2048: Cleanup

 - more whitespace to enhance readability
 - better/fixed/more comments ;)
 - some minor optimizations
 - general code cleanup

Change-Id: I2b5f69aba0f83f989abb2c636920646e4315583f

1 files changed, 391 insertions, 293 deletions

diff --git a/apps/plugins/2048.c b/apps/plugins/2048.c
index 7c2fd85668..15d3f41191 100644
--- a/apps/plugins/2048.c
+++ b/apps/plugins/2048.c
@@ -46,50 +46,49 @@
 #include "pluginbitmaps/_2048_tiles.h"
 #endif
 
-/* defines */
+/* some constants */
 
-#define ANIM_SLEEPTIME (HZ/20)
+static const int ANIM_SLEEPTIME = (HZ/20);
+static const int NUM_STARTING_TILES = 2;
+static const int VERT_SPACING = 4;
+static const int WHAT_FONT = FONT_UI;
+static const unsigned int WINNING_TILE = 2048;
+
+/* must use macros for these */
 #define GRID_SIZE 4
 #define HISCORES_FILE PLUGIN_GAMES_DATA_DIR "/2048.score"
+#define MIN_SPACE (BMPHEIGHT__2048_tiles * 0.134)
 #define NUM_SCORES 5
-#define NUM_STARTING_TILES 2
 #define RESUME_FILE PLUGIN_GAMES_DATA_DIR "/2048.save"
-#define WHAT_FONT FONT_UI
-#define SPACES (GRID_SIZE*GRID_SIZE)
-#define MIN_SPACE (BMPHEIGHT__2048_tiles*0.134) /* space between tiles */
-#define MAX_UNDOS 64
-#define VERT_SPACING 4
-#define WINNING_TILE 2048
+#define SPACES (GRID_SIZE * GRID_SIZE)
 
 /* screen-specific configuration */
 
-#if LCD_WIDTH<LCD_HEIGHT
-/* tall screens */
-#define TITLE_X 0
-#define TITLE_Y 0
-#define BASE_Y (BMPHEIGHT__2048_tiles*1.5)
-#define BASE_X (BMPHEIGHT__2048_tiles*.5-MIN_SPACE)
-#define SCORE_X 0
-#define SCORE_Y (max_numeral_height)
-#define BEST_SCORE_X 0
-#define BEST_SCORE_Y (2*max_numeral_height)
-#else
-/* wide screens or square screens*/
-#define TITLE_X 0
-#define TITLE_Y 0
-#define BASE_X (LCD_WIDTH-(GRID_SIZE*BMPHEIGHT__2048_tiles)-(((GRID_SIZE+1)*MIN_SPACE)))
-#define BASE_Y (BMPHEIGHT__2048_tiles*.5-MIN_SPACE)
-#define SCORE_X 0
-#define SCORE_Y (max_numeral_height)
-#define BEST_SCORE_X 0
-#define BEST_SCORE_Y (2*max_numeral_height)
-#endif /* LCD_WIDTH<LCD_HEIGHT */
-
-#define BACKGROUND_X (int)(BASE_X-MIN_SPACE)
-#define BACKGROUND_Y (int)(BASE_Y-MIN_SPACE)
+#if (LCD_WIDTH < LCD_HEIGHT) /* tall screens */
+#  define TITLE_X 0
+#  define TITLE_Y 0
+#  define BASE_Y (BMPHEIGHT__2048_tiles*1.5)
+#  define BASE_X (BMPHEIGHT__2048_tiles*.5-MIN_SPACE)
+#  define SCORE_X 0
+#  define SCORE_Y (max_numeral_height)
+#  define BEST_SCORE_X 0
+#  define BEST_SCORE_Y (2*max_numeral_height)
+#else /* wide or square screens */
+#  define TITLE_X 0
+#  define TITLE_Y 0
+#  define BASE_X (LCD_WIDTH-(GRID_SIZE*BMPHEIGHT__2048_tiles)-(((GRID_SIZE+1)*MIN_SPACE)))
+#  define BASE_Y (BMPHEIGHT__2048_tiles*.5-MIN_SPACE)
+#  define SCORE_X 0
+#  define SCORE_Y (max_numeral_height)
+#  define BEST_SCORE_X 0
+#  define BEST_SCORE_Y (2*max_numeral_height)
+#endif /* LCD_WIDTH < LCD_HEIGHT */
 
-/* key mappings */
+/* where to draw the background bitmap */
+static const int BACKGROUND_X = (BASE_X-MIN_SPACE);
+static const int BACKGROUND_Y = (BASE_Y-MIN_SPACE);
 
+/* key mappings */
 #define KEY_UP PLA_UP
 #define KEY_DOWN PLA_DOWN
 #define KEY_LEFT PLA_LEFT
@@ -97,48 +96,58 @@
 #define KEY_EXIT PLA_CANCEL
 #define KEY_UNDO PLA_SELECT
 
+/* notice how "color" is spelled :P */
+#ifdef HAVE_LCD_COLOR
+
 /* colors */
 
-#define BACKGROUND (LCD_RGBPACK(0xfa, 0xf8, 0xef))
-#define BOARD_BACKGROUND (LCD_RGBPACK(0xbb, 0xad, 0xa0))
-#define TEXT_COLOR (LCD_RGBPACK(0x77, 0x6e, 0x65))
+static const unsigned BACKGROUND = LCD_RGBPACK(0xfa, 0xf8, 0xef);
+static const unsigned BOARD_BACKGROUND = LCD_RGBPACK(0xbb, 0xad, 0xa0);
+static const unsigned TEXT_COLOR = LCD_RGBPACK(0x77, 0x6e, 0x65);
+
+#endif
 
+/* PLA data */
 static const struct button_mapping *plugin_contexts[] = { pla_main_ctx };
 
-/* game data */
+/*** game data structures ***/
+
 struct game_ctx_t {
-    int grid[GRID_SIZE][GRID_SIZE];
-    int score;
-    int cksum; /* sum of grid, XORed by score */
-    bool already_won;
-};
+    unsigned int grid[GRID_SIZE][GRID_SIZE]; /* 0 = empty */
+    unsigned int score;
+    unsigned int cksum;                      /* sum of grid, XORed by score */
+    bool already_won;                        /* has the player gotten 2048 yet? */
+} game_ctx;
+
+static struct game_ctx_t *ctx = &game_ctx;
 
-static struct game_ctx_t ctx_data;
-/* use a pointer to make save/load easier */
-static struct game_ctx_t *ctx=&ctx_data;
+/*** temporary data ***/
 
-/* temporary data */
 static bool merged_grid[GRID_SIZE][GRID_SIZE];
 static int old_grid[GRID_SIZE][GRID_SIZE];
-static int max_numeral_height=-1;
+
+static int max_numeral_height = -1;
+
 #if LCD_DEPTH <= 1
 static int max_numeral_width;
 #endif
-static bool loaded=false;
 
-/* first init_game will set this, when it is exceeded, it will be updated in the slide functions */
-static int best_score;
+static bool loaded = false; /* has a save been loaded? */
+
+/* the high score */
+static unsigned int best_score;
 
-static bool abnormal_exit=true;
+static bool abnormal_exit = true;
 static struct highscore highscores[NUM_SCORES];
 
-/* returns a random int between min and max */
+/***************************** UTILITY FUNCTIONS *****************************/
+
 static inline int rand_range(int min, int max)
 {
-    return rb->rand()%(max-min+1)+min;
+    return rb->rand() % (max-min + 1) + min;
 }
 
-/* prepares to exit */
+/* prepares for exit */
 static void cleanup(void)
 {
     backlight_use_settings();
@@ -148,66 +157,77 @@ static void cleanup(void)
 static inline int rand_2_or_4(void)
 {
     /* 1 in 10 chance of a four */
-    if(rb->rand()%10==0)
+    if(rb->rand() % 10 == 0)
         return 4;
     else
         return 2;
 }
 
-/* display the help text */
+/* displays the help text */
 static bool do_help(void)
 {
+
 #ifdef HAVE_LCD_COLOR
     rb->lcd_set_foreground(LCD_WHITE);
     rb->lcd_set_background(LCD_BLACK);
 #endif
+
     rb->lcd_setfont(FONT_UI);
-    char* help_text[]= {"2048", "", "Aim",
-                        "", "Join", "the", "numbers", "to", "get", "to", "the", "2048", "tile!", "", "",
-                        "How", "to", "Play", "",
-                        "", "Use", "the", "directional", "keys", "to", "move", "the", "tiles.", "When",
-                        "two", "tiles", "with", "the", "same", "number", "touch,", "they", "merge", "into", "one!"};
-    struct style_text style[]={
-        {0, TEXT_CENTER|TEXT_UNDERLINE},
-        {2, C_RED},
-        {15, C_RED}, {16, C_RED}, {17,C_RED},
+
+    static char* help_text[]= {"2048", "", "Aim",
+                               "", "Join", "the", "numbers", "to", "get", "to", "the", "2048", "tile!", "", "",
+                               "How", "to", "Play", "",
+                               "", "Use", "the", "directional", "keys", "to", "move", "the", "tiles.", "When",
+                               "two", "tiles", "with", "the", "same", "number", "touch,", "they", "merge", "into", "one!"};
+
+    struct style_text style[] = {
+        {0,  TEXT_CENTER | TEXT_UNDERLINE},
+        {2,  C_RED},
+        {15, C_RED},
+        {16, C_RED},
+        {17, C_RED},
         LAST_STYLE_ITEM
     };
-    return display_text(ARRAYLEN(help_text), help_text, style,NULL,true);
-}
 
-/*** the logic for sliding ***/
+    return display_text(ARRAYLEN(help_text), help_text, style, NULL, true);
+}
 
-/* this is the helper function that does the actual tile moving */
+/*** tile movement logic ***/
 
+/* this function performs the tile movement */
 static inline void slide_internal(int startx, int starty,
                                   int stopx, int stopy,
                                   int dx, int dy,
                                   int lookx, int looky,
                                   bool update_best)
 {
-    int best_score_before=best_score;
-    for(int y=starty;y!=stopy;y+=dy)
+    unsigned int best_score_old = best_score;
+
+    /* loop over the rows or columns, moving the tiles in the specified direction */
+    for(int y = starty; y != stopy; y += dy)
     {
-        for(int x=startx;x!=stopx;x+=dx)
+        for(int x = startx; x != stopx; x += dx)
         {
-            if(ctx->grid[x+lookx][y+looky]==ctx->grid[x][y] && ctx->grid[x][y] && !merged_grid[x+lookx][y+looky] && !merged_grid[x][y]) /* Slide into */
+            if(ctx->grid[x + lookx][y + looky] == ctx->grid[x][y] &&
+               ctx->grid[x][y]                                    &&
+               !merged_grid[x + lookx][y + looky]                 &&
+               !merged_grid[x][y]) /* merge these two tiles */
             {
                 /* Each merged tile cannot be merged again */
-                merged_grid[x+lookx][y+looky]=true;
-                ctx->grid[x+lookx][y+looky]=2*ctx->grid[x][y];
-                ctx->score+=ctx->grid[x+lookx][y+looky];
-                ctx->grid[x][y]=0;
+                merged_grid[x + lookx][y + looky] = true;
+                ctx->grid[x + lookx][y + looky] = 2 * ctx->grid[x][y];
+                ctx->score += ctx->grid[x + lookx][y + looky];
+                ctx->grid[x][y] = 0;
             }
-            else if(ctx->grid[x+lookx][y+looky]==0) /* Empty! */
+            else if(ctx->grid[x + lookx][y + looky] == 0) /* Empty! */
             {
-                ctx->grid[x+lookx][y+looky]=ctx->grid[x][y];
-                ctx->grid[x][y]=0;
+                ctx->grid[x + lookx][y + looky] = ctx->grid[x][y];
+                ctx->grid[x][y] = 0;
             }
         }
     }
-    if(ctx->score>best_score_before && update_best)
-        best_score=ctx->score;
+    if(ctx->score > best_score_old && update_best)
+        best_score = ctx->score;
 }
 
 /* these functions move each tile 1 space in the direction specified via calls to slide_internal */
@@ -227,6 +247,7 @@ static void up(bool update_best)
                    0, -1, /* lookahead values */
                    update_best);
 }
+
 /* Down
    0 v v v v
    1 v v v v
@@ -242,6 +263,7 @@ static void down(bool update_best)
                    0, 1,
                    update_best);
 }
+
 /* Left
    0   < < <
    1   < < <
@@ -257,6 +279,7 @@ static void left(bool update_best)
                    -1, 0,
                    update_best);
 }
+
 /* Right
    0 > > >
    1 > > >
@@ -273,31 +296,44 @@ static void right(bool update_best)
                    update_best);
 }
 
-/* slightly modified version of base 2 log, returns 1 when given zero, and log2(n)+1 for anything else */
+/* copies old_grid to ctx->grid */
+static inline void RESTORE_GRID(void)
+{
+    memcpy(&ctx->grid, &old_grid, sizeof(ctx->grid));
+}
 
+/* slightly modified base 2 logarithm, returns 1 when given zero, and log2(n) + 1 for anything else */
 static inline int ilog2(int n)
 {
-    if(n==0)
+    if(n == 0)
         return 1;
-    int log=0;
-    while(n>1)
+    int log = 0;
+    while(n > 1)
     {
-        n>>=1;
+        n >>= 1;
         ++log;
     }
-    return log+1;
+    return log + 1;
 }
+
+/* low-depth displays resort to text drawing, see the #else case below */
+
 #if LCD_DEPTH > 1
+
+/* draws game screen + updates LCD */
 static void draw(void)
 {
 #ifdef HAVE_LCD_COLOR
     rb->lcd_set_background(BACKGROUND);
 #endif
+
     rb->lcd_clear_display();
 
     /* draw the background */
 
-    rb->lcd_bitmap(_2048_background, BACKGROUND_X, BACKGROUND_Y, BMPWIDTH__2048_background, BMPWIDTH__2048_background);
+    rb->lcd_bitmap(_2048_background,
+                   BACKGROUND_X, BACKGROUND_Y,
+                   BMPWIDTH__2048_background, BMPWIDTH__2048_background);
 
     /*
       grey_gray_bitmap(_2048_background, BACKGROUND_X, BACKGROUND_Y, BMPWIDTH__2048_background, BMPHEIGHT__2048_background);
@@ -305,290 +341,316 @@ static void draw(void)
 
     /* draw the grid */
 
-    for(int y=0;y<GRID_SIZE;++y)
+    for(int y = 0; y < GRID_SIZE; ++y)
     {
-        for(int x=0;x<GRID_SIZE;++x)
+        for(int x = 0; x < GRID_SIZE; ++x)
         {
-            rb->lcd_bitmap_part(_2048_tiles, /* source */
-                                BMPWIDTH__2048_tiles-BMPHEIGHT__2048_tiles*ilog2(ctx->grid[x][y]), 0, /* source upper left corner */
-                                STRIDE(SCREEN_MAIN, BMPWIDTH__2048_tiles, BMPHEIGHT__2048_tiles), /* stride */
-                                (BMPHEIGHT__2048_tiles+MIN_SPACE)*x+BASE_X, (BMPHEIGHT__2048_tiles+MIN_SPACE)*y+BASE_Y, /* dest upper-left corner */
-                                BMPHEIGHT__2048_tiles, BMPHEIGHT__2048_tiles); /* size of the cut section */
+            rb->lcd_bitmap_part(_2048_tiles,                                                                                        /* source */
+                                BMPWIDTH__2048_tiles - BMPHEIGHT__2048_tiles * ilog2(ctx->grid[x][y]), 0,                           /* source upper left corner */
+                                STRIDE(SCREEN_MAIN, BMPWIDTH__2048_tiles, BMPHEIGHT__2048_tiles),                                   /* stride */
+                                (BMPHEIGHT__2048_tiles + MIN_SPACE) * x + BASE_X, (BMPHEIGHT__2048_tiles + MIN_SPACE) * y + BASE_Y, /* dest upper-left corner */
+                                BMPHEIGHT__2048_tiles, BMPHEIGHT__2048_tiles);                                                      /* size of the cut section */
         }
     }
+
     /* draw the title */
     char buf[32];
+
 #ifdef HAVE_LCD_COLOR
     rb->lcd_set_foreground(TEXT_COLOR);
 #endif
-    rb->snprintf(buf, 31, "%d", WINNING_TILE);
 
-    /* check if the title will go into the grid */
+    rb->snprintf(buf, sizeof(buf), "%d", WINNING_TILE);
+
+    /* check if the title will overlap the grid */
     int w, h;
     rb->lcd_setfont(FONT_UI);
     rb->font_getstringsize(buf, &w, &h, FONT_UI);
-    bool draw_title=true;
-    if(w+TITLE_X>=BACKGROUND_X && h+TITLE_Y>=BACKGROUND_Y)
+    bool draw_title = true;
+    if(w + TITLE_X >= BACKGROUND_X && h + TITLE_Y >= BACKGROUND_Y)
     {
         /* if it goes into the grid, use the system font, which should be smaller */
         rb->lcd_setfont(FONT_SYSFIXED);
         rb->font_getstringsize(buf, &w, &h, FONT_SYSFIXED);
-        if(w+TITLE_X>=BACKGROUND_X && h+TITLE_Y>=BACKGROUND_Y)
+        if(w + TITLE_X >= BACKGROUND_X && h + TITLE_Y >= BACKGROUND_Y)
         {
             /* title can't fit, don't draw it */
-            draw_title=false;
-            h=0;
+            draw_title = false;
+            h = 0;
         }
     }
+
     if(draw_title)
         rb->lcd_putsxy(TITLE_X, TITLE_Y, buf);
-    int score_y=TITLE_Y+h+VERT_SPACING;
+
+    int score_y = TITLE_Y + h + VERT_SPACING;
+
     /* draw the score */
-    rb->snprintf(buf, 31, "Score: %d", ctx->score);
+    rb->snprintf(buf, sizeof(buf), "Score: %d", ctx->score);
+
 #ifdef HAVE_LCD_COLOR
     rb->lcd_set_foreground(LCD_WHITE);
     rb->lcd_set_background(BOARD_BACKGROUND);
 #endif
+
     rb->lcd_setfont(FONT_UI);
     rb->font_getstringsize(buf, &w, &h, FONT_UI);
-    if(w+SCORE_X>=BACKGROUND_X && h+SCORE_Y>=BACKGROUND_Y)
+
+    /* try making the score fit */
+    if(w + SCORE_X >= BACKGROUND_X && h + SCORE_Y >= BACKGROUND_Y)
     {
         /* score overflows */
         /* first see if it fits with Score: and FONT_SYSFIXED */
         rb->lcd_setfont(FONT_SYSFIXED);
         rb->font_getstringsize(buf, &w, &h, FONT_SYSFIXED);
-        if(w+SCORE_X < BACKGROUND_X)
+        if(w + SCORE_X < BACKGROUND_X)
             /* it fits, go and draw it */
             goto draw_lbl;
 
         /* now try with S: and FONT_UI */
-        rb->snprintf(buf, 31, "S: %d", ctx->score);
+        rb->snprintf(buf, sizeof(buf), "S: %d", ctx->score);
         rb->font_getstringsize(buf, &w, &h, FONT_UI);
         rb->lcd_setfont(FONT_UI);
-        if(w+SCORE_X<BACKGROUND_X)
+        if(w + SCORE_X < BACKGROUND_X)
             goto draw_lbl;
 
         /* now try with S: and FONT_SYSFIXED */
-        rb->snprintf(buf, 31, "S: %d", ctx->score);
+        rb->snprintf(buf, sizeof(buf), "S: %d", ctx->score);
         rb->font_getstringsize(buf, &w, &h, FONT_SYSFIXED);
         rb->lcd_setfont(FONT_SYSFIXED);
-        if(w+SCORE_X<BACKGROUND_X)
+        if(w + SCORE_X < BACKGROUND_X)
             goto draw_lbl;
 
         /* then try without Score: and FONT_UI */
-        rb->snprintf(buf, 31, "%d", ctx->score);
+        rb->snprintf(buf, sizeof(buf), "%d", ctx->score);
         rb->font_getstringsize(buf, &w, &h, FONT_UI);
         rb->lcd_setfont(FONT_UI);
-        if(w+SCORE_X<BACKGROUND_X)
+        if(w + SCORE_X < BACKGROUND_X)
             goto draw_lbl;
 
         /* as a last resort, don't use Score: and use the system font */
-        rb->snprintf(buf, 31, "%d", ctx->score);
+        rb->snprintf(buf, sizeof(buf), "%d", ctx->score);
         rb->font_getstringsize(buf, &w, &h, FONT_SYSFIXED);
         rb->lcd_setfont(FONT_SYSFIXED);
-        if(w+SCORE_X<BACKGROUND_X)
+        if(w + SCORE_X < BACKGROUND_X)
             goto draw_lbl;
         else
             goto skip_draw_score;
     }
+
 draw_lbl:
     rb->lcd_putsxy(SCORE_X, score_y, buf);
-    score_y+=h+VERT_SPACING;
+    score_y += h + VERT_SPACING;
+
     /* draw the best score */
 skip_draw_score:
-    rb->snprintf(buf, 31, "Best: %d", best_score);
+    rb->snprintf(buf, sizeof(buf), "Best: %d", best_score);
+
 #ifdef HAVE_LCD_COLOR
     rb->lcd_set_foreground(LCD_WHITE);
     rb->lcd_set_background(BOARD_BACKGROUND);
 #endif
+
     rb->lcd_setfont(FONT_UI);
     rb->font_getstringsize(buf, &w, &h, FONT_UI);
-    if(w+BEST_SCORE_X>=BACKGROUND_X && h+BEST_SCORE_Y>=BACKGROUND_Y)
+    if(w + BEST_SCORE_X >= BACKGROUND_X && h + BEST_SCORE_Y >= BACKGROUND_Y)
     {
         /* score overflows */
         /* first see if it fits with Score: and FONT_SYSFIXED */
         rb->lcd_setfont(FONT_SYSFIXED);
         rb->font_getstringsize(buf, &w, &h, FONT_SYSFIXED);
-        if(w+BEST_SCORE_X < BACKGROUND_X)
+        if(w + BEST_SCORE_X < BACKGROUND_X)
             /* it fits, go and draw it */
             goto draw_best;
 
         /* now try with S: and FONT_UI */
-        rb->snprintf(buf, 31, "B: %d", best_score);
+        rb->snprintf(buf, sizeof(buf), "B: %d", best_score);
         rb->font_getstringsize(buf, &w, &h, FONT_UI);
         rb->lcd_setfont(FONT_UI);
-        if(w+BEST_SCORE_X<BACKGROUND_X)
+        if(w + BEST_SCORE_X < BACKGROUND_X)
             goto draw_best;
 
         /* now try with S: and FONT_SYSFIXED */
-        rb->snprintf(buf, 31, "B: %d", best_score);
+        rb->snprintf(buf, sizeof(buf), "B: %d", best_score);
         rb->font_getstringsize(buf, &w, &h, FONT_SYSFIXED);
         rb->lcd_setfont(FONT_SYSFIXED);
-        if(w+BEST_SCORE_X<BACKGROUND_X)
+        if(w + BEST_SCORE_X < BACKGROUND_X)
             goto draw_best;
 
         /* then try without Score: and FONT_UI */
-        rb->snprintf(buf, 31, "%d", best_score);
+        rb->snprintf(buf, sizeof(buf), "%d", best_score);
         rb->font_getstringsize(buf, &w, &h, FONT_UI);
         rb->lcd_setfont(FONT_UI);
-        if(w+BEST_SCORE_X<BACKGROUND_X)
+        if(w + BEST_SCORE_X < BACKGROUND_X)
             goto draw_best;
 
         /* as a last resort, don't use Score: and use the system font */
-        rb->snprintf(buf, 31, "%d", best_score);
+        rb->snprintf(buf, sizeof(buf), "%d", best_score);
         rb->font_getstringsize(buf, &w, &h, FONT_SYSFIXED);
         rb->lcd_setfont(FONT_SYSFIXED);
-        if(w+BEST_SCORE_X<BACKGROUND_X)
+        if(w + BEST_SCORE_X < BACKGROUND_X)
             goto draw_best;
         else
             goto skip_draw_best;
     }
 draw_best:
     rb->lcd_putsxy(BEST_SCORE_X, score_y, buf);
+
 skip_draw_best:
     rb->lcd_update();
-    /* revert the font back */
+
+    /* revert the font */
     rb->lcd_setfont(WHAT_FONT);
 }
+
 #else /* LCD_DEPTH > 1 */
+
 /* 1-bit display :( */
-/* bitmaps are unreadable with these screens, so just resort to text */
+/* bitmaps are unreadable on these screens, so just resort to text-based drawing */
 static void draw(void)
 {
     rb->lcd_clear_display();
+
     /* Draw the grid */
     /* find the biggest tile */
-    int biggest_tile=-1;
-    for(int x=0;x<GRID_SIZE;++x)
+    unsigned int biggest_tile = 0;
+    for(int x = 0; x < GRID_SIZE; ++x)
     {
-        for(int y=0;y<GRID_SIZE;++y)
-            if(ctx->grid[x][y]>biggest_tile)
-                biggest_tile=ctx->grid[x][y];
+        for(int y = 0; y < GRID_SIZE; ++y)
+            if(ctx->grid[x][y] > biggest_tile)
+                biggest_tile = ctx->grid[x][y];
     }
-    char str[32];
-    rb->snprintf(str, 31,"%d", biggest_tile);
-    int biggest_tile_width=rb->strlen(str)*rb->font_get_width(rb->font_get(WHAT_FONT), '0')+MIN_SPACE;
-    for(int y=0;y<GRID_SIZE;++y)
+
+    char buf[32];
+
+    rb->snprintf(buf, 32, "%d", biggest_tile);
+
+    int biggest_tile_width = rb->strlen(buf) * rb->font_get_width(rb->font_get(WHAT_FONT), '0') + MIN_SPACE;
+
+    for(int y = 0; y < GRID_SIZE; ++y)
     {
-        for(int x=0;x<GRID_SIZE;++x)
+        for(int x = 0; x < GRID_SIZE; ++x)
         {
             if(ctx->grid[x][y])
             {
-                if(ctx->grid[x][y]>biggest_tile)
-                    biggest_tile=ctx->grid[x][y];
-                rb->snprintf(str,31,"%d", ctx->grid[x][y]);
-                rb->lcd_putsxy(biggest_tile_width*x,y*max_numeral_height+max_numeral_height,str);
+                if(ctx->grid[x][y] > biggest_tile)
+                    biggest_tile = ctx->grid[x][y];
+                rb->snprintf(buf, 32, "%d", ctx->grid[x][y]);
+                rb->lcd_putsxy(biggest_tile_width * x, y * max_numeral_height + max_numeral_height, buf);
             }
         }
     }
+
     /* Now draw the score, and the game title */
-    rb->snprintf(str, 31, "Score: %d", ctx->score);
-    int str_width, str_height;
-    rb->font_getstringsize(str, &str_width, &str_height, WHAT_FONT);
-    int score_leftmost=LCD_WIDTH-str_width-1;
+    rb->snprintf(buf, 32, "Score: %d", ctx->score);
+    int buf_width, buf_height;
+    rb->font_getstringsize(buf, &buf_width, &buf_height, WHAT_FONT);
+
+    int score_leftmost = LCD_WIDTH - buf_width - 1;
     /* Check if there is enough space to display "Score: ", otherwise, only display the score */
-    if(score_leftmost>=0)
-        rb->lcd_putsxy(score_leftmost,0,str);
+    if(score_leftmost >= 0)
+        rb->lcd_putsxy(score_leftmost, 0, buf);
     else
-        rb->lcd_putsxy(score_leftmost,0,str+rb->strlen("Score: "));
-    /* Reuse the same string for the title */
+        rb->lcd_putsxy(score_leftmost, 0, buf + rb->strlen("Score: "));
+
+    rb->snprintf(buf, 32, "%d", WINNING_TILE);
+    rb->font_getstringsize(buf, &buf_width, &buf_height, WHAT_FONT);
+    if(buf_width < score_leftmost)
+        rb->lcd_putsxy(0, 0, buf);
 
-    rb->snprintf(str, 31, "%d", WINNING_TILE);
-    rb->font_getstringsize(str, &str_width, &str_height, WHAT_FONT);
-    if(str_width<score_leftmost)
-        rb->lcd_putsxy(0,0,str);
     rb->lcd_update();
 }
+
 #endif /* LCD_DEPTH > 1 */
+
 /* place a 2 or 4 in a random empty space */
 static void place_random(void)
 {
-    int xpos[SPACES],ypos[SPACES];
-    int back=0;
+    int xpos[SPACES], ypos[SPACES];
+    int back = 0;
     /* get the indexes of empty spaces */
-    for(int y=0;y<GRID_SIZE;++y)
-        for(int x=0;x<GRID_SIZE;++x)
+    for(int y = 0; y < GRID_SIZE; ++y)
+        for(int x = 0; x < GRID_SIZE; ++x)
         {
             if(!ctx->grid[x][y])
             {
-                xpos[back]=x;
-                ypos[back]=y;
-                ++back;
+                xpos[back] = x;
+                ypos[back++] = y;
             }
         }
+
     if(!back)
         /* no empty spaces */
         return;
-    int idx=rand_range(0,back-1);
-    ctx->grid[xpos[idx]][ypos[idx]]=rand_2_or_4();
-}
 
-/* copies old_grid to ctx->grid */
-static void restore_old_grid(void)
-{
-    memcpy(&ctx->grid, &old_grid, sizeof(int)*SPACES);
+    int idx = rand_range(0, back - 1);
+    ctx->grid[ xpos[idx] ][ ypos[idx] ] = rand_2_or_4();
 }
 
 /* checks for a win or loss */
 static bool check_gameover(void)
 {
     /* first, check for a loss */
-    int oldscore=ctx->score;
-    bool have_legal_move=false;
-    memset(&merged_grid,0,SPACES*sizeof(bool));
+    int oldscore = ctx->score;
+    bool have_legal_move = false;
+
+    memset(&merged_grid, 0, SPACES * sizeof(bool));
     up(false);
-    if(memcmp(&old_grid, &ctx->grid, sizeof(int)*SPACES))
+    if(memcmp(&old_grid, &ctx->grid, sizeof(ctx->grid)))
     {
-        restore_old_grid();
-        ctx->score=oldscore;
-        have_legal_move=true;
+        RESTORE_GRID();
+        ctx->score = oldscore;
+        have_legal_move = true;
     }
-    restore_old_grid();
-    memset(&merged_grid,0,SPACES*sizeof(bool));
+    RESTORE_GRID();
+
+    memset(&merged_grid, 0, SPACES * sizeof(bool));
     down(false);
-    if(memcmp(&old_grid, &ctx->grid, sizeof(int)*SPACES))
+    if(memcmp(&old_grid, &ctx->grid, sizeof(ctx->grid)))
     {
-        restore_old_grid();
-        ctx->score=oldscore;
-        have_legal_move=true;
+        RESTORE_GRID();
+        ctx->score = oldscore;
+        have_legal_move = true;
     }
-    restore_old_grid();
-    memset(&merged_grid,0,SPACES*sizeof(bool));
+    RESTORE_GRID();
+
+    memset(&merged_grid, 0, SPACES * sizeof(bool));
     left(false);
-    if(memcmp(&old_grid, &ctx->grid, sizeof(int)*SPACES))
+    if(memcmp(&old_grid, &ctx->grid, sizeof(ctx->grid)))
     {
-        restore_old_grid();
-        ctx->score=oldscore;
-        have_legal_move=true;
+        RESTORE_GRID();
+        ctx->score = oldscore;
+        have_legal_move = true;
     }
-    restore_old_grid();
-    memset(&merged_grid,0,SPACES*sizeof(bool));
+    RESTORE_GRID();
+
+    memset(&merged_grid, 0, SPACES * sizeof(bool));
     right(false);
-    if(memcmp(&old_grid, &ctx->grid, sizeof(int)*SPACES))
+    if(memcmp(&old_grid, &ctx->grid, sizeof(ctx->grid)))
     {
-        restore_old_grid();
-        ctx->score=oldscore;
-        have_legal_move=true;
+        RESTORE_GRID();
+        ctx->score = oldscore;
+        have_legal_move = true;
     }
-    ctx->score=oldscore;
+    ctx->score = oldscore;
     if(!have_legal_move)
     {
         /* no more legal moves */
-        draw(); /* Shame the player :) */
+        draw(); /* Shame the player */
         rb->splash(HZ*2, "Game Over!");
         return true;
     }
-    for(int y=0;y<GRID_SIZE;++y)
+
+    for(int y = 0;y < GRID_SIZE; ++y)
     {
-        for(int x=0;x<GRID_SIZE;++x)
+        for(int x = 0; x < GRID_SIZE; ++x)
         {
-            if(ctx->grid[x][y]==WINNING_TILE && !ctx->already_won)
+            if(ctx->grid[x][y] == WINNING_TILE && !ctx->already_won)
             {
                 /* Let the user see the tile in its full glory... */
                 draw();
-                ctx->already_won=true;
+                ctx->already_won = true;
                 rb->splash(HZ*2,"You win!");
-                /* don't let the user quit here :) */
             }
         }
     }
@@ -602,38 +664,43 @@ static void load_hs(void)
     if(rb->file_exists(HISCORES_FILE))
         highscore_load(HISCORES_FILE, highscores, NUM_SCORES);
     else
-        memset(highscores, 0, sizeof(struct highscore)*NUM_SCORES);
+        memset(highscores, 0, sizeof(struct highscore) * NUM_SCORES);
 }
 
 /* initialize the data structures */
 static void init_game(bool newgame)
 {
-    best_score=highscores[0].score;
+    best_score = highscores[0].score;
     if(loaded && ctx->score > best_score)
-        best_score=ctx->score;
+        best_score = ctx->score;
+
     if(newgame)
     {
         /* initialize the game context */
-        memset(ctx->grid, 0, sizeof(int)*SPACES);
-        for(int i=0;i<NUM_STARTING_TILES;++i)
+        memset(ctx->grid, 0, sizeof(ctx->grid));
+        for(int i = 0; i < NUM_STARTING_TILES; ++i)
         {
             place_random();
         }
-        ctx->score=0;
-        ctx->already_won=false;
+        ctx->score = 0;
+        ctx->already_won = false;
     }
+
     /* using the menu resets the font */
     /* set it again here */
+
     rb->lcd_setfont(WHAT_FONT);
+
     /* Now calculate font sizes */
     /* Now get the height of the font */
-    rb->font_getstringsize("0123456789", NULL, &max_numeral_height,WHAT_FONT);
-    max_numeral_height+=VERT_SPACING;
+    rb->font_getstringsize("0123456789", NULL, &max_numeral_height, WHAT_FONT);
+    max_numeral_height += VERT_SPACING;
+
 #if LCD_DEPTH <= 1
-    max_numeral_width=rb->font_get_width(rb->font_get(WHAT_FONT), '0');
+    max_numeral_width = rb->font_get_width(rb->font_get(WHAT_FONT), '0');
 #endif
+
     backlight_ignore_timeout();
-    rb->lcd_clear_display();
     draw();
 }
 
@@ -641,17 +708,22 @@ static void init_game(bool newgame)
 static void save_game(void)
 {
     rb->splash(0, "Saving...");
-    int fd=rb->open(RESUME_FILE,O_WRONLY|O_CREAT, 0666);
-    if(fd<0)
+    int fd = rb->open(RESUME_FILE, O_WRONLY|O_CREAT, 0666);
+    if(fd < 0)
     {
         return;
     }
-    ctx->cksum=0;
-    for(int x=0;x<GRID_SIZE;++x)
-        for(int y=0;y<GRID_SIZE;++y)
-            ctx->cksum+=ctx->grid[x][y];
-    ctx->cksum^=ctx->score;
-    rb->write(fd, ctx,sizeof(struct game_ctx_t));
+
+    /* calculate checksum */
+    ctx->cksum = 0;
+
+    for(int x = 0; x < GRID_SIZE; ++x)
+        for(int y = 0; y < GRID_SIZE; ++y)
+            ctx->cksum += ctx->grid[x][y];
+
+    ctx->cksum ^= ctx->score;
+
+    rb->write(fd, ctx, sizeof(struct game_ctx_t));
     rb->close(fd);
     rb->lcd_update();
 }
@@ -659,59 +731,67 @@ static void save_game(void)
 /* loads a saved game, returns true on success */
 static bool load_game(void)
 {
-    int success=0;
-    int fd=rb->open(RESUME_FILE, O_RDONLY);
-    if(fd<0)
+    int success = 0;
+    int fd = rb->open(RESUME_FILE, O_RDONLY);
+    if(fd < 0)
     {
         rb->remove(RESUME_FILE);
         return false;
     }
-    int numread=rb->read(fd, ctx, sizeof(struct game_ctx_t));
-    int calc=0;
-    for(int x=0;x<GRID_SIZE;++x)
-        for(int y=0;y<GRID_SIZE;++y)
-            calc+=ctx->grid[x][y];
-    calc^=ctx->score;
-    if(numread==sizeof(struct game_ctx_t) && calc==ctx->cksum)
+
+    int numread = rb->read(fd, ctx, sizeof(struct game_ctx_t));
+
+    /* verify checksum */
+    unsigned int calc = 0;
+    for(int x = 0; x < GRID_SIZE; ++x)
+        for(int y = 0; y < GRID_SIZE; ++y)
+            calc += ctx->grid[x][y];
+
+    calc ^= ctx->score;
+
+    if(numread == sizeof(struct game_ctx_t) && calc == ctx->cksum)
         ++success;
+
     rb->close(fd);
     rb->remove(RESUME_FILE);
-    return (success==1);
+
+    return (success > 0);
 }
 
 /* update the highscores with ctx->score */
 static void hs_check_update(bool noshow)
 {
     /* first, find the biggest tile to show as the level */
-    int biggest=0;
-    for(int x=0;x<GRID_SIZE;++x)
+    unsigned int biggest = 0;
+    for(int x = 0; x < GRID_SIZE; ++x)
     {
-        for(int y=0;y<GRID_SIZE;++y)
+        for(int y = 0; y < GRID_SIZE; ++y)
         {
-            if(ctx->grid[x][y]>biggest)
-                biggest=ctx->grid[x][y];
+            if(ctx->grid[x][y] > biggest)
+                biggest = ctx->grid[x][y];
         }
     }
-    int hs_idx=highscore_update(ctx->score,biggest, "", highscores,NUM_SCORES);
+
+    int hs_idx = highscore_update(ctx->score,biggest, "", highscores,NUM_SCORES);
     if(!noshow)
     {
         /* show the scores if there is a new high score */
-        if(hs_idx>=0)
+        if(hs_idx >= 0)
         {
-            rb->splashf(HZ*2,"New High Score: %d", ctx->score);
+            rb->splashf(HZ*2, "New High Score: %d", ctx->score);
             rb->lcd_clear_display();
-            highscore_show(hs_idx,highscores,NUM_SCORES,true);
+            highscore_show(hs_idx, highscores, NUM_SCORES, true);
         }
     }
-    highscore_save(HISCORES_FILE,highscores,NUM_SCORES);
+    highscore_save(HISCORES_FILE, highscores, NUM_SCORES);
 }
 
 /* asks the user if they wish to quit */
 static bool confirm_quit(void)
 {
-    const struct text_message prompt={(const char*[]){"Are you sure?", "This will clear your current game."}, 2};
-    enum yesno_res response=rb->gui_syncyesno_run(&prompt, NULL, NULL);
-    if(response==YESNO_NO)
+    const struct text_message prompt = { (const char*[]) {"Are you sure?", "This will clear your current game."}, 2};
+    enum yesno_res response = rb->gui_syncyesno_run(&prompt, NULL, NULL);
+    if(response == YESNO_NO)
         return false;
     else
         return true;
@@ -720,7 +800,7 @@ static bool confirm_quit(void)
 /* show the pause menu */
 static int do_2048_pause_menu(void)
 {
-    int sel=0;
+    int sel = 0;
     MENUITEM_STRINGLIST(menu,"2048 Menu", NULL,
                         "Resume Game",
                         "Start New Game",
@@ -729,7 +809,7 @@ static int do_2048_pause_menu(void)
                         "Help",
                         "Quit without Saving",
                         "Quit");
-    bool quit=false;
+    bool quit = false;
     while(!quit)
     {
         switch(rb->do_menu(&menu, &sel, NULL, false))
@@ -748,7 +828,7 @@ static int do_2048_pause_menu(void)
             }
         }
         case 2:
-            highscore_show(-1,highscores, NUM_SCORES, true);
+            highscore_show(-1, highscores, NUM_SCORES, true);
             break;
         case 3:
             playback_control(NULL);
@@ -782,80 +862,85 @@ static void exit_handler(void)
 #endif
     return;
 }
+
 static bool check_hs;
+
 /* main game loop */
 static enum plugin_status do_game(bool newgame)
 {
     init_game(newgame);
-    rb_atexit(&exit_handler);
-    int made_move=0;
+    rb_atexit(exit_handler);
+    int made_move = 0;
     while(1)
     {
 #ifdef HAVE_ADJUSTABLE_CPU_FREQ
         rb->cpu_boost(false); /* Save battery when idling */
 #endif
         /* Wait for a button press */
-        int button=pluginlib_getaction(-1, plugin_contexts, ARRAYLEN(plugin_contexts));
-        made_move=0;
-        memset(&merged_grid,0,SPACES*sizeof(bool));
+        int button = pluginlib_getaction(-1, plugin_contexts, ARRAYLEN(plugin_contexts));
+        made_move = 0;
+
+        memset(&merged_grid, 0, SPACES*sizeof(bool));
         memcpy(&old_grid, &ctx->grid, sizeof(int)*SPACES);
-        int grid_before_anim_step[GRID_SIZE][GRID_SIZE];
+
+        unsigned int grid_before_anim_step[GRID_SIZE][GRID_SIZE];
+
 #ifdef HAVE_ADJUSTABLE_CPU_FREQ
         rb->cpu_boost(true); /* doing work now... */
 #endif
         switch(button)
         {
         case KEY_UP:
-            for(int i=0;i<GRID_SIZE-1;++i)
+            for(int i = 0; i < GRID_SIZE - 1; ++i)
             {
-                memcpy(grid_before_anim_step, ctx->grid, sizeof(int)*SPACES);
+                memcpy(grid_before_anim_step, ctx->grid, sizeof(ctx->grid));
                 up(true);
-                if(memcmp(grid_before_anim_step, ctx->grid, sizeof(int)*SPACES))
+                if(memcmp(grid_before_anim_step, ctx->grid, sizeof(ctx->grid)))
                 {
                     rb->sleep(ANIM_SLEEPTIME);
                     draw();
                 }
             }
-            made_move=1;
+            made_move = 1;
             break;
         case KEY_DOWN:
-            for(int i=0;i<GRID_SIZE-1;++i)
+            for(int i = 0; i < GRID_SIZE - 1; ++i)
             {
-                memcpy(grid_before_anim_step, ctx->grid, sizeof(int)*SPACES);
+                memcpy(grid_before_anim_step, ctx->grid, sizeof(ctx->grid));
                 down(true);
-                if(memcmp(grid_before_anim_step, ctx->grid, sizeof(int)*SPACES))
+                if(memcmp(grid_before_anim_step, ctx->grid, sizeof(ctx->grid)))
                 {
                     rb->sleep(ANIM_SLEEPTIME);
                     draw();
                 }
             }
-            made_move=1;
+            made_move = 1;
             break;
         case KEY_LEFT:
-            for(int i=0;i<GRID_SIZE-1;++i)
+            for(int i = 0; i < GRID_SIZE - 1; ++i)
             {
-                memcpy(grid_before_anim_step, ctx->grid, sizeof(int)*SPACES);
+                memcpy(grid_before_anim_step, ctx->grid, sizeof(ctx->grid));
                 left(true);
-                if(memcmp(grid_before_anim_step, ctx->grid, sizeof(int)*SPACES))
+                if(memcmp(grid_before_anim_step, ctx->grid, sizeof(ctx->grid)))
                 {
                     rb->sleep(ANIM_SLEEPTIME);
                     draw();
                 }
             }
-            made_move=1;
+            made_move = 1;
             break;
         case KEY_RIGHT:
-            for(int i=0;i<GRID_SIZE-1;++i)
+            for(int i = 0; i < GRID_SIZE - 1; ++i)
             {
-                memcpy(grid_before_anim_step, ctx->grid, sizeof(int)*SPACES);
+                memcpy(grid_before_anim_step, ctx->grid, sizeof(ctx->grid));
                 right(true);
-                if(memcmp(grid_before_anim_step, ctx->grid, sizeof(int)*SPACES))
+                if(memcmp(grid_before_anim_step, ctx->grid, sizeof(ctx->grid)))
                 {
                     rb->sleep(ANIM_SLEEPTIME);
                     draw();
                 }
             }
-            made_move=1;
+            made_move = 1;
             break;
         case KEY_EXIT:
             switch(do_2048_pause_menu())
@@ -864,33 +949,33 @@ static enum plugin_status do_game(bool newgame)
                 break;
             case 1: /* new game */
                 init_game(true);
-                made_move=1;
+                made_move = 1;
                 continue;
-                break;
             case 2: /* quit without saving */
-                check_hs=true;
+                check_hs = true;
                 rb->remove(RESUME_FILE);
                 return PLUGIN_ERROR;
             case 3: /* save and quit */
-                check_hs=false;
+                check_hs = false;
                 save_game();
                 return PLUGIN_ERROR;
             }
             break;
         default:
         {
-            exit_on_usb(button); /* handles poweroff and USB events */
+            exit_on_usb(button); /* handle poweroff and USB events */
             break;
         }
         }
+
         if(made_move)
         {
-            /* Check if we actually moved, then add random */
-            if(memcmp(&old_grid, ctx->grid, sizeof(int)*SPACES))
+            /* Check if any tiles moved, then add random */
+            if(memcmp(&old_grid, ctx->grid, sizeof(ctx->grid)))
             {
                 place_random();
             }
-            memcpy(&old_grid, ctx->grid, sizeof(int)*SPACES);
+            memcpy(&old_grid, ctx->grid, sizeof(ctx->grid));
             if(check_gameover())
                 return PLUGIN_OK;
             draw();
@@ -906,8 +991,8 @@ static enum plugin_status do_game(bool newgame)
 /* used to hide resume option when there is no save */
 static int mainmenu_cb(int action, const struct menu_item_ex *this_item)
 {
-    int idx=((intptr_t)this_item);
-    if(action==ACTION_REQUEST_MENUITEM && !loaded && (idx==0 || idx==5))
+    int idx = ((intptr_t)this_item);
+    if(action == ACTION_REQUEST_MENUITEM && !loaded && (idx == 0 || idx == 5))
         return ACTION_EXIT_MENUITEM;
     return action;
 }
@@ -915,29 +1000,37 @@ static int mainmenu_cb(int action, const struct menu_item_ex *this_item)
 /* show the main menu */
 static enum plugin_status do_2048_menu(void)
 {
-    int sel=0;
-    loaded=load_game();
-    MENUITEM_STRINGLIST(menu,"2048 Menu", mainmenu_cb, "Resume Game", "Start New Game","High Scores","Playback Control", "Help", "Quit without Saving", "Quit");
-    bool quit=false;
+    int sel = 0;
+    loaded = load_game();
+    MENUITEM_STRINGLIST(menu,
+                        "2048 Menu",
+                        mainmenu_cb,
+                        "Resume Game",
+                        "Start New Game",
+                        "High Scores",
+                        "Playback Control",
+                        "Help",
+                        "Quit without Saving",
+                        "Quit");
+    bool quit = false;
     while(!quit)
     {
-        int item;
-        switch(item=rb->do_menu(&menu,&sel,NULL,false))
+        switch(rb->do_menu(&menu, &sel, NULL, false))
         {
         case 0: /* Start new game or resume a game */
         case 1:
         {
-            if(item==1 && loaded)
+            if(sel == 1 && loaded)
             {
                 if(!confirm_quit())
                     break;
             }
-            enum plugin_status ret=do_game(item==1);
+            enum plugin_status ret = do_game(sel == 1);
             switch(ret)
             {
             case PLUGIN_OK:
             {
-                loaded=false;
+                loaded = false;
                 rb->remove(RESUME_FILE);
                 hs_check_update(false);
                 break;
@@ -956,7 +1049,7 @@ static enum plugin_status do_2048_menu(void)
             break;
         }
         case 2:
-            highscore_show(-1,highscores, NUM_SCORES, true);
+            highscore_show(-1, highscores, NUM_SCORES, true);
             break;
         case 3:
             playback_control(NULL);
@@ -977,6 +1070,8 @@ static enum plugin_status do_2048_menu(void)
     }
     return PLUGIN_OK;
 }
+
+/* plugin entry point */
 enum plugin_status plugin_start(const void* param)
 {
     (void)param;
@@ -985,9 +1080,12 @@ enum plugin_status plugin_start(const void* param)
     rb->lcd_setfont(WHAT_FONT);
 
     /* now start the game menu */
-    enum plugin_status ret=do_2048_menu();
-    highscore_save(HISCORES_FILE,highscores,NUM_SCORES);
+    enum plugin_status ret = do_2048_menu();
+
+    highscore_save(HISCORES_FILE, highscores, NUM_SCORES);
     cleanup();
-    abnormal_exit=false;
+
+    abnormal_exit = false;
+
     return ret;
 }