Update to v086r05 release.

byuu says:

USART implements reading and writing, but I don't yet have code to test
SNES reading yet.
So ... obviously I need to do that next.

Went ahead and required nall::function, so the modules will have to be
C++11. I don't see anyone else making these, and it avoids the annoyance
of deducing the correct controller port based on dynamic casting the
active thread.
Apparently a library can have a main() function to no ill effect, so
there's no need for USART_HARDWARE. Same exact code with different flags
will make the binary and the library.

bsnes/base/base.hpp

@@ -1,7 +1,7 @@
 #ifndef BASE_HPP
 #define BASE_HPP
 
-const char Version[] = "086.04";
+const char Version[] = "086.05";
 
 #include <nall/platform.hpp>
 #include <nall/algorithm.hpp>

bsnes/snes/controller/usart/usart.cpp

@@ -16,14 +16,35 @@
 // IOBit   ---
 // GND     GND
 
-static uint8 usart_read();
-static void usart_write(uint8 data);
+void USART::enter() {
+  main({ &USART::usleep, this }, { &USART::read, this }, { &USART::write, this });
+  while(true) step(1000000);  //fallback; main should never return
+}
+
+void USART::usleep(unsigned milliseconds) {
+  step(milliseconds);
+}
+
+//SNES -> USART
+uint8 USART::read() {
+  while(txbuffer.size() == 0) step(1);
+  uint8 data = txbuffer[0];
+  txbuffer.remove(0);
+  return data;
+}
+
+//USART -> SNES
+void USART::write(uint8 data) {
+  rxbuffer.append(data);
+}
 
 //USART -> SNES
 uint2 USART::data() {
-  if(rxlength == 0) {
+  if(rxlength == 0 && rxbuffer.size()) {
     data1 = 0;
-    rxdata = usart_read();
+    rxdata = rxbuffer[0];
+    rxbuffer.remove(0);
+    rxlength++;
   } else if(rxlength <= 8) {
     data1 = rxdata & 1;
     rxdata >>= 1;
@@ -43,7 +64,7 @@ void USART::latch(bool data) {
     txdata = (data << 7) | (txdata >> 1);
     txlength++;
   } else {
-    if(data == 1) usart_write(txdata);
+    if(data == 1) txbuffer.append(txdata);
     txlength = 0;
   }
 
@@ -60,16 +81,16 @@ USART::USART(bool port) : Controller(port) {
 
   txlength = 0;
   txdata = 0;
+
+  string filename = interface->path(Cartridge::Slot::Base, "usart.so");
+  if(open_absolute(filename)) {
+    main = sym("usart_main");
+    if(main) create(Controller::Enter, 1000000);
+  }
 }
 
 USART::~USART() {
-}
-
-static uint8 usart_read() {
-  return 0xff;
-}
-
-static void usart_write(uint8 data) {
+  if(opened()) close();
 }
 
 #endif

bsnes/snes/controller/usart/usart.hpp

@@ -1,6 +1,12 @@
 struct USART : Controller, public library {
+  void enter();
+  void usleep(unsigned milliseconds);
+  uint8 read();
+  void write(uint8 data);
+
   uint2 data();
   void latch(bool data);
+
   USART(bool port);
   ~USART();
 
@@ -11,7 +17,11 @@ private:
 
   uint8 rxlength;
   uint8 rxdata;
+  vector<uint8> rxbuffer;
 
   uint8 txlength;
   uint8 txdata;
+  vector<uint8> txbuffer;
+
+  function<void (function<void (unsigned)>, function<uint8 ()>, function<void (uint8)>)> main;
 };