param("record")) {
		start_recording();
	}
	else if (need_start_replay || check_param("replay")) {
		start_replay();
	}
}

void replay_restore_level() {
	// Need to restore the savestate at the right time (just before the first room of the level is drawn).
	// Otherwise, for "on-the-fly" recordings, the screen will visibly "jump" to the replay savestate.
	// This only needs to happen at the very beginning of the replay (curr_tick == 0)
	if (curr_tick == 0) restore_savestate_from_buffer();
}

int process_to_buffer(void* data, size_t data_size) {
	if (savestate_offset + data_size > MAX_SAVESTATE_SIZE) {
		printf("Saving savestate to memory failed: buffer is overflowing!\n");
		return 0;
	}
	memcpy(savestate_buffer + savestate_offset, data, data_size);
	savestate_offset += data_size;
	return 1;
}

int process_load_from_buffer(void* data, size_t data_size) {
	// Prevent torches from being randomly colored when an older replay is loaded.
	if (savestate_offset >= savestate_size) return 0;

	memcpy(data, savestate_buffer + savestate_offset, data_size);
	savestate_offset += data_size;
	return 1;
}

int savestate_to_buffer() {
	int ok = 0;
	if (savestate_buffer == NULL)
		savestate_buffer = malloc(MAX_SAVESTATE_SIZE);
	if (savestate_buffer != NULL) {
		savestate_offset = 0;
		savestate_size = 0;
		ok = quick_process(process_to_buffer);
		savestate_size = savestate_offset;
	}
	return ok;
}

void reload_resources() {
	// the replay's levelset might use different sounds, so we need to free and reload sounds
	free_all_sounds();
	load_all_sounds();
	free_all_chtabs_from(id_chtab_0_sword);
	// chtabs 3 and higher will be freed/reloaded in load_lev_spr() (called by restore_room_after_quick_load())
	// However, chtabs 0-2 are usually not freed at all (they are loaded only once, in init_game_main())
	// So we should reload them manually (PRINCE.DAT and KID.DAT may still have been modified after all!)
	dat_type* dat = open_dat("PRINCE.DAT", 0);
	// PRINCE.DAT: sword
	chtab_addrs[id_chtab_0_sword] = load_sprites_from_file(700, 1<<2, 1);
	// PRINCE.DAT: flame, sword on floor, potion
	chtab_addrs[id_chtab_1_flameswordpotion] = load_sprites_from_file(150, 1<<3, 1);
	close_dat(dat);
	load_kid_sprite();  // reloads chtab 2
}

int restore_savestate_from_buffer() {
	int ok = 0;
	savestate_offset = 0;
	// This condition should be checked in process_load_from_buffer() instead of here.
	while (savestate_offset < savestate_size) {
		ok = quick_process(process_load_from_buffer);
	}
	reload_resources();
	restore_room_after_quick_load();
	return ok;
}

void start_recording() {
	curr_tick = 0;
	recording = 1; // further set-up is done in add_replay_move, on the first gameplay tick
}

void add_replay_move() {
	if (curr_tick == 0) {
		prandom(1); // make sure random_seed is initialized
		saved_random_seed = random_seed;
		seed_was_init = 1;
		savestate_to_buffer(); // create a savestate in memory
		display_text_bottom("RECORDING");
		text_time_total = 24;
		text_time_remaining = 24;
	}

	replay_move_type curr_move = {{0}};
	curr_move.x = control_x;
	curr_move.y = control_y;
	if (control_shift) curr_move.shift = 1;

	if (special_move)  {
		curr_move.special = special_move;
		special_move = 0;
	}

	moves[curr_tick] = curr_move.bits;

	++curr_tick;

	if (curr_tick >= MAX_REPLAY_DURATION) { // max replay length exceeded
		stop_recording();
	}
}

void stop_recording() {
	recording = 0;
	if (save_recorded_replay_dialog()) {
		display_text_bottom("REPLAY SAVED");
	} else {
		display_text_bottom("REPLAY CANCELED");
	}
	text_time_total = 24;
	text_time_remaining = 24;
}

void apply_replay_options() {
	// store the current options, so they can be restored later
	for (int i = 0; i < COUNT(replay_options_sections); ++i) {
		save_options_to_buffer(replay_options_sections[i].stored_data, POP_MAX_OPTIONS_SIZE, replay_options_sections[i].section_func);
	}

	// apply the options from the memory buffer (max. replay_options_size bytes will be read)
	for (int i = 0; i < COUNT(replay_options_sections); ++i) {
		load_options_from_buffer(replay_options_sections[i].replay_data, replay_options_sections[i].data_size, replay_options_sections[i].section_func);
	}

	fixes_saved = fixes_options_replay;
	turn_fixes_and_enhancements_on_off(use_fixes_and_enhancements);
	enable_replay = 1; // just to be safe...

	memcpy(stored_levelset_name, levelset_name, sizeof(levelset_name));
	memcpy(levelset_name, replay_levelset_name, sizeof(levelset_name));
	use_custom_levelset = (levelset_name[0] == '\0') ? 0 : 1;

	load_mod_options(); // Load resources from the correct places if there is a mod name in the replay file. This also prevents unwanted switching to PC Speaker mode.
	reload_resources();
}

void restore_normal_options() {
	// apply the stored options
	for (int i = 0; i < COUNT(replay_options_sections); ++i) {
		load_options_from_buffer(replay_options_sections[i].stored_data, POP_MAX_OPTIONS_SIZE, replay_options_sections[i].section_func);
	}

	start_level = -1; // may have been set to a different value by the replay

	memcpy(levelset_name, stored_levelset_name, sizeof(levelset_name));
	use_custom_levelset = (levelset_name[0] == '\0') ? 0 : 1;
}

static void print_remaining_time() {
	if (rem_min > 0) {
		printf("Remaining time: %d min, %d sec, %d ticks. ",
		       rem_min - 1, rem_tick / 12, rem_tick % 12);
	} else {
		printf("Elapsed time:   %d min, %d sec, %d ticks. ",
		       -(rem_min + 1), (719 - rem_tick) / 12, (719 - rem_tick) % 12);
	}
	printf("(rem_min=%d, rem_tick=%d)\n", rem_min, rem_tick);
}

void start_replay() {
	stop_sounds(); // Don't crash if the intro music is interrupted by Tab in PC Speaker mode.
	if (!enable_replay) return;
	need_start_replay = 0;
	if (!is_validate_mode) {
		list_replay_files();
		// If the replay was started from a file given in the command line, we don't care if there are no replay files in the replay folder.
		//if (num_replay_files == 0) return;
	}
	if (!load_replay()) return;
	// Set replaying before applying options, so the latter can display an appropriate error message if the referenced mod is missing.
	replaying = 1;
	apply_replay_options();
	curr_tick = 0;
}

void end_replay() {
	if (!is_validate_mode) {
		replaying = 0;
		skipping_replay = 0;
		restore_normal_options();
		start_game();
	} else {
		printf("\nReplay ended in level %d, room %d.\n", current_level, drawn_room);

		if (Kid.alive < 0)
			printf("Kid is alive.\n");
		else {
			if (text_time_total == 288 && text_time_remaining <= 1) {
				printf("Kid is dead. (Did not press button to continue.)\n");
			} else {
				printf("Kid is dead.\n");
			}
		}

		print_remaining_time();

		int minute_ticks = curr_tick % 720;
		printf("Play duration:  %d min, %d sec, %d ticks. (curr_tick=%d)\n\n",
		       curr_tick / 720, minute_ticks / 12, minute_ticks % 12, curr_tick);

		if (num_replay_ticks != curr_tick) {
			printf("WARNING: Play duration does not match replay length. (%d ticks)\n", num_replay_ticks);
		} else {
			printf("Play duration matches replay length. (%d ticks)\n", num_replay_ticks);
		}
		exit(0);
	}
}

void do_replay_move() {
	if (curr_tick == 0) {
		random_seed = saved_random_seed;
		seed_was_init = 1;

		if (is_validate_mode) {
			printf("Replay started in level %d, room %d.\n", current_level, drawn_room);
			print_remaining_time();
			skipping_replay = 1;
			replay_seek_target = replay_seek_2_end;
		}
	}
	if (curr_tick == num_replay_ticks) { // replay is finished
		end_replay();
		return;
	}
	if (current_level == next_level) {
		replay_move_type curr_move;
		curr_move.bits = moves[curr_tick];

		control_x = curr_move.x;
		control_y = curr_move.y;

		// Ignore Shift if the kid is dead: restart moves are hard-coded as a 'special move'.
		if (rem_min != 0 && Kid.alive > 6)
			control_shift = 0;
		else
			control_shift = (curr_move.shift) ? -1 : 0;

		if (curr_move.special == MOVE_RESTART_LEVEL) { // restart level
			stop_sounds();
			is_restart_level = 1;
		} else if (curr_move.special == MOVE_EFFECT_END) {
			stop_sounds();
			if (need_level1_music == 2) need_level1_music = 0;
			is_feather_fall = 0;
		}

//    if (curr_tick > 5 ) printf("rem_tick: %d\t curr_tick: %d\tlast 5 moves: %d, %d, %d, %d, %d\n", rem_tick, curr_tick,
//                               moves[curr_tick-4], moves[curr_tick-3], moves[curr_tick-2], moves[curr_tick-1], moves[curr_tick]);
		++curr_tick;
	}
}

int save_recorded_replay_dialog() {
	// prompt for replay filename
	rect_type rect;
	short bgcolor = color_8_darkgray;
	short color = color_15_brightwhite;
	current_target_surface = onscreen_surface_;
	method_1_blit_rect(offscreen_surface, onscreen_surface_, &copyprot_dialog->peel_rect, &copyprot_dialog->peel_rect, 0);
	draw_dialog_frame(copyprot_dialog);
	shrink2_rect(&rect, &copyprot_dialog->text_rect, 2, 1);
	show_text_with_color(&rect, 0, 0, "Save replay\nenter the filename...\n\n", color_15_brightwhite);
	clear_kbd_buf();

	rect_type text_rect;
	rect_type input_rect = {104,   64,  118,  256};
	offset4_rect_add(&text_rect, &input_rect, -2, 0, 2, 0);
	//peel_type* peel = read_peel_from_screen(&input_rect);
	draw_rect(&text_rect, bgcolor);
	current_target_surface = onscreen_surface_;
	need_full_redraw = 1; // lazy: instead of neatly restoring the dialog peel, just redraw the whole screen

	char input_filename[POP_MAX_PATH] = "";
	int input_length;
	do {
		input_length = input_str(&input_rect, input_filename, 64, "", 0, 0, color, bgcolor);
	} while (input_length == 0); // filename must be at least 1 character

	if (input_length < 0) {
		return 0;  // Escape was pressed -> discard the replay
	}

	char full_filename[POP_MAX_PATH] = "";
	snprintf_check(full_filename, sizeof(full_filename), "%s/%s.p1r", replays_folder, input_filename);

	// create the "replays" folder if it does not exist already
#if defined WIN32 || _WIN32 || WIN64 || _WIN64
	mkdir (replays_folder);
#else
	mkdir (replays_folder, 0700);
#endif

	// NOTE: We currently overwrite the replay file if it exists already. Maybe warn / ask for confirmation??

 return save_recorded_replay(full_filename);
}

int save_recorded_replay(const char* full_filename)
{
	replay_fp = fopen(full_filename, "wb");
	if (replay_fp != NULL) {
		fwrite(replay_magic_number, COUNT(replay_magic_number), 1, replay_fp); // magic number "P1R"
		fwrite(&replay_format_class, sizeof(replay_format_class), 1, replay_fp);
		putc(REPLAY_FORMAT_CURR_VERSION, replay_fp);
		putc(REPLAY_FORMAT_DEPRECATION_NUMBER, replay_fp);
		Sint64 seconds = time(NULL);
		fwrite(&seconds, sizeof(seconds), 1, replay_fp);
		// levelset_name
		putc(strnlen(levelset_name, UINT8_MAX), replay_fp); // length of the levelset name (is zero for original levels)
		fputs(levelset_name, replay_fp);
		// implementation name
		putc(strnlen(implementation_name, UINT8_MAX), replay_fp);
		fputs(implementation_name, replay_fp);
		// embed a savestate into the replay
		fwrite(&savestate_size, sizeof(savestate_size), 1, replay_fp);
		fwrite(savestate_buffer, savestate_size, 1, replay_fp);

		// save the options, organized per section
		byte temp_options[POP_MAX_OPTIONS_SIZE];
		for (int i = 0; i < COUNT(replay_options_sections); ++i) {
			dword section_size = save_options_to_buffer(temp_options, sizeof(temp_options), replay_options_sections[i].section_func);
			fwrite(&section_size, sizeof(section_size), 1, replay_fp);
			fwrite(temp_options, section_size, 1, replay_fp);
		}

		// save the rest of the replay data
		fwrite(&start_level, sizeof(start_level), 1, replay_fp);
		fwrite(&saved_random_seed, sizeof(saved_random_seed), 1, replay_fp);
		num_replay_ticks = curr_tick;
		fwrite(&num_replay_ticks, sizeof(num_replay_ticks), 1, replay_fp);
		fwrite(moves, num_replay_ticks, 1, replay_fp);
		fclose(replay_fp);
		replay_fp = NULL;
	}

	return 1;
}

byte open_next_replay_file() {
	if (next_replay_number > num_replay_files-1) {
		return 0; // reached the last replay file, return to title screen
	}
	current_replay_number = next_replay_number;
	++next_replay_number; // cycle
	open_replay_file(replay_list[current_replay_number].filename);
	if (replay_file_open) {
		return 1;
	}
	return 0;
}

void replay_cycle() {
	need_replay_cycle = 0;
	skipping_replay = 0;
	stop_sounds();
	if (current_replay_number == -1 /* opened .P1R file directly, so cycling is disabled */ ||
		!open_next_replay_file() ||
		!load_replay()
	) {
		// there is no replay to be cycled to after the current one --> restart the game
		replaying = 0;
		restore_normal_options();
		start_game();
		return;
	}
	apply_replay_options();
	restore_savestate_from_buffer();
	curr_tick = 0; // Do this after restoring the savestate, in case the savestate contained a non-zero curr_tick.
	show_level();
}

int load_replay() {
	if (!replay_file_open) {
		next_replay_number = 0;
		if (!open_next_replay_file()) {
			return 0;
		}
	}
	if (savestate_buffer == NULL)
		savestate_buffer = malloc(MAX_SAVESTATE_SIZE);
	if (replay_fp != NULL && savestate_buffer != NULL) {
		replay_header_type header = {0};
		char error_message[REPLAY_HEADER_ERROR_MESSAGE_MAX];
		int ok = read_replay_header(&header, replay_fp, error_message);
		if (!ok) {
			printf("Error loading replay: %s!\n", error_message);
			fclose(replay_fp);
			replay_fp = NULL;
			replay_file_open = 0;
			return 0;
		}

		memcpy(replay_levelset_name, header.levelset_name, sizeof(header.levelset_name));

		// load the savestate
		fread_check(&savestate_size, sizeof(savestate_size), 1, replay_fp);
		fread_check(savestate_buffer, savestate_size, 1, replay_fp);

		// load the replay options, organized per section
		for (int i = 0; i < COUNT(replay_options_sections); ++i) {
			dword section_size = 0;
			fread_check(&section_size, sizeof(section_size), 1, replay_fp);
			fread_check(replay_options_sections[i].replay_data, section_size, 1, replay_fp);
			replay_options_sections[i].data_size = section_size;
		}

		// load the rest of the replay data
		fread_check(&start_level, sizeof(start_level), 1, replay_fp);
		fread_check(&saved_random_seed, sizeof(saved_random_seed), 1, replay_fp);
		fread_check(&num_replay_ticks, sizeof(num_replay_ticks), 1, replay_fp);
		fread_check(moves, num_replay_ticks, 1, replay_fp);
		fclose(replay_fp);
		replay_fp = NULL;
		replay_file_open = 0;
		return 1; // success
	}
	return 0;
}

void key_press_while_recording(int* key_ptr) {
	int key = *key_ptr;
	switch(key) {
		case SDL_SCANCODE_A | WITH_CTRL:
			special_move = MOVE_RESTART_LEVEL;
			break;
		case SDL_SCANCODE_R | WITH_CTRL:
			save_recorded_replay_dialog();
			recording = 0;
		default:
			break;
	}
}

void key_press_while_replaying(int* key_ptr) {
	int key = *key_ptr;
	switch(key) {
		case 0:                                 // 'no key pressed'
			break;
		default:
			// cannot manually do most stuff during a replay, so cancel the pressed key...
			*key_ptr = 1; // don't set to zero (we would be unable to unpause a replay because all keys are ignored)
			              // (1 is not in use as a scancode, see https://wiki.libsdl.org/SDLScancodeLookup)
			break;
		// ...but these are allowable actions:
		case SDL_SCANCODE_ESCAPE:               // pause
		case SDL_SCANCODE_ESCAPE | WITH_SHIFT:
		case SDL_SCANCODE_BACKSPACE:            // menu
		case SDL_SCANCODE_SPACE:                // time
		case SDL_SCANCODE_S | WITH_CTRL:        // sound toggle
		case SDL_SCANCODE_V | WITH_CTRL:        // version
		case SDL_SCANCODE_C | WITH_CTRL:        // SDL version
		case SDL_SCANCODE_C:                    // room numbers
		case SDL_SCANCODE_C | WITH_SHIFT:
		case SDL_SCANCODE_I | WITH_SHIFT:       // invert
		case SDL_SCANCODE_B | WITH_SHIFT:       // blind
		case SDL_SCANCODE_T:                    // debug time
			break;
		case SDL_SCANCODE_R | WITH_CTRL:        // restart game
			replaying = 0;
			restore_normal_options();
			break;
		case SDL_SCANCODE_TAB:
			need_replay_cycle = 1;
			restore_normal_options();
			break;
		case SDL_SCANCODE_F:                    // skip forward to next room
			skipping_replay = 1;
			replay_seek_target = replay_seek_0_next_room;
			break;
		case SDL_SCANCODE_F | WITH_SHIFT:       // skip forward to start of next level
			skipping_replay = 1;
			replay_seek_target = replay_seek_1_next_level;
			break;
	}
}

#endif // USE_REPLAY