From 2f64ad5efccf511e53f0e94de96865c3d0884b7e Mon Sep 17 00:00:00 2001
From: Starport75 <weber.austint@gmail.com>
Date: Wed, 14 Jun 2023 21:12:58 -0500
Subject: [PATCH] Almost working SPI

---
 include/LinkGPIO.h       | 82 ++++++++++++++++++++++++++++++++++++++++
 include/gameboy_colour.h |  6 ++-
 source/debug.cpp         |  1 +
 source/main.cpp          |  4 ++
 4 files changed, 92 insertions(+), 1 deletion(-)
 create mode 100644 include/LinkGPIO.h

diff --git a/include/LinkGPIO.h b/include/LinkGPIO.h
new file mode 100644
index 0000000..ca97511
--- /dev/null
+++ b/include/LinkGPIO.h
@@ -0,0 +1,82 @@
+#ifndef LINK_GPIO_H
+#define LINK_GPIO_H
+
+// --------------------------------------------------------------------------
+// A General Purpose Input-Output handler for the Link Port.
+// --------------------------------------------------------------------------
+// Usage:
+// - 1) Include this header in your main.cpp file and add:
+//       LinkGPIO* linkGPIO = new LinkGPIO();
+// - 2) Initialize the library with:
+//       linkGPIO->reset();
+// - 3) Write pins by using:
+//       linkGPIO->setMode(LinkGPIO::Pin::SD, LinkGPIO::Direction::OUTPUT);
+//       linkGPIO->writePin(LinkGPIO::Pin::SD, true);
+// - 4) Read pins by using:
+//       linkGPIO->setMode(LinkGPIO::Pin::SC, LinkGPIO::Direction::INPUT);
+//       bool isHigh = linkGPIO->readPin(LinkGPIO::Pin::SC);
+// - 5) Subscribe to SI falling:
+//       linkGPIO->setSIInterrupts(true);
+//       // (when SI changes from high to low, an IRQ will be generated)
+// --------------------------------------------------------------------------
+// `setMode` restrictions:
+// - always set the SI terminal to an input!
+// --------------------------------------------------------------------------
+
+#include <tonc_core.h>
+
+#define LINK_GPIO_RCNT_GENERAL_PURPOSE (1 << 15)
+#define LINK_GPIO_SIOCNT_GENERAL_PURPOSE 0
+#define LINK_GPIO_BIT_SI_INTERRUPT 8
+#define LINK_GPIO_GET(REG, BIT) ((REG >> BIT) & 1)
+#define LINK_GPIO_SET(REG, BIT, DATA) \
+  if (DATA)                           \
+    LINK_GPIO_SET_HIGH(REG, BIT);     \
+  else                                \
+    LINK_GPIO_SET_LOW(REG, BIT);
+#define LINK_GPIO_SET_HIGH(REG, BIT) REG |= 1 << BIT
+#define LINK_GPIO_SET_LOW(REG, BIT) REG &= ~(1 << BIT)
+
+static volatile char LINK_GPIO_VERSION[] = "LinkGPIO/v5.0.2";
+
+const u8 LINK_GPIO_DATA_BITS[] = {2, 3, 1, 0};
+const u8 LINK_GPIO_DIRECTION_BITS[] = {6, 7, 5, 4};
+
+class LinkGPIO {
+ public:
+  enum Pin { SI, SO, SD, SC };
+  enum Direction { INPUT, OUTPUT };
+
+  void reset() {
+    REG_RCNT = LINK_GPIO_RCNT_GENERAL_PURPOSE;
+    REG_SIOCNT = LINK_GPIO_SIOCNT_GENERAL_PURPOSE;
+  }
+
+  void setMode(Pin pin, Direction direction) {
+    if (pin == Pin::SI && Direction::OUTPUT)
+      return;  // (disabled for safety reasons)
+
+    LINK_GPIO_SET(REG_RCNT, LINK_GPIO_DIRECTION_BITS[pin],
+                  direction == Direction::OUTPUT);
+  }
+
+  Direction getMode(Pin pin) {
+    return Direction(LINK_GPIO_GET(REG_RCNT, LINK_GPIO_DIRECTION_BITS[pin]));
+  }
+
+  bool readPin(Pin pin) {
+    return (REG_RCNT & (1 << LINK_GPIO_DATA_BITS[pin])) != 0;
+  }
+
+  void writePin(Pin pin, bool isHigh) {
+    LINK_GPIO_SET(REG_RCNT, LINK_GPIO_DATA_BITS[pin], isHigh);
+  }
+
+  void setSIInterrupts(bool isEnabled) {
+    LINK_GPIO_SET(REG_RCNT, LINK_GPIO_BIT_SI_INTERRUPT, isEnabled);
+  }
+};
+
+extern LinkGPIO* linkGPIO;
+
+#endif  // LINK_GPIO_H
diff --git a/include/gameboy_colour.h b/include/gameboy_colour.h
index 60f21d8..1b528fb 100644
--- a/include/gameboy_colour.h
+++ b/include/gameboy_colour.h
@@ -4,7 +4,9 @@
 #define GAMEBOY_COLOUR_H_
 
 #include <tonc.h>
-
+#include <string>
+#include "LinkGPIO.h"
+/*
 #define LINK_SPI_NO_DATA 0xffffffff
 #define LINK_SPI_SIOCNT_NORMAL 0
 #define LINK_SPI_BIT_CLOCK 0
@@ -20,11 +22,13 @@
 #define LINK_SPI_SET_LOW(REG, BIT) REG &= ~(1 << BIT)
 
 #define LINK_SPI_SET(REG, BIT, VALUE) VALUE ? LINK_SPI_SET_HIGH(REG, BIT) : LINK_SPI_SET_LOW(REG, BIT)
+*/
 
 
 void setup();
 byte handleIncomingByte(byte in);
 void transferBit(void);
 void loop();
+std::string outHexStr(vu8 inputNum);
 
 #endif /* GAMEBOY_COLOUR_H_ */
diff --git a/source/debug.cpp b/source/debug.cpp
index 3040dc7..f5190fd 100644
--- a/source/debug.cpp
+++ b/source/debug.cpp
@@ -2,6 +2,7 @@
 #include <string>
 #include "mirror.h"
 #include "gba_flash.h"
+#include "debug.h"
 
 char arr[16] = {
 	'0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B', 'C', 'D', 'E', 'F'};
diff --git a/source/main.cpp b/source/main.cpp
index b970c4f..6929580 100644
--- a/source/main.cpp
+++ b/source/main.cpp
@@ -8,6 +8,7 @@
 #include "LinkSPI.h"
 #include "gb_link.h"
 #include "gameboy_colour.h"
+#include "LinkGPIO.h"
 
 // This file is autogenerated from the file in the graphics folder
 #include "metr.h"
@@ -76,6 +77,9 @@ void load_sprite(void)
 
 int main(void)
 {
+
+	linkGPIO->reset();
+
 	REG_DISPCNT = DCNT_MODE0 | DCNT_BG0 | DCNT_OBJ | DCNT_OBJ_1D;
   	tte_init_se_default(0, BG_CBB(0) | BG_SBB(31));