Avoid drawing the whole screen on each frame

This allows supporting 386DX "just about" (there will be flickering).

15 files changed, 136 insertions, 207 deletions

diff --git a/README.md b/README.md
index 710073d..04599dc 100644
--- a/README.md
+++ b/README.md
@@ -8,7 +8,7 @@ Running the game:
 
 - MS/DOS or compatible
 - A DOS Protected Mode Interface, e.g. [CWSDPMI](http://sandmann.dotster.com/cwsdpmi/)
-- 386DX (with FPU) or better with VGA
+- Plays on a 386DX with VGA, but a 486 or better is highly recommended
 - At least 4MB of RAM
 - Sound Blaster (or no sound)
 
diff --git a/data/stage.json b/data/stage.json
index 5758a5b..6d8b6a4 100644
--- a/data/stage.json
+++ b/data/stage.json
@@ -44,34 +44,6 @@
                 }, 
                 {
                  "height":16,
-                 "id":2,
-                 "name":"Bat",
-                 "rotation":0,
-                 "type":"",
-                 "visible":true,
-                 "width":16,
-                 "x":240,
-                 "y":32
-                }, 
-                {
-                 "height":16,
-                 "id":3,
-                 "name":"Snake",
-                 "properties":[
-                        {
-                         "name":"dir",
-                         "type":"string",
-                         "value":"left"
-                        }],
-                 "rotation":0,
-                 "type":"",
-                 "visible":true,
-                 "width":16,
-                 "x":288,
-                 "y":128
-                }, 
-                {
-                 "height":16,
                  "id":4,
                  "name":"Bat",
                  "rotation":0,
@@ -94,17 +66,6 @@
                 }, 
                 {
                  "height":16,
-                 "id":10,
-                 "name":"Pickaxe",
-                 "rotation":0,
-                 "type":"",
-                 "visible":true,
-                 "width":16,
-                 "x":56,
-                 "y":104
-                }, 
-                {
-                 "height":16,
                  "id":13,
                  "name":"Pickaxe",
                  "rotation":0,
@@ -116,17 +77,6 @@
                 }, 
                 {
                  "height":16,
-                 "id":11,
-                 "name":"Bonus",
-                 "rotation":0,
-                 "type":"",
-                 "visible":true,
-                 "width":16,
-                 "x":80,
-                 "y":104
-                }, 
-                {
-                 "height":16,
                  "id":12,
                  "name":"Bonus",
                  "rotation":0,
@@ -155,23 +105,6 @@
                 }, 
                 {
                  "height":16,
-                 "id":7,
-                 "name":"Bat",
-                 "properties":[
-                        {
-                         "name":"dir",
-                         "type":"string",
-                         "value":"left"
-                        }],
-                 "rotation":0,
-                 "type":"",
-                 "visible":true,
-                 "width":16,
-                 "x":32,
-                 "y":40
-                }, 
-                {
-                 "height":16,
                  "id":8,
                  "name":"Snake",
                  "rotation":0,
diff --git a/src/Makefile b/src/Makefile
index 4870f10..be1b0e1 100644
--- a/src/Makefile
+++ b/src/Makefile
@@ -4,7 +4,7 @@ endif
 
 BIN	:= ../game.exe
 CC	:= i586-pc-msdosdjgpp-gcc
-CFLAGS	:= -I. -I$(LIBMIKMOD_BASE)/include -g -c -Wall -Werror -pedantic -O2 -fomit-frame-pointer -ffast-math -march=i386 -DDEBUG
+CFLAGS	:= -I. -I$(LIBMIKMOD_BASE)/include -c -Wall -Werror -pedantic -O3 -fomit-frame-pointer -ffast-math -march=i386 -DDEBUG
 LDFLAGS := -s -L$(LIBMIKMOD_BASE)/dos
 LIBS	:= -lmikmod
 
diff --git a/src/entities.c b/src/entities.c
index df8fb4e..e24c119 100644
--- a/src/entities.c
+++ b/src/entities.c
@@ -8,7 +8,7 @@
 
 #include "effect.h"
 
-#define MAX_ENTITY 32
+#define MAX_ENTITY 16
 
 static Entity entities[MAX_ENTITY];
 static uint8_t last;
@@ -44,31 +44,36 @@ void entities_update()
 
     for (uint8_t i = 0; i < last; i++, e++)
         if (e->used)
+        {
+            e->ox = e->x;
+            e->oy = e->y;
             e->update(e);
+        }
 }
 
-void entities_erase()
+void entities_draw()
 {
-    Entity *e = entities + last - 1;
+    Rect dst = { 0, 0, 16, 16 };
+    Entity *e = entities;
 
-    for (uint8_t i = 0; i < last; i++, e--)
-        if (e->used)
+    for (uint8_t i = 0; i < last; i++, e++)
+        if (e->erase)
         {
-            Rect dst = { e->x, e->y + MAP_OFFS_Y, 16, 16 };
-            blit(e->bg, &dst);
+            dst.x = e->ox;
+            dst.y = e->oy + MAP_OFFS_Y;
+            blit_copy(&dst);
+            e->erase = 0;
         }
-}
 
-void entities_draw()
-{
-    Entity *e = entities;
+    e = entities;
 
     for (uint8_t i = 0; i < last; i++, e++)
         if (e->used)
         {
-            Rect dst = { e->x, e->y + MAP_OFFS_Y, 16, 16 };
-            read_buffer(e->bg, &dst);
+            dst.x = e->x;
+            dst.y = e->y + MAP_OFFS_Y;
             blitrc(binary_sprites_start, &e->frames[e->dir * 4 + e->frame], &dst);
+            e->erase = 1;
         }
 }
 
diff --git a/src/entities.h b/src/entities.h
index 99424de..169e582 100644
--- a/src/entities.h
+++ b/src/entities.h
@@ -11,13 +11,15 @@ typedef struct entity_s
     uint8_t used;
     uint16_t x;
     uint16_t y;
+    uint8_t erase;
+    uint16_t ox;
+    uint16_t oy;
     uint8_t dir;
     uint8_t frame;
     uint8_t delay;
     uint8_t gravity;
     uint8_t flags;
     uint16_t counter;
-    uint8_t bg[16 * 16];
     /* expected to be 2 directions per 4 frames max; 8 Rect */
     const Rect *frames;
     void (*update)(struct entity_s *e);
@@ -28,10 +30,7 @@ void entities_init();
 Entity *entities_new();
 
 void entities_update();
-
-void entities_erase();
 void entities_draw();
-
 void entities_warp_out_all();
 
 #endif /* _ENTITIES_H */
diff --git a/src/game.c b/src/game.c
index ba6ee85..67f7739 100644
--- a/src/game.c
+++ b/src/game.c
@@ -91,7 +91,7 @@ static void hud_render()
         sprintf(b, "%02d", time);
         put_text(172, 4, b, time > 10 || stageclear ? 1 : 15);
         if (!gameover && !stageclear && time <= 10)
-            sound_queue_efx(EFX_TIME);
+            sound_play_efx(EFX_TIME);
     }
 
     if (hud & HUD_STAGE)
@@ -105,6 +105,8 @@ static void hud_render()
 
 static void run_gameover()
 {
+    wait_vsync();
+
     blit_erase(0);
 
     /* restore the HUD after erasing the screen */
@@ -113,19 +115,14 @@ static void run_gameover()
 
     put_text(124, 90, "GAME OVER", 1);
 
-    wait_vsync();
-    blit_update();
-
     /* wait some time */
     wait_frames(255);
 }
 
 static void run_stageclear()
 {
-    put_text(116, 100, "STAGE CLEAR", 1);
-
     wait_vsync();
-    blit_update();
+    put_text(116, 100, "STAGE CLEAR", 1);
 
     /* wait some time */
     wait_frames(96);
@@ -135,23 +132,24 @@ static void run_stageclear()
         add_score(25);
         time--;
         hud |= HUD_TIME;
-        sound_queue_efx(EFX_GOLD);
-        hud_render();
 
         wait_frames(4);
-        blit_update();
-        sound_play_queue();
+
+        wait_vsync();
+        hud_render();
+        sound_play_efx(EFX_GOLD);
     }
 
     /* wait some time */
     wait_frames(64);
 
+    wait_vsync();
     blit_erase(0);
+
     /* restore the HUD after erasing the screen */
     hud = HUD_ALL;
-    hud_render();
     wait_vsync();
-    blit_update();
+    hud_render();
 
     wait_frames(32);
 }
@@ -173,25 +171,30 @@ next_stage:
 
     tmonster = NULL;
 
+    blit_target(TARGET_BUFFER);
     blit_erase(0);
 
     map_init(binary_stage_start);
 
-    /* render the scene with the READY? text */
     map_render();
-    entities_draw();
-    player_draw();
     hud_render();
-    put_text(136, 100, "READY?", 1);
 
     wait_vsync();
-    blit_update();
+    blit_copy_all();
+
+    blit_target(TARGET_SCREEN);
+    put_text(136, 100, "READY?", 1);
+
+    entities_draw();
+    player_draw();
 
     /* wait some time */
     wait_frames(96);
 
     /* erase the READY? text */
-    map_render();
+    wait_vsync();
+    blit_copy_all();
+
     entities_draw();
     player_draw();
 
@@ -226,10 +229,6 @@ next_stage:
         if (pause)
             continue;
 
-        /* erase first the last we draw */
-        player_erase();
-        entities_erase();
-
         if (map_is_complete())
         {
             if (!stageclear)
@@ -237,7 +236,7 @@ next_stage:
                 timer_stop();
                 tmonster = NULL;
                 entities_warp_out_all();
-                sound_queue_efx(EFX_WARP);
+                sound_play_efx(EFX_WARP);
 
                 stageclear = STAGECLEAR_DELAY;
             }
@@ -271,13 +270,12 @@ next_stage:
 
         entities_update();
 
+        wait_vsync();
+
+        player_erase();
         entities_draw();
         player_draw();
 
-        wait_vsync();
-        blit_update();
-        sound_play_queue();
-
         if (gameover)
         {
             gameover--;
diff --git a/src/map.c b/src/map.c
index e5e67d1..5599ae9 100644
--- a/src/map.c
+++ b/src/map.c
@@ -74,8 +74,8 @@ void map_init(const uint8_t map[])
         }
 #endif
 
-        e->x = ent[1] * MAP_TILE_W;
-        e->y = ent[2] * MAP_TILE_H;
+        e->ox = e->x = ent[1] * MAP_TILE_W;
+        e->oy = e->y = ent[2] * MAP_TILE_H;
         e->dir = ent[3] & 1;
 
         init[*ent - 1](e);
@@ -98,15 +98,8 @@ void map_render()
             src.y = (t / MAP_TILESET_COLS) * MAP_TILE_H;
 
             blitrc(binary_tiles_start, &src, &dst);
-        }
-
-    for (uint8_t y = 0; y < MAP_H; y++)
-        for (uint8_t x = 0; x < MAP_W; x++)
-        {
-            dst.x = x * MAP_TILE_W;
-            dst.y = y * MAP_TILE_H + MAP_OFFS_Y;
 
-            uint8_t t = gold[x + y * MAP_W];
+            t = gold[x + y * MAP_W];
 
             /* not gold, skip! */
             if (t == 0xff)
@@ -150,7 +143,9 @@ uint8_t map_update_gold(uint16_t x, uint16_t y)
         src.x = (t % MAP_TILESET_COLS) * MAP_TILE_W;
         src.y = (t / MAP_TILESET_COLS) * MAP_TILE_H;
 
+        blit_target(TARGET_BUFFER);
         blitrc(binary_tiles_start, &src, &dst);
+        blit_target(TARGET_SCREEN);
 
         total_gold--;
         return 1;
diff --git a/src/menu.c b/src/menu.c
index 4eeed8e..3d4456e 100644
--- a/src/menu.c
+++ b/src/menu.c
@@ -63,7 +63,7 @@ static void render_cast()
         put_text(dst.x + 16 + 8, dst.y + 6, names[i], i + 2);
 
         wait_vsync();
-        blit_update();
+        blit_copy_all();
 
         wait_frames(32);
 
@@ -77,6 +77,7 @@ uint8_t run_menu()
     uint8_t cast = 0;
     uint8_t wait;
 
+    blit_target(TARGET_BUFFER);
     while (1)
     {
         if (keys[KEY_ESC])
@@ -100,7 +101,7 @@ uint8_t run_menu()
             }
 
             wait_vsync();
-            blit_update();
+            blit_copy_all();
         }
 
         /* if is not cast, we do the "blink" effect */
@@ -113,8 +114,9 @@ uint8_t run_menu()
                     wait = 0;
 
                 put_text(84, 110, "PRESS SPACE TO PLAY", wait ? 0 : 1);
+
                 wait_vsync();
-                blit_update();
+                blit_copy_all();
             }
         }
 
diff --git a/src/pickup.c b/src/pickup.c
index 91e44b2..7036891 100644
--- a/src/pickup.c
+++ b/src/pickup.c
@@ -136,7 +136,7 @@ void pickup_wait_update(Entity *e)
     if (e->counter-- == 0)
     {
         e->update = pickup_in_update;
-        sound_queue_efx(EFX_WARP);
+        sound_play_efx(EFX_WARP);
     }
 }
 
@@ -174,7 +174,7 @@ void pickup_update(Entity *e)
     if (e->counter++ == MAX_TTL)
     {
         effect_out_init(e);
-        sound_queue_efx(EFX_WARP);
+        sound_play_efx(EFX_WARP);
         return;
     }
 
@@ -208,6 +208,6 @@ void pickup_update(Entity *e)
                 break;
         }
         e->used = 0;
-        sound_queue_efx(EFX_PICKUP);
+        sound_play_efx(EFX_PICKUP);
     }
 }
diff --git a/src/player.c b/src/player.c
index 8c1765a..399dacf 100644
--- a/src/player.c
+++ b/src/player.c
@@ -24,20 +24,18 @@
 
 #define IS_NOT_GOING_UP(x) (gravity == GRAVITY_OFF || (x)>=GRAVITY_DOWN)
 
-static uint16_t x, y;
+static uint16_t x, y, ox, oy, erase;
 static uint8_t dir, frame, delay, gravity, jump, momentum;
 
 static uint16_t respawn_x, respawn_y;
 static uint8_t respawn_dir;
 
-static uint8_t invuln, dying;
+static uint8_t invuln, dying, dead;
 
 const uint8_t gravity_seq[GRAVITY_SEQ_LEN] = {
     6, 4, 4, 2, 2, 2, 2, 1, 1, 1, 0, 0, 0, 0, 0, 0, 1, 1, 1, 2, 2, 2, 2, 4
 };
 
-static uint8_t bg[256];
-
 static const Rect frames[2][6] =
 {
     {
@@ -77,9 +75,11 @@ void player_init(uint16_t start_x, uint8_t start_y, uint8_t start_dir)
     momentum = 0;
     invuln = 0;
     dying = 0;
+    dead = 0;
+    erase = 0;
 
-    respawn_x = x = start_x;
-    respawn_y = y = start_y;
+    respawn_x = ox = x = start_x;
+    respawn_y = oy = y = start_y;
     gravity = GRAVITY_OFF;
 }
 
@@ -97,17 +97,20 @@ static void player_dying()
                 /* exit screen */
                 if (y == MAP_H * MAP_TILE_H - 16)
                 {
+                    /* oh, well */
+                    player_erase();
+
                     /* if there are lifes left, respawn */
                     if (dec_lives())
                     {
                         player_init(respawn_x, respawn_y, respawn_dir);
                         invuln = INVULN_TIME;
                     }
+                    else
+                        dead = 1;
 
                     /* stop falling */
                     gravity = GRAVITY_OFF;
-                    /* don't draw the player; XXX: magic number */
-                    invuln = 4;
                     return;
                 }
                 y++;
@@ -131,6 +134,9 @@ void player_update()
 {
     uint8_t moved = 0;
 
+    ox = x;
+    oy = y;
+
     if (dying)
     {
         player_dying();
@@ -160,7 +166,7 @@ void player_update()
             momentum = 0;
             frame = FRAME_JUMPING;
             gravity = GRAVITY_UP;
-            sound_queue_efx(EFX_JUMP);
+            sound_play_efx(EFX_JUMP);
         }
     }
     else
@@ -273,26 +279,30 @@ void player_update()
     if (map_update_gold(x + (dir == DIR_LEFT ? 7 : 8), y + 15))
     {
         add_score(10);
-        sound_queue_efx(EFX_GOLD);
+        sound_play_efx(EFX_GOLD);
     }
 }
 
 void player_erase()
 {
-    Rect dst = { x, y + MAP_OFFS_Y, 16, 16 };
-    blit(bg, &dst);
+    if (!erase)
+        return;
+
+    Rect dst = { ox, oy + MAP_OFFS_Y, 16, 16 };
+    blit_copy(&dst);
+
+    erase = 0;
 }
 
 void player_draw()
 {
-    Rect dst = { x, y + MAP_OFFS_Y, 16, 16 };
-
-    read_buffer(bg, &dst);
-
-    if (invuln && (invuln & 4))
+    if (dead || (invuln && (invuln & 4)))
         return;
 
+    Rect dst = { x, y + MAP_OFFS_Y, 16, 16 };
     blitrc(binary_sprites_start, &frames[dir][frame], &dst);
+
+    erase = 1;
 }
 
 uint8_t player_collision(Entity *e)
@@ -320,14 +330,14 @@ void player_hit()
     if (use_pickaxe())
     {
         invuln = INVULN_TIME;
-        sound_queue_efx(EFX_HIT);
+        sound_play_efx(EFX_HIT);
     }
     else
     {
         dying = 1;
         frame = FRAME_DYING;
         gravity = GRAVITY_UP;
-        sound_queue_efx(EFX_DEATH);
+        sound_play_efx(EFX_DEATH);
     }
 }
 
diff --git a/src/sound.c b/src/sound.c
index 871fcaa..c9e3b1c 100644
--- a/src/sound.c
+++ b/src/sound.c
@@ -30,11 +30,6 @@ static uint32_t voice = 0;
 
 static MODULE *music = NULL;
 
-#define MAX_QUEUE 4
-
-static uint8_t queue[MAX_QUEUE];
-static uint8_t queue_top;
-
 uint8_t sound_init(uint8_t nosound)
 {
     MikMod_InitThreads();
@@ -71,8 +66,6 @@ uint8_t sound_init(uint8_t nosound)
     Player_Start(music);
     MikMod_EnableOutput();
 
-    queue_top = 0;
-
     return 1;
 }
 
@@ -126,21 +119,3 @@ void sound_play_efx(uint8_t efxno)
     cur = efxno;
     voice = Sample_Play(efx[cur].s, 0, 0);
 }
-
-void sound_queue_efx(uint8_t efxno)
-{
-    if (queue_top >= MAX_QUEUE)
-        return;
-
-    queue[queue_top++] = efxno;
-}
-
-void sound_play_queue()
-{
-    while (queue_top > 0)
-        sound_play_efx(queue[--queue_top]);
-
-    disable();
-    MikMod_Update();
-    enable();
-}
diff --git a/src/sound.h b/src/sound.h
index cd7c20c..d8b14ac 100644
--- a/src/sound.h
+++ b/src/sound.h
@@ -18,9 +18,6 @@ void sound_update();
 void sound_music_pattern(uint16_t pat);
 void sound_play_efx(uint8_t efxno);
 
-void sound_queue_efx(uint8_t efxno);
-void sound_play_queue();
-
 void sound_mute();
 void sound_unmute();
 
diff --git a/src/tmonster.c b/src/tmonster.c
index 30d5714..9f3c618 100644
--- a/src/tmonster.c
+++ b/src/tmonster.c
@@ -34,8 +34,8 @@ static const Rect frames[2 * 4] =
 
 void tmonster_init(Entity *e)
 {
-    e->y = 16;
-    e->x = 32 + (rand() % 256);
+    e->ox = e->y = 16;
+    e->oy = e->x = 32 + (rand() % 256);
     e->dir = e->x > 160 ? DIR_LEFT : DIR_RIGHT;
     e->frames = (const Rect *)frames;
     e->update = tmonster_wait_update;
diff --git a/src/vga.c b/src/vga.c
index ec56b60..13013b2 100644
--- a/src/vga.c
+++ b/src/vga.c
@@ -10,16 +10,22 @@
 
 static uint8_t buffer[320 * 200];
 static uint8_t *screen = NULL;
+static uint8_t *target = NULL;
 
 uint8_t open_framebuffer()
 {
     if (__djgpp_nearptr_enable() == 0)
         return 0;
 
-    screen = (uint8_t *)(0xa0000 + __djgpp_conventional_base);
+    target = screen = (uint8_t *)(0xa0000 + __djgpp_conventional_base);
     return 1;
 }
 
+void blit_target(uint8_t t)
+{
+    target = t ? buffer : screen;
+}
+
 void close_framebuffer()
 {
     __djgpp_nearptr_disable();
@@ -91,94 +97,97 @@ void set_palette(const uint8_t *palette)
 
 void blit(const uint8_t *sprite, const Rect *dst)
 {
-    uint8_t *dbuffer = buffer + dst->x + dst->y * 320;
+    uint8_t b;
+    uint8_t *dtarget = target + dst->x + dst->y * 320;
 
     for (uint16_t j = dst->h; j > 0; j--)
     {
         for (uint16_t i = dst->w; i > 0; i--)
         {
-            uint8_t b = *sprite++;
+            b = *sprite++;
 
             /* transparent */
             if (b == TRANSPARENT)
             {
-                dbuffer++;
+                dtarget++;
                 continue;
             }
 
-            *dbuffer++ = b;
+            *dtarget++ = b;
         }
-        dbuffer += 320 - dst->w;
+        dtarget += 320 - dst->w;
     }
 }
 
 void blit_c(const uint8_t *sprite, const Rect *dst, uint8_t c)
 {
-    uint8_t *dbuffer = buffer + dst->x + dst->y * 320;
+    uint8_t b;
+    uint8_t *dtarget = target + dst->x + dst->y * 320;
 
     for (uint16_t j = dst->h; j > 0; j--)
     {
         for (uint16_t i = dst->w; i > 0; i--)
         {
-            uint8_t b = *sprite++;
+            b = *sprite++;
 
             /* transparent */
             if (b == TRANSPARENT)
             {
-                dbuffer++;
+                dtarget++;
                 continue;
             }
 
-            *dbuffer++ = b ? c : b;
+            *dtarget++ = b ? c : b;
         }
-        dbuffer += 320 - dst->w;
+        dtarget += 320 - dst->w;
     }
 }
 
 void blitrc(const uint8_t *sprite, const Rect *src, const Rect *dst)
 {
-    uint8_t *dbuffer = buffer + dst->x + dst->y * 320;
+    uint8_t b;
+    uint8_t *dtarget = target + dst->x + dst->y * 320;
     sprite += src->x + src->y * src->w;
 
     for (uint16_t j = dst->h; j > 0; j--)
     {
         for (uint16_t i = dst->w; i > 0; i--)
         {
-            uint8_t b = *sprite++;
+            b = *sprite++;
 
             /* transparent */
             if (b == TRANSPARENT)
             {
-                dbuffer++;
+                dtarget++;
                 continue;
             }
 
-            *dbuffer++ = b;
+            *dtarget++ = b;
         }
         sprite += src->w - dst->w;
-        dbuffer += 320 - dst->w;
+        dtarget += 320 - dst->w;
     }
 }
 
 void blit_erase(uint8_t c)
 {
-    memset(buffer, c, 320 * 200);
+    memset(target, c, 320 * 200);
 }
 
-void blit_update()
+void blit_copy_all()
 {
     memcpy(screen, buffer, 320 * 200);
 }
 
-void read_buffer(uint8_t *dst, const Rect *src)
+void blit_copy(const Rect *dst)
 {
-    uint8_t *s = buffer + src->y * 320 + src->x;
+    uint8_t *src = buffer + dst->x + dst->y * 320;
+    uint8_t *dtarget = screen + dst->x + dst->y * 320;
 
-    for (uint16_t j = src->h; j > 0; j--)
+    for (uint16_t j = dst->h; j > 0; j--)
     {
-        for (uint16_t i = src->w; i > 0; i--)
-            *dst++ = *s++;
-
-        s += 320 - src->w;
+        memcpy(dtarget, src, dst->w);
+        src += 320;
+        dtarget += 320;
     }
 }
diff --git a/src/vga.h b/src/vga.h
index 06a69df..2441e24 100644
--- a/src/vga.h
+++ b/src/vga.h
@@ -21,14 +21,20 @@ void wait_frames(uint16_t frames);
 /* the palette is expected to be 8 bit per color, and will be converted to VGA's 6 bit per color */
 void set_palette(const uint8_t *palette);
 
+#define TARGET_SCREEN 0
+#define TARGET_BUFFER 1
+
+void blit_target(uint8_t t);
+
 void blit(const uint8_t *sprite, const Rect *dst);
 /* used for text: skip transparent, ignore 0, replace any other color by c */
 void blit_c(const uint8_t *sprite, const Rect *dst, uint8_t c);
 /* in src w is sprite width, h is sprite height */
 void blitrc(const uint8_t *sprite, const Rect *src, const Rect *dst);
 void blit_erase(uint8_t c);
-void blit_update();
 
-/* read from back buffer into memory */
-void read_buffer(uint8_t *dst, const Rect *src);
+/* copy from back buffer to screen */
+void blit_copy_all();
+void blit_copy(const Rect *dst);
+
 #endif /* _VGA_H */