From cdc8260db19ca06f437115d096bfa1c4e8655fd8 Mon Sep 17 00:00:00 2001
From: Neale Pickett <neale@woozle.org>
Date: Fri, 15 Mar 2013 23:17:38 -0600
Subject: [PATCH] Added NES controller code

---
 main.c | 124 ++++++++++++++++++++++++++++++++++++++++++---------------
 1 file changed, 93 insertions(+), 31 deletions(-)

diff --git a/main.c b/main.c
index 4d3ef45..1973d4c 100644
--- a/main.c
+++ b/main.c
@@ -10,6 +10,8 @@ volatile bool tick = false; // Set high when clock ticks
 uint16_t time = 0; // Tenths of a second elapsed since boot
 
 // Clocks are in deciseconds
+uint16_t score_a = 0;
+uint16_t score_b = 0;
 uint16_t period_clock = 600 * 30;
 uint16_t jam_clock = 600 * 2;
 enum {
@@ -19,22 +21,30 @@ enum {
 	TIMEOUT
 } state = JAM;
 
+uint8_t controller = 0;
+
 
 #define MODE BIT0
 #define SIN BIT1
 #define SCLK BIT2
-#define XLAT BIT4
+#define XLAT BIT3
 // Connect GSCLK to SCLK
 // Connect BLANK to XLAT
 // TRUST ME, THIS TOTALLY WORKS
 
+#define NESCLK BIT4
+#define NESLTCH BIT5
+#define NESSOUT BIT7
+
 #define bit(pin, bit, on) pin = (on ? (pin | bit) : (pin & ~bit))
 
 const uint8_t seven_segment_digits[] = {
-#if 0
+#if defined(WIKIPEDIA)
 	0x3f, 0x06, 0x5b, 0x4f, 0x66, 0x6d, 0x7d, 0x07, 0x7f, 0x6f, 0x77, 0x7c, 0x39, 0x5e, 0x79, 0x71
-#else
+#elseif defined(TOPDOWN)
 	0x7e, 0x48, 0x3d, 0x6d, 0x4b, 0x67, 0x77, 0x4c, 0x7f, 0x6f,
+#else
+	0x7b, 0x09, 0xb3, 0x9b, 0xc9, 0xda, 0xfa, 0x0b, 0xfb, 0xdb
 #endif
 };
 
@@ -76,11 +86,18 @@ write(uint8_t number)
 void
 write_num(uint16_t number, int digits)
 {
+	uint16_t divisor = 1;
 	int i;
 	
+	for (i = 1; i < digits; i += 1) {
+		divisor *= 10;
+	}
+	
 	for (i = 0; i < digits; i += 1) {
-		write(seven_segment_digits[number % 10]);
-		number /= 10;
+		uint16_t n = (number / divisor) % 10;
+		
+		write(seven_segment_digits[n]);
+		divisor /= 10;
 	}
 }
 
@@ -89,8 +106,8 @@ blip()
 {
 	int i;
 	
-	for (i = 0; i < 1000; i += 1) {
-		__delay_cycles(1000);
+	for (i = 0; i < 12; i += 1) {
+		__delay_cycles(1);
 	}
 }
 
@@ -131,21 +148,77 @@ setup_dc()
 void
 draw()
 {
-	write_num(0, 2);  // Score B
+#if 1
+	uint16_t clk;
+
+	write_num(score_a, 3);
 	
-	write_num(jam_clock % 600, 3);
-	write_num(jam_clock / 600, 1);
+	clk = ((period_clock / 10) / 60) * 100;
+	clk = clk + ((period_clock / 10) % 60);
+	write_num(clk, 4);
 	
-	// XXX: Do some kind of animation if period_clock < 200
-	write_num((period_clock / 10) % 60, 2);
-	write_num((period_clock / 10) / 60, 2);
+	clk = ((jam_clock / 600) % 10) * 1000;
+	clk = clk + (jam_clock % 600);
+	write_num(clk, 4);
 	
-	//write_num(0, 2);  // Score A
+	write_num(score_b, 2);
+#else
+	int i;
+	
+	for (i = 0; i < 12; i += 1) {
+		write_num(sizeof(seven_segment_digits) - 1, 1);
+	}
+#endif
 
 	latch();
 	pulse();
 }
 
+/*
+ * Probe the NES controller
+ */
+uint8_t
+nesprobe()
+{
+	int i;
+	uint8_t state = 0;
+
+	P1OUT |= NESLTCH;
+	P1OUT &= ~NESLTCH;
+	
+	for (i = 0; i < 8; i += 1) {
+		state <<= 1;
+		if (P1IN & NESSOUT) {
+			// Button not pressed
+		} else {
+			state |= 1;
+		}
+		P1OUT |= NESCLK;
+		P1OUT &= ~NESCLK;
+	}
+	
+	return state;
+}
+
+void
+update_controller()
+{
+	uint8_t val = nesprobe();
+
+	if (val & 0x80) {
+		switch (state) {
+		case JAM:
+			jam_clock = 300;
+			state = LINEUP;
+			break;
+		default:
+			jam_clock = 600 * 2;
+			state = JAM;
+			break;
+		}
+	}
+}
+
 /*
  * Run logic for this decisecond
  */
@@ -160,30 +233,17 @@ loop()
 		period_clock -= 1;
 	}
 	
-	if (P1IN & BIT3) {
-		switch (state) {
-		case JAM:
-			jam_clock = 300;
-			state = LINEUP;
-			break;
-		default:
-			jam_clock = 600 * 2;
-			state = JAM;
-			break;
-		}
-	}
-	
 	draw();
 }
 
 int
 main(void)
 {
-	int jiffies = 0;
+	uint16_t jiffies = 0;
 
 	WDTCTL = WDTPW + WDTHOLD;	// Disable Watchdog Timer
-	P1DIR |= MODE + SIN + SCLK + XLAT + BIT6;		// P1 output bits
-	P1DIR &= ~(BIT3);
+	P1DIR |= MODE + SIN + SCLK + XLAT + NESCLK + NESLTCH + BIT6;		// P1 output bits
+	P1DIR &= ~(NESSOUT);
 
 	P1OUT = 0;
 		
@@ -191,7 +251,7 @@ main(void)
 	setup_dc();
 
 	// Enable interrupts
-	CCTL0 |= CCIE;		// Trigger interrup on   A checkpoint
+	CCTL0 |= CCIE;		// Trigger interrupt on   A checkpoint
 	TACTL = TASSEL_2 + MC_1;		// Set timer A to SMCLCK, up mode
 	TACCR0 = 0x4444;	// Interrupt 60 times per second
 	
@@ -199,6 +259,8 @@ main(void)
 
 	// Now actually run
 	for (;;) {
+		update_controller();		
+
 		if (tick) {
 			tick = false;
 			jiffies += 1;