example: in-game credits management

Closes #7

10-credits-management/Makefile

@@ -0,0 +1,64 @@
+# Copyright (c) 2020 Damien Ciabrini
+# This file is part of ngdevkit
+#
+# ngdevkit is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Lesser General Public License as
+# published by the Free Software Foundation, either version 3 of the
+# License, or (at your option) any later version.
+#
+# ngdevkit 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 Lesser General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public License
+# along with ngdevkit.  If not, see <http://www.gnu.org/licenses/>.
+
+all: cart nullbios
+
+include ../Makefile.config
+
+# ROM names and common targets
+include ../Makefile.common
+$(CART): $(PROM) $(CROM1) $(CROM2) $(SROM) $(VROM) $(MROM) | rom
+
+OBJS=main
+ELF=rom.elf
+FIX_ASSETS=$(ASSETS)/rom/s1-shadow.bin
+
+$(ASSETS)/rom/c1.bin $(ASSETS)/rom/s1.bin:
+	$(MAKE) -C $(ASSETS)
+
+$(ELF):	$(OBJS:%=%.o)
+	$(M68KGCC) -o $@ $^ `pkg-config --libs ngdevkit`
+
+%.o: %.c
+	$(M68KGCC) `pkg-config --cflags ngdevkit` -std=c99 -fomit-frame-pointer -g -c $< -o $@
+
+# sound driver ROM: ngdevkit's nullsound
+$(MROM): | rom
+	$(Z80SDOBJCOPY) -I ihex -O binary $(NULLSOUNDDIR)/nullsound.ihx $@ --pad-to 131072
+
+# sample ROM: empty
+$(VROM): | rom
+	dd if=/dev/zero bs=1024 count=512 of=$@
+
+# sprite ROM C1 C2: unused, common assets
+$(CROM1): $(ASSETS)/rom/c1.bin | rom
+	cp $(ASSETS)/rom/c1.bin	$@ && $(TRUNCATE) -s 1048576 $@
+
+$(CROM2): $(ASSETS)/rom/c2.bin | rom
+	cp $(ASSETS)/rom/c2.bin	$@ && $(TRUNCATE) -s 1048576 $@
+
+# fixed tile ROM: fonts from common assets
+$(SROM): $(FIX_ASSETS) | rom
+	cat $(FIX_ASSETS) > $@ && $(TRUNCATE) -s 131072 $@
+
+# program ROM
+$(PROM): $(ELF) | rom
+	$(M68KOBJCOPY) -O binary -S -R .comment $< $@ && dd if=$@ of=$@ conv=notrunc,swab
+
+clean:
+	rm -f *.png *.o *~ $(ELF) tmp.* rom/*.*
+
+.PHONY: clean

10-credits-management/main.c

@@ -0,0 +1,289 @@
+/*
+ * Copyright (c) 2021 Damien Ciabrini
+ * This file is part of ngdevkit
+ *
+ * ngdevkit is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as
+ * published by the Free Software Foundation, either version 3 of the
+ * License, or (at your option) any later version.
+ *
+ * ngdevkit 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 Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with ngdevkit.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <ngdevkit/neogeo.h>
+#include <ngdevkit/bios-ram.h>
+#include <ngdevkit/ng-fix.h>
+#include <ngdevkit/ng-video.h>
+#include <stdio.h>
+
+
+// When a ROM starts, the BIOS typically tells it to
+// run in an attract mode until player inserts coins
+// (MVS) or starts the game (AES).
+#define USER_MODE_BOOT 0x0
+#define USER_MODE_DEMO 0x1
+#define USER_MODE_GAME 0x2
+
+// Hardware type as reported in the BIOS RAM
+#define SYSTEM_AES 0x00
+#define SYSTEM_MVS 0x80
+
+
+// demo's prototypes
+void demo_mode();
+void title_mode();
+void game_mode();
+void game_over_screen();
+
+
+// Temporary display buffer
+char str[20];
+
+
+
+// Display text in attract mode
+void update_start_message() {
+    static const char coin[]  = "INSERT COIN";
+    static const char start[] = "PRESS START";
+    static const char empty[] = "           ";
+    static const char* msg;
+    static u8 wait = 30;
+    if (!--wait) {
+        wait = 30;
+        if (msg != empty) {
+            msg = empty;
+        } else if (bios_mvs_flag != SYSTEM_MVS) {
+            // AES has no credits, just asks to press start
+            msg = start;
+        } else {
+            // MVS asks for coins :P
+            msg = coin;
+        }
+        ng_center_text(22, 0, msg);
+    }
+}
+
+// Init the fix layer
+void init_screen() {
+  ng_cls();
+
+  const u16 palette[]={0x8000, 0x0fff, 0x0555};
+  for (u16 i=0; i<3; i++) {
+    MMAP_PALBANK1[i]=palette[i];
+  }
+  // black backdrop color
+  *((volatile u16*)0x401ffe)=0x0;
+}
+
+
+
+// This function is called by the BIOS when the start button of
+// any player is pressed (AES) and when enough credits are available (MVS)
+void player_start(void) {
+    // Retrieve the player that pushed the start button
+    // as reported by the BIOS in bios_start_flag
+    // Note: if the player that pushed start was already
+    // in-game, clear the bit to avoid consuming a credit
+    if (bios_start_flag & 2) {
+        if (!bios_player_mod2) {
+            bios_player_mod2 = 1;
+        } else {
+            bios_start_flag &= ~2;
+        }
+    }
+    if (bios_start_flag & 1) {
+        if (!bios_player_mod1) {
+            bios_player_mod1 = 1;
+        } else {
+            bios_start_flag &= ~1;
+        }
+    }
+
+    // Tell the BIOS that the game has started
+    bios_user_mode = USER_MODE_GAME;
+
+    // When returning to the BIOS, credits will be consumed for
+    // any bit still enabled in bios_start_flag (MVS)
+}
+
+// This function is called by the BIOS when a coin in inserted.
+// It serves as a hook to play a sound with the sound driver.
+void coin_sound(void) {
+}
+
+
+
+// ngdevkit's main() function
+// --------------------------
+// - A typical demo/attract mode consists in:
+//   . the eye catcher animation (hardware logo)
+//   . a game intro plus an arbitrary long demo
+//   . a high score
+//
+// - Once player starts, the ROM enters a game mode
+//
+// - When the game is over:
+//   . the ROM gives back control to the BIOS
+//   . the BIOS restarts the ROM in attrach mode
+//
+int main(void) {
+    init_screen();
+    demo_mode();
+    // when demo ends, only run game is start was pressed
+    if (bios_user_mode == USER_MODE_GAME) game_mode();
+    // returning to the BIOS to start demo again
+    return 0;
+}
+
+
+// ngdevkit's optional main_mvs_title() function
+// ---------------------------------------------
+// - When a coin is inserted, MVS enters a special title
+//   mode that ends demo and give the user 30 seconds to
+//   start the game with one or two players.
+//
+// - Once the 30 seconds are over, the ROM enters game mode
+//
+// - When the game is over:
+//   . the ROM gives back control to the BIOS
+//   . the BIOS restarts the ROM in attrach mode (main())
+//
+int main_mvs_title(void) {
+    init_screen();
+    title_mode();
+    game_mode();
+    // returning to the BIOS to start demo again
+    return 0;
+}
+
+
+void game_status(void) {
+    ng_text(2,3,0,"[game status]");
+    sprintf(str, "p1mod: %x", bios_player_mod1);
+    ng_text(2,4,0,str);
+    sprintf(str, "p2mod: %x", bios_player_mod2);
+    ng_text(2,5,0,str);
+    sprintf(str, "mode:  %x", bios_user_mode);
+    ng_text(2,6,0,str);
+}
+
+void demo_mode() {
+    ng_center_text_tall(8, 0, "DEMO MODE");
+    sprintf(str, "- %s -", (bios_mvs_flag==SYSTEM_MVS)?"MVS":"AES");
+    ng_center_text(11,0,str);
+
+    ng_center_text(16, 0,
+                   (bios_mvs_flag==SYSTEM_MVS)?
+                   "back to eye catcher":
+                   "restart demo mode");
+    ng_center_text(17, 0, "after 15s");
+
+    u16 demo_end=60*15;
+    while(demo_end-- && (bios_user_mode != USER_MODE_GAME)) {
+        game_status();
+        update_start_message();
+        ng_wait_vblank();
+    }
+}
+
+void title_mode() {
+    ng_center_text_tall(8, 0, "TITLE  MODE");
+    sprintf(str, "- %s -", (bios_mvs_flag==SYSTEM_MVS)?"MVS":"AES");
+    ng_center_text(11,0,str);
+
+    ng_center_text(22,0,"PRESS START");
+
+    while(bios_user_mode != USER_MODE_GAME) {
+        game_status();
+        sprintf(str, "%02x", bios_compulsion_timer);
+        ng_center_text(23,0,str);
+        sprintf(str, "credit: %x ", *(u8*)0xd00034);
+        ng_center_text(28,0,str);
+        ng_wait_vblank();
+    }
+}
+
+const char* get_status_string(u8 player_mod) {
+    static const char coin[]  = "INSERT COIN";
+    static const char start[] = "PRESS START";
+    static const char empty[] = "           ";
+    static u8 counter = 120;
+    const char* msg;
+
+    if (!--counter) {
+        counter = 120;
+    }
+
+    if (player_mod != 0) {
+        // running
+        msg = empty;
+    } else {
+        if (counter < 60) {
+            msg = empty;
+        } else if (bios_mvs_flag != SYSTEM_MVS) {
+            // AES has no credits, just asks to press start
+            msg = start;
+        } else {
+            // credits available?
+            if (*(u8*)0xd00034 > 0) {
+                msg = start;
+            } else {
+                msg = coin;
+            }
+        }
+    }
+    return msg;
+}
+
+void update_players_status() {
+    const char* msg;
+    msg = get_status_string(bios_player_mod1);
+    ng_text(2, 29, 0, msg);
+    msg = get_status_string(bios_player_mod2);
+    ng_text(27, 29, 0, msg);
+}
+
+void game_mode() {
+    ng_cls();
+    // in-game backdrop color
+    *((volatile u16*)0x401ffe)=0x488;
+
+    ng_center_text_tall(14, 0, "GAME RUNNING!");
+    ng_center_text(19, 0, "press A to game over 1UP");
+    ng_center_text(20, 0, "press B to game over 2UP");
+
+    while (bios_player_mod1 || bios_player_mod2) {
+        game_status();
+        if (bios_mvs_flag == SYSTEM_MVS) {
+            sprintf(str, "credit: %x ", *(u8*)0xd00034);
+            ng_center_text(28,0,str);
+        }
+
+        // check input for ending player's game
+        if (bios_p1current & 0x10) bios_player_mod1 = 0;
+        if (bios_p1current & 0x20) bios_player_mod2 = 0;
+
+        update_players_status();
+        ng_wait_vblank();
+    }
+
+    // game over: update player's status and show a game over screen
+    game_over_screen();
+}
+
+
+void game_over_screen() {
+    ng_cls();
+    *((volatile u16*)0x401ffe)=0xa00;
+    ng_center_text_tall(14, 0, "GAME OVER");
+    for(u8 wait=120;wait>0;wait--) {
+        game_status();
+        ng_wait_vblank();
+    }
+}

Makefile

@@ -23,7 +23,8 @@ EXAMPLES = \
 06-sound-adpcma \
 07-attract-and-game \
 08-software-dips \
-09-horizontal-sync
+09-horizontal-sync \
+10-credits-management
 
 include Makefile.config
 
@@ -56,6 +57,7 @@ scale 3
 
 # default key mapping
 p1control A=K97,B=K115,C=K113,D=K119,START=K49,COIN=K51,UP=K82,DOWN=K81,LEFT=K80,RIGHT=K79,A=J0B0,B=J0B1,C=J0B2,D=J0B3,START=J0B9,COIN=J0B8,UP=J0a3,DOWN=J0a3,LEFT=J0A0,RIGHT=J0A0
+p2control A=K103,B=K104,C=K116,D=K117,START=K50,COIN=K52,UP=K105,DOWN=K107,LEFT=K106,RIGHT=K108,A=J1B0,B=J1B1,C=J1B2,D=J1B3,START=J1B9,COIN=J1B8,UP=J1a3,DOWN=J1a3,LEFT=J1A0,RIGHT=J1A0
 endef
 
 ifeq ($(ENABLE_MINGW),yes)