From 49d931ef91c8c54a92610087e6701c039151afca Mon Sep 17 00:00:00 2001
From: Drew Fisher <drew.m.fisher@gmail.com>
Date: Sun, 20 Jun 2010 17:49:36 -0700
Subject: [PATCH] Functional code for SNES port 2.

The assembly routine doesn't work.  No idea why; I'll rework it later.
In the meantime, it's a bad idea to poll the SNES in an interrupt
routine, so the interrupt now sets readyToPollSnes every 1/60th of a
second instead, and the actual polling code has been placed in
getButtons().

This will likely all need a rework when I move to support polling two
controllers simultaneously.
---
 main.c | 58 ++++++++++++++++++++++++++++++++++++++++++++--------------
 1 file changed, 44 insertions(+), 14 deletions(-)

diff --git a/main.c b/main.c
index b08d094..44b3cd3 100644
--- a/main.c
+++ b/main.c
@@ -41,7 +41,7 @@ typedef struct {
 	//uchar id;
 	char x;
 	char y;
-	uchar buttons;
+	uchar buttons; // Note: bitstream goes [8...1]
 } report_t;
 
 static report_t buttonState;
@@ -49,6 +49,7 @@ static report_t reportBuffer;
 static uint8_t pollInProgress = 0;
 static unsigned char idleRate;
 static uint8_t interrupt_count = 0;
+static uint8_t readyToPollSnes = 0;
 
 usbMsgLen_t usbFunctionSetup(uchar data[8]) {
 
@@ -69,7 +70,7 @@ usbMsgLen_t usbFunctionSetup(uchar data[8]) {
 		} else if (rq->bRequest == USBRQ_HID_SET_IDLE){
 			idleRate = rq->wValue.bytes[1];
 		}
-	}else{
+	} else {
 		/* no vendor specific requests implemented */
 	}
 	return 0;   /* default for not implemented requests: return no data back to host */
@@ -77,18 +78,42 @@ usbMsgLen_t usbFunctionSetup(uchar data[8]) {
 
 
 ISR(TIMER1_COMPA_vect) {
-/*
-	if(pollInProgress) // Mutex, to prevent infinite recursion if terribly many USB interrupts (shouldn't happen, but safety net)
-		return; // We've already started polling the SNES controller, return up the stack so that the original ISR can finish
-	pollInProgress = 1; // Acquire lock
-	sei(); // Allow for nested interrupts - namely, USB interrupts.
-	buttonState.buttons = pollSnes();
-	pollInProgress = 0; // Release lock
-*/
-	if (interrupt_count++ == 60) {
-		reportBuffer.buttons++;
-		interrupt_count = 0;
+	readyToPollSnes = 1; // Set flag for mainloop to poll SNES (better not to do this in an ISR)
+}
+
+static void getButtons() { // Poll the SNES for the button states, arrange bytes appropriately for the descriptor
+	uint16_t temp= 0x0000;
+	uint8_t counter = 16;
+
+	PORTC |= _BV(PINC1);
+	_delay_us(12);
+
+	PORTC &= ~_BV(PINC1);
+
+	for(counter = 0; counter != 16; counter++) {
+		_delay_us(6);
+		temp = temp << 1 ;
+		temp |= (PINC & _BV(PINC2)) ? 0 : 1;
+		PORTC &= ~_BV(PINC0);
+		_delay_us(6);
+		PORTC |= _BV(PINC0);
 	}
+
+	if (temp & 0x0800)
+		buttonState.y = -127;
+		//buttonState.x = 127;
+	else if (temp & 0x0400)
+		buttonState.y = 127;
+		//buttonState.x = -127;
+	else buttonState.y = 0;
+
+	if (temp & 0x0200)
+		buttonState.x = -127;
+	else if (temp & 0x0100)
+		buttonState.x = 127;
+	else buttonState.x = 0;
+	buttonState.buttons = ((temp & 0xf000) >> 8) | ((temp & 0x00f0) >> 4) ;
+	readyToPollSnes = 0;
 }
 
 static void initPins() {
@@ -174,10 +199,15 @@ int main(void)
 		//DBG1(0x02, 0, 0);   /* debug output: main loop iterates */
 		wdt_reset();
 		usbPoll();
+		if(readyToPollSnes) {
+			getButtons();
+		}
 		if(usbInterruptIsReady()){
 			/* called after every poll of the interrupt endpoint */
 			// Actual code to be executed - updates the HID report with the status of the SNES controller
-			//reportBuffer.buttons = buttonState.buttons;
+			reportBuffer.x = buttonState.x;
+			reportBuffer.y = buttonState.y;
+			reportBuffer.buttons = buttonState.buttons;
 
 			// Testing USB reports - change button state every second, incrementing the report buffer by 1.
 			//if(counter++ == 10) {
-- 
2.39.5