Xworld - Another World interpreter for Rockbox

Co-conspirators: Franklin Wei, Benjamin Brown

--------------------------------------------------------------------
This work is based on:
- Fabien Sanglard's "Fabother World" based on
- Piotr Padkowski's newRaw interpreter which was based on
- Gregory Montoir's reverse engineering of
- Eric Chahi's assembly code

--------------------------------------------------------------------
Progress:

* The plugin runs pretty nicely (with sound!) on most color targets
* Keymaps for color LCD targets are complete
* The manual entry is finished
* Grayscale/monochrome support is NOT PLANNED
  - the game looks horrible in grayscale! :p

--------------------------------------------------------------------
Notes:

* The original game strings were built-in to the executable, and
  were copyrighted and could not be used.
* This port ships with an alternate set of strings by default, but
  can load the "official" strings from a file at runtime.

--------------------------------------------------------------------
To be done (in descending order of importance):

* vertical stride compatibility                          <30% done>
* optimization                                           <10% done>

Change-Id: I3155b0d97c2ac470cb8a2040f40d4139ddcebfa5
Reviewed-on: http://gerrit.rockbox.org/1077
Reviewed-by: Michael Giacomelli <giac2000@hotmail.com>

1 files changed, 397 insertions, 0 deletions

diff --git a/apps/plugins/xworld/engine.c b/apps/plugins/xworld/engine.c
new file mode 100644
index 0000000..0d1c1bf
--- /dev/null
+++ b/apps/plugins/xworld/engine.c
@@ -0,0 +1,397 @@
+/***************************************************************************
+ *             __________               __   ___.
+ *   Open      \______   \ ____   ____ |  | _\_ |__   _______  ___
+ *   Source     |       _//  _ \_/ ___\|  |/ /| __ \ /  _ \  \/  /
+ *   Jukebox    |    |   (  <_> )  \___|    < | \_\ (  <_> > <  <
+ *   Firmware   |____|_  /\____/ \___  >__|_ \|___  /\____/__/\_ \
+ *                     \/            \/     \/    \/            \/
+ * $Id$
+ *
+ * Copyright (C) 2014 Franklin Wei, Benjamin Brown
+ * Copyright (C) 2004 Gregory Montoir
+ *
+ * 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 2
+ * of the License, or (at your option) any later version.
+ *
+ * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
+ * KIND, either express or implied.
+ *
+ ***************************************************************************/
+
+#include "plugin.h"
+#include "engine.h"
+#include "file.h"
+#include "serializer.h"
+#include "sys.h"
+#include "parts.h"
+#include "video_data.h"
+#include "video.h"
+
+void engine_create(struct Engine* e, struct System* stub, const char* dataDir, const char* saveDir)
+{
+    e->sys = stub;
+    e->sys->e = e;
+    e->_dataDir = dataDir;
+    e->_saveDir = saveDir;
+
+    mixer_create(&e->mixer, e->sys);
+
+    /* this needs to be here and not engine_init() to ensure that it is not called on a reset */
+    res_create(&e->res, &e->video, e->sys, dataDir);
+
+    res_allocMemBlock(&e->res);
+
+    video_create(&e->video, &e->res, e->sys);
+
+    player_create(&e->player, &e->mixer, &e->res, e->sys);
+
+    vm_create(&e->vm, &e->mixer, &e->res, &e->player, &e->video, e->sys);
+}
+
+void engine_run(struct Engine* e) {
+
+    while (!e->sys->input.quit) {
+
+        vm_checkThreadRequests(&e->vm);
+
+        vm_inp_updatePlayer(&e->vm);
+
+        engine_processInput(e);
+
+        vm_hostFrame(&e->vm);
+    }
+
+}
+
+/*
+ * this function loads the font in XWORLD_FONT_FILE into video_font
+ */
+
+/*
+ * the file format for the font file is like this:
+ * "XFNT" magic
+ * 8-bit version number
+ * <768 bytes data>
+ * sum of data, XOR'ed by version number repeated 4 times (32-bit)
+ */
+bool engine_loadFontFile(struct Engine* e)
+{
+    uint8_t *old_font = sys_get_buffer(e->sys, sizeof(video_font));
+    rb->memcpy(old_font, video_font, sizeof(video_font));
+
+    File f;
+    file_create(&f, false);
+    if(!file_open(&f, XWORLD_FONT_FILE, e->_dataDir, "rb"))
+    {
+        goto fail;
+    }
+
+    /* read header */
+    char header[5];
+    int ret = file_read(&f, header, sizeof(header));
+    if(ret != sizeof(header) ||
+            header[0] != 'X' ||
+            header[1] != 'F' ||
+            header[2] != 'N' ||
+            header[3] != 'T')
+    {
+        warning("Invalid font file signature, falling back to alternate font");
+        goto fail;
+    }
+
+    if(header[4] != XWORLD_FONT_VERSION)
+    {
+        warning("Font file version mismatch (have=%d, need=%d), falling back to alternate font", header[4], XWORLD_FONT_VERSION);
+        goto fail;
+    }
+
+    uint32_t sum = 0;
+    for(unsigned int i = 0;i<sizeof(video_font);++i)
+    {
+        sum += video_font[i] = file_readByte(&f);
+    }
+
+    uint32_t mask = (header[4] << 24) |
+                    (header[4] << 16) |
+                    (header[4] << 8 ) |
+                    (header[4] << 0 );
+    sum ^= mask;
+    uint32_t check = file_readUint32BE(&f);
+
+    if(check != sum)
+    {
+        warning("Bad font checksum, falling back to alternate font");
+        goto fail;
+    }
+
+    file_close(&f);
+    return true;
+
+fail:
+    file_close(&f);
+
+    memcpy(video_font, old_font, sizeof(video_font));
+    return false;
+}
+
+/*
+ * this function loads the string table in STRING_TABLE_FILE into
+ * video_stringsTableEng
+ */
+
+/*
+ * the file format for the string table is like this:
+ * "XWST" magic
+ * 8-bit version number
+ * 8-bit title length
+ * <title data (0-255 bytes, _NO NULL_)
+ * 16-bit number of string entries (currently limited to 255)
+ * entry format:
+   struct file_entry_t
+   {
+     uint16_t id;
+     uint16_t len; - length of str
+     char* str;    - NO NULL
+   }
+*/
+bool engine_loadStringTable(struct Engine* e)
+{
+    File f;
+    file_create(&f, false);
+    if(!file_open(&f, STRING_TABLE_FILE, e->_dataDir, "rb"))
+    {
+        /*
+         * this gives verbose warnings while loadFontFile doesn't because the font looks similar
+         * enough to pass for the "original", but the strings don't
+         */
+        warning("Unable to find string table, falling back to alternate strings");
+        goto fail;
+    }
+
+    /* read header */
+
+    char header[5];
+    int ret = file_read(&f, header, sizeof(header));
+    if(ret != sizeof(header) ||
+            header[0] != 'X' ||
+            header[1] != 'W' ||
+            header[2] != 'S' ||
+            header[3] != 'T')
+    {
+        warning("Invalid string table signature, falling back to alternate strings");
+        goto fail;
+    }
+
+    if(header[4] != STRING_TABLE_VERSION)
+    {
+        warning("String table version mismatch (have=%d, need=%d), falling back to alternate strings", header[4], STRING_TABLE_VERSION);
+        goto fail;
+    }
+
+    /* read title */
+
+    uint8_t title_length = file_readByte(&f);
+    char *title_buf;
+    if(title_length)
+    {
+        title_buf = sys_get_buffer(e->sys, (int32_t)title_length + 1); /* make room for the NULL */
+        ret = file_read(&f, title_buf, title_length);
+        if(ret != title_length)
+        {
+            warning("Title shorter than expected, falling back to alternate strings");
+            goto fail;
+        }
+    }
+    else
+    {
+        title_buf = "UNKNOWN";
+    }
+
+    /* read entries */
+
+    uint16_t num_entries = file_readUint16BE(&f);
+    for(unsigned int i = 0; i < num_entries && i < ARRAYLEN(video_stringsTableEng); ++i)
+    {
+        video_stringsTableEng[i].id = file_readUint16BE(&f);
+        uint16_t len                = file_readUint16BE(&f);
+
+        if(file_ioErr(&f))
+        {
+            warning("Unexpected EOF in while parsing entry %d, falling back to alternate strings", i);
+            goto fail;
+        }
+
+        video_stringsTableEng[i].str = sys_get_buffer(e->sys, (int32_t)len + 1);
+
+        ret = file_read(&f, video_stringsTableEng[i].str, len);
+        if(ret != len)
+        {
+            warning("Entry %d too short, falling back to alternate strings", i);
+            goto fail;
+        }
+    }
+
+    file_close(&f);
+    rb->splashf(HZ, "String table '%s' loaded", title_buf);
+    return true;
+fail:
+    file_close(&f);
+    return false;
+}
+
+void engine_init(struct Engine* e) {
+    sys_init(e->sys, "Out Of This World");
+
+    res_readEntries(&e->res);
+
+    engine_loadStringTable(e);
+
+    engine_loadFontFile(e);
+
+    video_init(&e->video);
+
+    vm_init(&e->vm);
+
+    mixer_init(&e->mixer);
+
+    player_init(&e->player);
+
+    /* Init virtual machine, legacy way */
+    /* vm_initForPart(&e->vm, GAME_PART_FIRST); // This game part is the protection screen */
+
+    /*  Try to cheat here. You can jump anywhere but the VM crashes afterward. */
+    /*  Starting somewhere is probably not enough, the variables and calls return are probably missing. */
+    /* vm_initForPart(&e->vm, GAME_PART2);  Skip protection screen and go directly to intro */
+    /* vm_initForPart(&e->vm, GAME_PART3);  CRASH */
+    /* vm_initForPart(&e->vm, GAME_PART4);  Start directly in jail but then crash */
+    /* vm->initForPart(&e->vm, GAME_PART5);   CRASH */
+    /* vm->initForPart(GAME_PART6);    Start in the battlechar but CRASH afteward */
+    /* vm->initForPart(GAME_PART7); CRASH */
+    /* vm->initForPart(GAME_PART8); CRASH */
+    /* vm->initForPart(GAME_PART9);  Green screen not doing anything */
+}
+
+void engine_finish(struct Engine* e) {
+    player_free(&e->player);
+    mixer_free(&e->mixer);
+    res_freeMemBlock(&e->res);
+}
+
+void engine_processInput(struct Engine* e) {
+    if (e->sys->input.load) {
+        engine_loadGameState(e, e->_stateSlot);
+        e->sys->input.load = false;
+    }
+    if (e->sys->input.save) {
+        engine_saveGameState(e, e->_stateSlot, "quicksave");
+        e->sys->input.save = false;
+    }
+    if (e->sys->input.fastMode) {
+        e->vm._fastMode = !&e->vm._fastMode;
+        e->sys->input.fastMode = false;
+    }
+    if (e->sys->input.stateSlot != 0) {
+        int8_t slot = e->_stateSlot + e->sys->input.stateSlot;
+        if (slot >= 0 && slot < MAX_SAVE_SLOTS) {
+            e->_stateSlot = slot;
+            debug(DBG_INFO, "Current game state slot is %d", e->_stateSlot);
+        }
+        e->sys->input.stateSlot = 0;
+    }
+}
+
+void engine_makeGameStateName(struct Engine* e, uint8_t slot, char *buf, int sz) {
+    (void) e;
+    rb->snprintf(buf, sz, "xworld_save.s%02d", slot);
+}
+
+void engine_saveGameState(struct Engine* e, uint8_t slot, const char *desc) {
+    char stateFile[20];
+    /* sizeof(char) is guaranteed to be 1 */
+    engine_makeGameStateName(e, slot, stateFile, sizeof(stateFile));
+    File f;
+    file_create(&f, false);
+    if (!file_open(&f, stateFile, e->_saveDir, "wb")) {
+        warning("Unable to save state file '%s'", stateFile);
+    } else {
+        /* header */
+        file_writeUint32BE(&f, SAVE_MAGIC);
+        file_writeUint16BE(&f, CUR_VER);
+        file_writeUint16BE(&f, 0);
+        char hdrdesc[32];
+        strncpy(hdrdesc, desc, sizeof(hdrdesc) - 1);
+        file_write(&f, hdrdesc, sizeof(hdrdesc));
+        /* contents */
+        struct Serializer s;
+        ser_create(&s, &f, SM_SAVE, e->res._memPtrStart, CUR_VER);
+        vm_saveOrLoad(&e->vm, &s);
+        res_saveOrLoad(&e->res, &s);
+        video_saveOrLoad(&e->video, &s);
+        player_saveOrLoad(&e->player, &s);
+        mixer_saveOrLoad(&e->mixer, &s);
+        if (file_ioErr(&f)) {
+            warning("I/O error when saving game state");
+        } else {
+            debug(DBG_INFO, "Saved state to slot %d", e->_stateSlot);
+        }
+    }
+    file_close(&f);
+}
+
+bool engine_loadGameState(struct Engine* e, uint8_t slot) {
+    char stateFile[20];
+    engine_makeGameStateName(e, slot, stateFile, 20);
+    File f;
+    file_create(&f, false);
+    if (!file_open(&f, stateFile, e->_saveDir, "rb")) {
+        debug(DBG_ENG, "Unable to open state file '%s'", stateFile);
+        goto fail;
+    } else {
+        uint32_t id = file_readUint32BE(&f);
+        if (id != SAVE_MAGIC) {
+            debug(DBG_ENG, "Bad savegame format");
+            goto fail;
+        } else {
+            /* mute */
+            player_stop(&e->player);
+            mixer_stopAll(&e->mixer);
+            /* header */
+            uint16_t ver = file_readUint16BE(&f);
+            file_readUint16BE(&f);
+            char hdrdesc[32];
+            file_read(&f, hdrdesc, sizeof(hdrdesc));
+            /* contents */
+            struct Serializer s;
+            ser_create(&s, &f, SM_LOAD, e->res._memPtrStart, ver);
+            vm_saveOrLoad(&e->vm, &s);
+            res_saveOrLoad(&e->res, &s);
+            video_saveOrLoad(&e->video, &s);
+            player_saveOrLoad(&e->player, &s);
+            mixer_saveOrLoad(&e->mixer, &s);
+        }
+        if (file_ioErr(&f)) {
+            debug(DBG_ENG, "I/O error when loading game state");
+            goto fail;
+        } else {
+            debug(DBG_INFO, "Loaded state from slot %d", e->_stateSlot);
+        }
+    }
+    file_close(&f);
+    return true;
+fail:
+    file_close(&f);
+    return false;
+}
+
+void engine_deleteGameState(struct Engine* e, uint8_t slot) {
+    char stateFile[20];
+    engine_makeGameStateName(e, slot, stateFile, 20);
+    file_remove(stateFile, e->_saveDir);
+}
+
+const char* engine_getDataDir(struct Engine* e)
+{
+    return e->_dataDir;
+}