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firmware/applications/awake.c

@@ -0,0 +1,212 @@
+#include <sysinit.h>
+#include <stdint.h>
+#include "basic/basic.h"
+#include "funk/nrf24l01p.h"
+//#include "usetable.h"
+
+
+#define AWAKE_PACKET_RETRIES 20
+#define AWAKE_MIN_WINNERS 3
+#define AWAKE_FONT_HEIGHT 8
+
+
+typedef enum packet_type_e {
+	PCKT_WINNER0,
+	PCKT_WINNER1,
+	PCKT_WINNER2,
+	PCKT_WINNER3,
+	PCKT_WINNER4,
+	PCKT_WINNER5,
+	PCKT_WINNER6,
+	PCKT_WINNER7,
+	PCKT_WAKEUP,
+	PCKT_STANDBY,
+	PCKT_NONE
+} packet_type_t;
+
+
+static char const *const awake_gPackets[] = {
+	"winner0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0",
+	"winner1\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0",
+	"winner2\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0",
+	"winner3\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0",
+	"winner4\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0",
+	"winner5\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0",
+	"winner6\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0",
+	"winner7\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0",
+	"wake up\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0",
+	"standby\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"
+};
+
+
+/**
+ * Initializes wireless stuff.
+ */
+static void awake_initNrf(void) {
+	nrf_init();
+	static struct NRF_CFG config = {
+		.channel = 81,
+		.txmac = "\x1\x2\x3\x2\x1",
+		.nrmacs = 1,
+		.mac0 = "\x1\x2\x3\x2\x1",
+		.maclen = "\x20"
+	};
+ 	nrf_config_set(&config);
+ 	nrf_set_strength(3);
+}
+
+
+/**
+ * Polls for a special packet which indicates the success of a player.
+ */
+static packet_type_t awake_waitForPacket(void) {
+	uint8_t buffer[32];
+	if (nrf_rcv_pkt_time(100, 32, buffer) == 32) {
+		for (packet_type_t p = PCKT_WINNER0; p < PCKT_NONE; ++p) {
+			unsigned int bEqual = 1;
+			for (unsigned int i = 0; i < 8; ++i) {
+				if (buffer[i] != awake_gPackets[p][i]) {
+					bEqual = 0;
+					break;
+				}
+			}
+			if (bEqual) {
+				return p;
+			}
+		}
+	}
+	return PCKT_NONE;
+}
+
+
+/**
+ * Waits for either pushed buttons or a signal on the hacker bus.
+ */
+static void awake_waitForKeyPressOrHackerbus(void) {
+	gpioSetDir(RB_HB0, gpioDirection_Input);
+	// watch out for pushed buttons and/or hacker bus activity
+	while (gpioGetValue(RB_HB0) != 0)
+	{
+		if (getInput() != BTN_NONE)
+		{
+			getInputWaitRelease();
+			break;
+		}
+	}
+	while (gpioGetValue(RB_HB0) == 0);
+}
+
+
+/**
+ * The greeter!
+ */
+static void awake_promptUserBegin(void) {
+	gpioSetDir(RB_HB0, gpioDirection_Input);
+
+	lcdFill(0);
+	DoString(0, 0, "Eine Taste");
+	DoString(0, 8, "druecken um");
+	DoString(0,16, "das Spiel");
+	DoString(0,24, "zu starten!");
+	lcdDisplay();
+
+	awake_waitForKeyPressOrHackerbus();
+
+	lcdFill(0);
+	DoString(0,  0, "Spiel laeuft!");
+	DoString(0, 16, "FEUERTASTE");
+	DoString(0, 24, "fuer Standby");
+	lcdDisplay();
+}
+
+
+/**
+ * Informs about the happy end!
+ */
+static void awake_promptUserEnd(void){
+	lcdFill(0);
+	DoString(0,  0, "Es wurden ge-");
+	DoString(0,  8, "nug Gewinner ");
+	DoString(0, 16, "ermittelt!   ");
+	lcdDisplay();
+
+	// toggle RB_HB1 pin from 0V to 3,3 for 200ms
+	GPIO_GPIO0DATA |= (1u << 10);
+	delayms_queue(200);
+	GPIO_GPIO0DATA &= ~(1u << 10);
+
+	awake_waitForKeyPressOrHackerbus();
+}
+
+
+/**
+ * Explains a brief moment of unresponsiveness.
+ */
+static void awake_promptStandby(void){
+	lcdFill(0);
+	DoString(0,  0, "Bitte warten!");
+	DoString(0,  8, "Sende Standby");
+	DoString(0, 16, "Pakete...    ");
+	lcdDisplay();
+}
+
+
+void awake_initHackerBus() {
+	// set RB_HB1 to GPIO mode (output)
+	#define IOCON_PIO0_10 (*((REG32*) (0x40044068)))
+	IOCON_PIO0_10 &= ~(00000007);
+	IOCON_PIO0_10 |= 0x00000001;
+	GPIO_GPIO0DIR |= (1 << 10);
+	GPIO_GPIO0DATA &= ~(1 << 10);
+}
+
+/**
+ * Main function of the l0dable.
+ */
+void main_awake(void) {
+	awake_initNrf();
+	awake_initHackerBus();
+
+	while (1) {
+		awake_promptUserBegin();
+		uint8_t joyinput = BTN_NONE;
+		unsigned int nWinnerFlags = 0, nWinnerCount = 0;
+		while ((joyinput != BTN_ENTER) && (nWinnerCount < AWAKE_MIN_WINNERS)) {
+			if ((joyinput = getInput()) != BTN_NONE)
+			{
+				getInputWaitRelease();
+			}
+
+			// send a "wake up" packet every loop cycle so that in case a r0ket
+			// is rebooted, the player can continue the game
+			uint8_t packet[32];
+			memcpy(packet, awake_gPackets[PCKT_WAKEUP], 32);
+			delayms(10);
+			nrf_snd_pkt_crc(32, packet);
+
+			// watch out for winners!
+			packet_type_t const ePacket = awake_waitForPacket();
+			unsigned int const nWinnerMask = (1 << ePacket) & 0xFF;
+			if ((ePacket <= PCKT_WINNER7) && !(nWinnerFlags & nWinnerMask)) {
+				nWinnerFlags |= nWinnerMask;
+				++nWinnerCount;
+				DoIntX(0, 32, nWinnerMask);
+				lcdDisplay();
+			}
+		}
+
+		if (nWinnerCount >= AWAKE_MIN_WINNERS) {
+			awake_promptUserEnd();
+		}
+
+		awake_promptStandby();
+		uint8_t packet[32];
+		for (int i = 0; i < AWAKE_PACKET_RETRIES; ++i) {
+			delayms_queue(50);
+			memcpy(packet, awake_gPackets[PCKT_STANDBY], 32);
+			nrf_snd_pkt_crc(32, packet);
+		}
+	}
+
+	return;
+}

firmware/applications/poem.c

@@ -0,0 +1,649 @@
+#include <sysinit.h>
+#include <string.h>
+
+#include "basic/basic.h"
+#include "basic/random.h"
+#include "basic/config.h"
+#include "lcd/render.h"
+#include "lcd/backlight.h"
+#include "lcd/allfonts.h"
+#include "funk/nrf24l01p.h"
+
+
+#define POEM_ID 4
+
+#define BTN_WAKEUP (1 << 5)
+#define BTN_STANDBY (1 << 6)
+
+#define POEM_FONT_WIDTH     5
+#define POEM_FONT_HEIGHT    8
+#define POEM_FONT           Font_5x8
+
+#define POEM_COUNT          5u
+#define POEM_VERSE_COUNT    4u
+#define POEM_MAX_LINE_COUNT (RESY / POEM_FONT_HEIGHT)
+#define POEM_LINE_LIMIT     ((RESX - 4) / POEM_FONT_WIDTH)
+
+
+#define POEM_PACKET_RETRIES 10
+
+typedef enum packet_type_e {
+	PCKT_WINNER0,
+	PCKT_WINNER1,
+	PCKT_WINNER2,
+	PCKT_WINNER3,
+	PCKT_WINNER4,
+	PCKT_WINNER5,
+	PCKT_WINNER6,
+	PCKT_WINNER7,
+	PCKT_WAKEUP,
+	PCKT_STANDBY,
+	PCKT_NONE
+} packet_type_t;
+
+
+static char const *const poem_gPackets[10] = {
+	"winner0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0",
+	"winner1\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0",
+	"winner2\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0",
+	"winner3\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0",
+	"winner4\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0",
+	"winner5\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0",
+	"winner6\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0",
+	"winner7\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0",
+	"wake up\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0",
+	"standby\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"
+};
+
+
+typedef enum poem_state_e {
+	POEM_STATE_STANDBY,
+	POEM_STATE_USAGE,
+	POEM_STATE_PLAYING,
+	POEM_STATE_WON
+} poem_state_t;
+
+
+typedef struct poem_break_marker_s {
+	unsigned int nStart;
+	unsigned int nStop;
+} poem_break_marker_t;
+
+
+typedef struct poem_s {
+	char const * const pszVerses[POEM_VERSE_COUNT];
+	unsigned int nLineCounts[POEM_VERSE_COUNT];
+	unsigned int nPermut[POEM_VERSE_COUNT];
+	poem_break_marker_t pszMarkers[POEM_VERSE_COUNT][POEM_MAX_LINE_COUNT];
+} poem_t;
+
+
+static poem_t g_poem_aPoems[POEM_COUNT]=
+		{
+#if POEM_ID == 0
+		 // Goethe - An den Mond, 3. Vers
+		 {{"Jeden Nachklang fuehlt mein Herz",
+		   "Froh und trueber Zeit,",
+		   "Wandle zwischen Freud' und Schmerz",
+		   "In der Einsamkeit."}},
+
+		 // Goethe - Gefunden, 3. Vers
+		 {{"Ich wollt es brechen,",
+		   "Da sagt es fein:",
+		   "Soll ich zum Welken",
+		   "Gebrochen sein?"}},
+
+		 // Grillparzer - In der Fremde, 2. Vers
+		 {{"So willst Du denn nach Hause?",
+		   "O nein! Nur nicht nach Haus!",
+		   "Dort stirbt des Lebens Leben",
+		   "Im Einerlei mir aus."}},
+
+		 // Friedrich Schiller - Pilgrim, 1. Vers
+		 {{"Noch in meines Lebens Lenze",
+		   "War ich, und ich wandert' aus,",
+		   "Und der Jugend frohe Taenze",
+		   "Liess ich in des Vaters Haus."}},
+
+		 // Frank Wedekind - Erdgeist, 2. Vers
+		 {{"Meide nicht die ird'schen Schaetze:",
+		   "Wo sie liegen, nimm sie mit.",
+		   "Hat die Welt doch nur Gesetze,",
+		   "Dass man sie mit Fuessen tritt."}},
+#elif POEM_ID == 1
+		 // Clemens Brentano - Loreley
+		 {{"Zu Bacharach am Rheine",
+		   "Wohnt eine Zauberin,",
+		   "Die war so schoen und feine",
+		   "Und riss viel Herzen hin."}},
+
+		 // Wilhelm Busch - Frueher, da ich unerfahren
+		 {{"Frueher, da ich unerfahren",
+		   "Und bescheidner war als heute,",
+		   "Hatten meine hoechste Achtung",
+		   "Andre Leute."}},
+
+		 // Heinz Erhardt - Warum die Zitronen sauer wurden
+		 {{"Bis sie einst sprachen: 'Wir Zitronen,",
+		   "wir wollen gross sein wie Melonen!",
+		   "Auch finden wir das Gelb abscheulich,",
+		   "wir wollen rot sein oder blaeulich!'"}},
+
+		 // Joseph von Eichendorff - Mondnacht
+		 {{"Die Luft ging durch die Felder,",
+		   "Die Aehren wogten sacht,",
+		   "Es rauschten leis' die Waelder,",
+		   "So sternklar war die Nacht."}},
+
+		 // Theodor Fontane - Trost
+		 {{"Harre, hoffe. Nicht vergebens",
+		   "zaehlest du der Stunden Schlag:",
+		   "Wechsel ist das Los des Lebens,",
+		   "Und - es kommt ein andrer Tag."}},
+#elif POEM_ID == 2
+		 // Goethe - Der Zauberlehrling
+		 {{"Ach, da kommt der Meister!",
+		   "Herr, die Not ist gross!",
+		   "Die ich rief, die Geister,",
+		   "Werd ich nun nicht los."}},
+
+		 // Schiller - Das Lied von der Glocke
+		 {{"Fest gemauert in der Erden",
+		   "Steht die Form, aus Lehm gebrannt.",
+		   "Heute muss die Glocke werden!",
+		   "Frisch, Gesellen, seid zur Hand!"}},
+
+		 // Hermann Hesse - Im Nebel
+		 {{"Voll von Freunden war mir die Welt",
+		   "Als noch mein Leben licht war;",
+		   "Nun, da der Nebel faellt,",
+		   "Ist keiner mehr sichtbar."}},
+
+		 // irgend ein Kinderlied
+		 {{"Schoen ist der Zylinderhut",
+		   "Wenn man ihn besitzen tut",
+		   "Doch von ganz besondrer Guete",
+		   "Sind stets zwei Zylinderhuete"}},
+
+		 // Conrad Ferdinand Meyer - Alles war ein Spiel
+		 {{"In diesen Liedern suche du",
+		   "Nach keinem ernsten Ziel!",
+		   "Ein wenig Schmerz, ein wenig Lust,",
+		   "Und alles war ein Spiel."}},
+#elif POEM_ID == 3
+		 // Friedrich Nietzsche - Vereinsamt
+		 {{"Die Kraehen schrein",
+		   "Und ziehen schwirren Flugs zur Stadt:",
+		   "Bald wird es schnein, -",
+		   "Wohl dem, der jetzt noch - Heimat hat!"}},
+
+		 // Christian Morgenstern - Der Werwolf
+		 {{"Dem Werwolf schmeichelten die Faelle,",
+		   "er rollte seine Augenbaelle.",
+		   "Indessen, bat er, fuege doch",
+		   "zur Einzahl auch die Mehrzahl noch!"}},
+
+		 // Wilhelm Busch - Dummheit, die man bei den anderen sieht
+		 {{"Wenn andere klueger sind als wir,",
+           "Das macht uns selten nur Plaesier,",
+           "Doch die Gewissheit, dass sie duemmer,",
+           "Erfreut fast immer."}},
+
+         // August von Kotzebue - Gesellschaftslied, 2. Vers
+		 {{"Wir sitzen so froehlich beisammen",
+		   "Wir haben uns alle so lieb,",
+		   "Wir heitern einander das Leben,",
+		   "Ach wenn es doch immer so blieb'!"}},
+
+		 // Gotthold Ephraim Lessing - Antwort eines trunknen Dichters, 1. Vers
+		 {{"Ein trunkner Dichter leerte",
+		   "Sein Glas auf jeden Zug;",
+		   "Ihn warnte sein Gefaehrte:",
+		   "Hoer' auf! du hast genug."}},
+#elif POEM_ID == 4
+		 // Hermann von Lingg - Das Krokodil, 1. Vers
+		 {{"Im heil'gen Teich zu Singapur,",
+		   "Da liegt ein altes Krokodil",
+		   "Von aeusserst graemlicher Natur",
+		   "Und kaut an einem Lotosstiel."}},
+
+		 // Hermann Loens - Wegewarte, 2. Vers
+		 {{"Ich stand an dem Wege,",
+		   "Hielt auf meine Hand,",
+		   "Du hast Deine Augen",
+		   "Von mir abgewandt."}},
+
+		 // Christian Morgenstern - An meine Taschenuhr, 1. und einziger Vers
+		 {{"Du schlimme Uhr, du gehst mir viel zu schnell;",
+		   "und doch - dich schauend, sah ich selber hell.",
+		   "Unschuldig Raederwerk, was schalt ich dich?",
+		   "Ich geh zu langsam, ach zu langsam - ich."}},
+
+		 // Eduard Moerike - Jaegerlied, 2.Vers
+		 {{"In die Luefte hoch der Reiher steigt,",
+		   "dahin weder Pfeil noch Kugel fleugt:",
+		   "Tausendmal so hoch und so geschwind",
+		   "die Gedanken treuer Liebe sind."}},
+
+		 // Erich Muehsam - Liebesweh, 3. Vers
+		 {{"Ach, es ist der Traum der Liebe,",
+		   "den ich durch die Seele siebe.",
+		   "Ach, es ist der Liebe Weh,",
+		   "das mich zwickt vom Kopf zur Zeh."}},
+#elif POEM_ID == 5
+		 // Wilhelm Mueller - Der Glockenguss zu Breslau, 6. Vers
+		 {{"Wie hat der gute Meister",
+		   "So treu das Werk bedacht!",
+		   "Wie hat er seine Haende",
+		   "Geruehrt bei Tag und Nacht!"}},
+
+		 // Ludwig Pfau - Der Geiger von Oppenau, 2. Vers
+		 {{"Wo seine Fiedel geklungen,",
+		   "Da konnte kein Fuss mehr stehn,",
+		   "Da sprangen die Alten und Jungen,",
+		   "Die Stube fing an zu drehn."}},
+
+		 // Robert Reinick - Der Faule, 2. Vers
+		 {{"Doch die Zeit wird lang mir werden,",
+		   "Und wie bring' ich sie herum?",
+		   "Spitz! komm her! dich will ich lehren",
+		   "Hund, du bist mir viel zu dumm!"}},
+
+		 // Rainer Maria Rilke - Herbsttag, 2. Vers
+		 {{"Befiehl den letzten Fruechten voll zu sein;",
+		   "gib ihnen noch zwei suedlichere Tage,",
+		   "draenge sie zur Vollendung hin und jage",
+		   "die letzte Suesse in den schweren Wein."}},
+
+		 // Joachim Ringelnatz - Ehrgeiz
+		 {{"Ich habe meinen Soldaten aus Blei",
+		   "Als Kind Verdienstkreuzchen eingeritzt.",
+		   "Mir selber ging alle Ehre vorbei,",
+		   "Bis auf zwei Orden, die jeder besitzt."}}
+#endif
+		};
+
+
+/**
+ * Prepares markers for line wrapping and determines the number of lines
+ * required to display a verse.
+ */
+static void poem_prepareLineWrappingMarkers(void) {
+	for (unsigned int iPoem = 0; iPoem < POEM_COUNT; ++iPoem) {
+		for (unsigned int iVerse = 0; iVerse < POEM_VERSE_COUNT; ++iVerse) {
+			char const * const psz = g_poem_aPoems[iPoem].pszVerses[iVerse];
+			size_t const nLen = strlen(psz);
+			unsigned int nPos = 0, nCharCnt = 0, nLineCount = 0;
+			int nLastSpc = -1;
+
+			poem_break_marker_t *pMarker =
+					&g_poem_aPoems[iPoem].pszMarkers[iVerse][nLineCount];
+			while ((nPos < nLen) && (nLineCount < POEM_MAX_LINE_COUNT)) {
+				if (nCharCnt < POEM_LINE_LIMIT && (nPos != (nLen - 1))) {
+					if (psz[nPos] == ' ') {
+						nLastSpc = nPos;
+					}
+					++nCharCnt;
+				} else {
+					pMarker->nStart = nPos - nCharCnt;
+					if (nPos == (nLen - 1)) {
+						pMarker->nStop = nPos;
+					} else if (nLastSpc < (nPos - nCharCnt)) {
+						pMarker->nStop = nPos - 1;
+					} else {
+						pMarker->nStop = nLastSpc;
+						nPos = nLastSpc;
+					}
+					pMarker = &g_poem_aPoems[iPoem].pszMarkers[iVerse][++nLineCount];
+					nCharCnt = 0;
+				}
+				++nPos;
+			}
+			g_poem_aPoems[iPoem].nLineCounts[iVerse] = nLineCount;
+		}
+	}
+}
+
+
+/**
+ * Prints a physical line (that is one row of displayed characters) from a given
+ * poem and verse.
+ * @param pPoem The poem where to look for that line.
+ * @param nVerse The verse where the to be printed line resides.
+ * @param nLine The position (counting from 0) of that line within that verse.
+ * @param y The vertical offset where text should be rendered.
+ */
+static void poem_printLine(poem_t const *const pPoem, unsigned int nVerse,
+		unsigned int nLine, int y) {
+	char pszLine[POEM_LINE_LIMIT + 1] = { 0 };
+	poem_break_marker_t const * const pMarker =
+			&pPoem->pszMarkers[nVerse][nLine];
+	for (unsigned int k = pMarker->nStart; k <= pMarker->nStop; ++k) {
+		pszLine[k - pMarker->nStart] = pPoem->pszVerses[nVerse][k];
+	}
+	DoString(2, y, pszLine);
+}
+
+
+/**
+ * Shuffles the verses of a given poem.
+ * @param pPoem The poem whose verses need to be shuffled.
+ */
+static void poem_initPermutation(poem_t *const pPoem) {
+	for (unsigned int i = POEM_VERSE_COUNT; i--;) {
+		pPoem->nPermut[i] = i;
+	}
+	while ((pPoem->nPermut[0] < pPoem->nPermut[1])
+			&& (pPoem->nPermut[1] < pPoem->nPermut[2])
+			&& (pPoem->nPermut[2] < pPoem->nPermut[3])) {
+		for (unsigned int i = 4; i--;) {
+			unsigned int const nIndexA = getRandom() % POEM_VERSE_COUNT;
+			unsigned int const nIndexB = getRandom() % POEM_VERSE_COUNT;
+
+			unsigned int nSwap = pPoem->nPermut[nIndexA];
+			pPoem->nPermut[nIndexA] = pPoem->nPermut[nIndexB];
+			pPoem->nPermut[nIndexB] = nSwap;
+		}
+	}
+}
+
+uint8_t poem_identifyPacket(uint8_t *packet){
+	uint8_t input = BTN_NONE;
+	if (strncmp((char *)packet, poem_gPackets[PCKT_STANDBY], 8) == 0) {
+		input = BTN_STANDBY;
+	} else if (strncmp((char *)packet, poem_gPackets[PCKT_WAKEUP], 8) == 0) {
+		input = BTN_WAKEUP;
+	}
+	return input;
+}
+
+
+/**
+ * Watches for both joystick movements and standby NRF packets. It's blocks the
+ * control flow as long as there are neither appropriate joystick activities nor
+ * standby/wake up packets received.
+ * @param filter A mask of events to which this function should react.
+ * @return One of BTN_(UP|DOWN|LEFT|RIGHT|ENTER|STANDBY|WAKEUP).
+ */
+uint8_t poem_getInputBlocking(uint8_t filter) {
+	uint8_t pkt[32];
+	uint8_t input = BTN_NONE;
+	nrf_rcv_pkt_start();
+	do {
+		if ((nrf_rcv_pkt_poll(sizeof(pkt), pkt) != 32) ||
+				!((input = poem_identifyPacket(pkt)) & filter)) {
+			input = getInput();
+		}
+	} while (!(filter & input));
+	nrf_rcv_pkt_end();
+	return input;
+}
+
+
+/**
+ * Watches for both joystick movements and standby NRF packets. It returns
+ * BTN_NONE if there's neither a NRF packet nor joystick input.
+ * @return One of BTN_(NONE|UP|DOWN|LEFT|RIGHT|ENTER|STANDBY|WAKEUP).
+ */
+uint8_t poem_getInputNonBlocking(void) {
+	uint8_t pkt[32];
+	uint8_t input;
+	if (nrf_rcv_pkt_poll(sizeof(pkt), pkt) == 32) {
+		input = poem_identifyPacket(pkt);
+		if (input == BTN_NONE)
+			input == getInput();
+	}
+	else {
+		input = getInput();
+	}
+	return input;
+}
+
+
+/**
+ * Displays a small description of the game.
+ */
+static void poem_printUsage(void) {
+	// show usage
+	int dy = 0;
+	lcdFill(0);
+	DoString(0, dy, "Sortiere die Verse ");	dy += POEM_FONT_HEIGHT;
+	DoString(0, dy, "in die richtige    ");	dy += POEM_FONT_HEIGHT;
+	DoString(0, dy, "Reihenfolge! Der   ");	dy += POEM_FONT_HEIGHT;
+	DoString(0, dy, "Knopf ist ein Joy- ");	dy += POEM_FONT_HEIGHT;
+	DoString(0, dy, "stick. Waehle einen");	dy += POEM_FONT_HEIGHT;
+	DoString(0, dy, "Vers mit OBEN oder ");	dy += POEM_FONT_HEIGHT;
+	DoString(0, dy, "UNTEN. Verschiebe  ");	dy += POEM_FONT_HEIGHT;
+	DoString(0, dy, "ihn per FEUERTASTE.");	dy += POEM_FONT_HEIGHT;
+	lcdDisplay();
+}
+
+
+/**
+ * Initializes the wireless stuff.
+ */
+static void poem_initRadio(void) {
+	nrf_init();
+ 	static struct NRF_CFG config = {
+		.channel = 81,
+		.txmac = "\x1\x2\x3\x2\x1",
+		.nrmacs = 1,
+		.mac0 = "\x1\x2\x3\x2\x1",
+		.maclen = "\x20",
+	};
+	nrf_config_set(&config);
+	delayms(50);
+}
+
+
+/**
+ * Turns on the backlight and switches to dark text on a light background.
+ */
+static void poem_turnOnBacklight(void) {
+	GLOBAL(daytrig) = 255;
+	GLOBAL(daytrighyst) = 50;
+	GLOBAL(dayinvert) = 0;
+	GLOBAL(lcdinvert) = 1;
+	backlightSetBrightness(100);
+	lcdSetInvert(1);
+	lcdFill(0);
+	lcdDisplay();
+}
+
+
+/**
+ * Turns off the backlight and switches to light text on a dark background.
+ */
+static void poem_turnOffBacklight(void) {
+	GLOBAL(daytrig) = 0;
+	GLOBAL(daytrighyst) = 50;
+	GLOBAL(dayinvert) = 0;
+	GLOBAL(lcdinvert) = 0;
+	backlightSetBrightness(0);
+	lcdSetInvert(0);
+	lcdFill(0);
+	lcdDisplay();
+}
+
+
+/**
+ * Highlights the specified item by drawing a bounding box around it (to
+ * indicate a selection) or by inverting its representation (dragging).
+ * @param bIsDragging Whether the item is just selected or about to be dragged.
+ * @param nStartY The (absolute) start offset (in pixels) of the item.
+ * @param nStopY The (absolute) stop offset (in pixels) of the item.
+ * @param nScroll The vertical scrolling offset.
+ */
+static void poem_hightlightSelectedItem(unsigned int const bIsDragging,
+		int nStartY, int const nStopY, int const nScroll) {
+	// invert or draw a bounding box around the selected verse
+	if (bIsDragging) {
+		// dragging mode: invert the to be dragged item
+		for (int y = nStartY; y < nStopY; ++y) {
+			for (int x = 0; x < RESX; ++x) {
+				lcdSetPixel(x, y - nScroll, !lcdGetPixel(x, y - nScroll));
+			}
+		}
+	} else {
+		// selection mode: draw a border around the selected item
+		for (int x = 0; x < RESX; ++x) {
+			lcdSetPixel(x, nStartY - nScroll, 1);
+			lcdSetPixel(x, nStopY - nScroll, 1);
+		}
+		for (int y = nStartY; y < nStopY; ++y) {
+			lcdSetPixel(0, y - nScroll, 1);
+			lcdSetPixel(RESX - 1, y - nScroll, 1);
+		}
+	}
+}
+
+
+/**
+ * Informs the master device that the player has accomplished the task and
+ * blocks as long as there are no "standby" or "wakeup" packets.
+ */
+static void poem_sendSuccessMessage(packet_type_t pktWinner) {
+	// send our winner information packet
+	static uint8_t pkt[32];
+
+	nrf_rcv_pkt_start();
+	while (1) {
+		memcpy(pkt, poem_gPackets[pktWinner], sizeof(pkt));
+		nrf_snd_pkt_crc(sizeof(pkt), pkt);
+		delayms_queue(80 + (getRandom() % 50));
+		uint8_t input = poem_getInputNonBlocking();
+		if (input == BTN_STANDBY) {
+			break;
+		}
+	}
+	nrf_rcv_pkt_end();
+}
+
+
+/**
+ * Starts a game where the user has to sort verses of a poem into the right
+ * order.
+ */
+void main_poem(void) {
+	packet_type_t pktWinner = POEM_ID;
+
+	// display initialization
+	font = &POEM_FONT;
+
+	// init wireless stuff
+	poem_initRadio();
+	poem_prepareLineWrappingMarkers();
+
+	poem_state_t state = POEM_STATE_STANDBY;
+
+	while (1) {
+		switch (state) {
+		case POEM_STATE_STANDBY:
+			poem_turnOffBacklight();
+			lcdFill(0);
+			DoInt(0, 0, pktWinner);
+			lcdDisplay();
+			poem_getInputBlocking(BTN_WAKEUP);
+			state = POEM_STATE_USAGE;
+			break;
+
+		case POEM_STATE_USAGE:
+			poem_turnOnBacklight();
+			poem_printUsage();
+			{
+				uint8_t input = poem_getInputBlocking(BTN_UP | BTN_DOWN |
+						BTN_LEFT | BTN_RIGHT | BTN_ENTER | BTN_STANDBY);
+				if (input == BTN_STANDBY) {
+					state = POEM_STATE_STANDBY;
+				}
+				else if (input != BTN_WAKEUP) {
+					state = POEM_STATE_PLAYING;
+				}
+			}
+			DoString(20,0, "bla");
+			lcdDisplay();
+			break;
+
+		case POEM_STATE_PLAYING:
+			{
+				// print the verses
+				poem_t *const pPoem = &g_poem_aPoems[getRandom() % POEM_COUNT];
+				poem_initPermutation(pPoem);
+				unsigned int nSelectedVerse = 0, nNextSelected = 0;
+				unsigned int bIsDragging = 0;
+				while (state == POEM_STATE_PLAYING) {
+					// Calculate position and size of the bounding box of the selected
+					// verse. Also, calculate a vertical scrolling offset to ensure
+					// that the selected verse is visible.
+					int nStartY = 0;
+					for (unsigned int i = 0; i < nSelectedVerse; ++i) {
+						unsigned int index = pPoem->nPermut[i];
+						nStartY += POEM_FONT_HEIGHT * pPoem->nLineCounts[index] + 3;
+					}
+					const int nStopY = 2 + nStartY	+ (POEM_FONT_HEIGHT
+								* pPoem->nLineCounts[pPoem->nPermut[nSelectedVerse]]);
+					int nScroll = nStopY >= RESY ? nStopY - RESY + 1 : 0;
+					// display verses
+					lcdFill(0);
+					int dy = 2;
+					for (unsigned int i = 0; i < POEM_VERSE_COUNT; ++i) {
+						unsigned int const index = pPoem->nPermut[i];
+						for (unsigned int j = 0; j < pPoem->nLineCounts[index]; ++j) {
+							poem_printLine(pPoem, index, j, dy - nScroll);
+							dy += POEM_FONT_HEIGHT;
+						}
+						dy += 3;
+					}
+					// draw a bounding box around the selected verse (or invert it)
+					poem_hightlightSelectedItem(bIsDragging, nStartY, nStopY, nScroll);
+					// flush display buffer
+					lcdDisplay();
+
+					// both query joystick and listen for "standby" packets;
+					switch (poem_getInputBlocking(BTN_UP | BTN_DOWN |
+							BTN_ENTER | BTN_STANDBY)) {
+					case BTN_ENTER:
+						bIsDragging = !bIsDragging;
+						if (!bIsDragging && pPoem->nPermut[0] < pPoem->nPermut[1]
+								&& pPoem->nPermut[1] < pPoem->nPermut[2]
+								&& pPoem->nPermut[2] < pPoem->nPermut[3]) {
+							state = POEM_STATE_WON;
+						}
+						break;
+
+					case BTN_UP:
+						nNextSelected = nSelectedVerse > 0 ?
+								nSelectedVerse - 1 : nSelectedVerse;
+						break;
+
+					case BTN_DOWN:
+						nNextSelected = nSelectedVerse < (POEM_VERSE_COUNT - 1) ?
+								nSelectedVerse + 1 : nSelectedVerse;
+						break;
+
+					case BTN_STANDBY:
+						state = POEM_STATE_STANDBY;
+						break;
+					}
+
+
+					if (nSelectedVerse != nNextSelected && bIsDragging) {
+						unsigned int temp = pPoem->nPermut[nSelectedVerse];
+						pPoem->nPermut[nSelectedVerse] = pPoem->nPermut[nNextSelected];
+						pPoem->nPermut[nNextSelected] = temp;
+					}
+					nSelectedVerse = nNextSelected;
+				}
+			}
+			break;
+
+		case POEM_STATE_WON:
+			lcdFill(0);
+			DoString(22, 30, "Geschafft!");
+			lcdDisplay();
+			poem_sendSuccessMessage(pktWinner);
+			state = POEM_STATE_STANDBY;
+			break;
+		}
+	}
+}