Initial commit

1 files changed, 59 insertions, 0 deletions

diff --git a/src/input.c b/src/input.c
new file mode 100644
index 0000000..db306ea
--- /dev/null
+++ b/src/input.c
@@ -0,0 +1,59 @@
+#include <hardware.h>
+#include <tty.h>
+#include <stdint.h>
+#include <input.h>
+
+enum encoder_state {
+	START,
+	CW_START,
+	CW_NEXT,
+	CW_FINAL,
+	CCW_START,
+	CCW_NEXT,
+	CCW_FINAL,
+	CW = 0x10,
+	CCW = 0x20
+};
+
+/* State machine to keep track of encoder */
+static const uint8_t encoder_table[7][4] = {
+	/*              00        01         10         11*/
+	[START]     = { START,    CCW_START, CW_START,  START       },
+	[CCW_START] = { CCW_NEXT, CCW_START, START,     START       },
+	[CCW_NEXT]  = { CCW_NEXT, CCW_START, CCW_FINAL, START       },
+	[CCW_FINAL] = { CCW_NEXT, START,     CCW_FINAL, START | CCW },
+	[CW_START]  = { CW_NEXT,  START,     CW_START,  START       },
+	[CW_NEXT]   = { CW_NEXT,  CW_FINAL,  CW_START,  START       },
+	[CW_FINAL]  = { CW_NEXT,  CW_FINAL,  START,     START | CW  }
+};
+
+struct fifo input_fifo = {0, 0, {0}};
+
+void
+input_event(void) __critical __interrupt(4)
+{
+	if ((port_b_data & 0x03) != 0x03) {
+		// Encoder
+		uint8_t state = START;
+		uint8_t encoder;
+		uint8_t next_state;
+
+		do {
+			encoder = port_b_data & 0x03;
+			next_state = encoder_table[state][encoder];
+			state = next_state & 0x0F;
+		} while (state != START);
+
+		if (next_state == CW || next_state == CCW)
+			fifo_push(&input_fifo, next_state);
+	} else if (port_b_data & 0x7C) {
+		// Key pressed
+		for (int i = 0; i < 5; i++) {
+			uint8_t bit = 1 << (i + 2);
+			uint8_t state = !(port_b_data & bit);
+
+			if (state)
+				fifo_push(&input_fifo, i);
+		}
+	}
+}