From c679426262d49f4591f22a1fd8d41458e233921f Mon Sep 17 00:00:00 2001
From: XANTRONIX Development <dev@xantronix.com>
Date: Wed, 1 Jun 2016 22:30:12 -0500
Subject: [PATCH] *shrug* Gotta commit somethin'

---
 avr/Makefile             |  35 +++++++++----
 avr/{main.c => recv.c}   |   2 -
 avr/send.c               | 106 +++++++++++++++++++++++++++++++++++++++
 avr/uart.c               |   3 +-
 include/tabby/avr/uart.h |   2 +
 5 files changed, 134 insertions(+), 14 deletions(-)
 rename avr/{main.c => recv.c} (99%)
 create mode 100644 avr/send.c

diff --git a/avr/Makefile b/avr/Makefile
index 66ea28a..7ade12e 100644
--- a/avr/Makefile
+++ b/avr/Makefile
@@ -1,11 +1,14 @@
 include ../mk/build.mk
 
+CLOCK_SPEED	= 16000000L
+
 INCLUDE_PATH	= ../include
 HEADER_SUBDIR	= tabby
 CROSS		= avr-
 
 CC		= $(CROSS)gcc
-CFLAGS		= $(CGFLAGS) -Wall -Os -mmcu=atmega328p -I$(INCLUDE_PATH)
+CFLAGS		= $(CGFLAGS) -Wall -Os -mmcu=atmega328p -I$(INCLUDE_PATH) \
+		  -DF_CPU=$(CLOCK_SPEED)
 LDFLAGS		=
 
 OBJCOPY		= $(CROSS)objcopy
@@ -20,21 +23,33 @@ HEADERS_BUILD	= $(HEADERS_LOCAL) \
 		  $(addprefix $(INCLUDE_PATH)/$(HEADER_SUBDIR)/,$(HEADERS))
 
 HEADERS		= avr/buffer.h avr/uart.h link.h
-OBJS		= main.o uart.o
+OBJS		= send.o recv.o uart.o
 
-IMAGE_NAME	= tabby
-IMAGE_ELF	= $(IMAGE_NAME).elf
-IMAGE_BIN	= $(IMAGE_NAME).bin
+RECV_NAME	= recv
+RECV_BIN	= $(RECV_NAME).bin
+RECV_ELF	= $(RECV_NAME).elf
+RECV_OBJS	= recv.o uart.o
+
+SEND_NAME	= send
+SEND_BIN	= $(SEND_NAME).bin
+SEND_ELF	= $(SEND_NAME).elf
+SEND_OBJS	= send.o uart.o
+
+IMAGES_BIN	= $(RECV_BIN) $(SEND_BIN)
+IMAGES_ELF	= $(RECV_ELF) $(SEND_ELF)
 
 RM		= /bin/rm
 
-all: $(IMAGE_BIN)
+all: $(IMAGES_BIN)
 
-$(IMAGE_BIN): $(IMAGE_ELF)
+$(IMAGES_BIN): %.bin: %.elf
 	$(OBJCOPY) $(OBJCOPY_FLAGS) -O binary $< $@
 
-$(IMAGE_ELF): $(OBJS)
-	$(CC) $(CFLAGS) $(OBJS) -o $@
+$(SEND_ELF): $(SEND_OBJS)
+	$(CC) $(CFLAGS) $(SEND_OBJS) -o $@
+
+$(RECV_ELF): $(RECV_OBJS)
+	$(CC) $(CFLAGS) $(RECV_OBJS) -o $@
 
 $(OBJS): %.o: %.c $(HEADERS_BUILD)
 	$(CC) $(CFLAGS) -c $<
@@ -43,4 +58,4 @@ flash: $(IMAGE_BIN)
 	$(AVRDUDE) $(AVRDUDE_FLAGS) -U flash:w:$(IMAGE_BIN):r
 
 clean:
-	$(RM) -f $(IMAGE_BIN) $(IMAGE_ELF) $(OBJS)
+	$(RM) -f $(IMAGES_BIN) $(IMAGES_ELF) $(OBJS)
diff --git a/avr/main.c b/avr/recv.c
similarity index 99%
rename from avr/main.c
rename to avr/recv.c
index 5f81dda..c6f3260 100644
--- a/avr/main.c
+++ b/avr/recv.c
@@ -1,5 +1,3 @@
-#include <stdio.h>
-
 #include <avr/io.h>
 #include <avr/interrupt.h>
 #include <avr/sleep.h>
diff --git a/avr/send.c b/avr/send.c
new file mode 100644
index 0000000..7411ded
--- /dev/null
+++ b/avr/send.c
@@ -0,0 +1,106 @@
+#include <avr/io.h>
+#include <avr/interrupt.h>
+#include <util/delay.h>
+
+#include <tabby/printer.h>
+#include <tabby/avr/uart.h>
+
+#define TIMER0_INTERVAL 1953
+
+static volatile uint8_t bits      = 0;
+static volatile uint8_t value_in  = 0x00; /* Data coming in from Game Boy */
+static volatile uint8_t value_out = 0x00; /* Data going out to Game Boy */
+
+static volatile tabby_printer_packet header = {
+    .type        = 0,
+    .compression = 0,
+    .size        = 0
+};
+
+static volatile uint16_t i = 0,
+                         b = 0;
+
+/*
+ * Internal clock source interrupt vector
+ */
+ISR(TIMER0_COMPB_vect) {
+    value_in >>= 1;
+
+    PORTB |= (1 << PORTB5);
+
+    if (PORTB & (1 << PORTB4)) {
+        value_in |= 0x80;
+    }
+
+    if (value_out & 0x80) {
+        PORTB |=  (1 << PORTB3);
+    } else {
+        PORTB &= ~(1 << PORTB3);
+    }
+
+    value_out <<= 1;
+
+    if (--bits == 0) {
+        bits = 8;
+    }
+
+    /*
+     * Chill out for 60µsec, then ride out the rest of the time until the next
+     * interrupt with a high as fuck SCK
+     */
+    _delay_us(60);
+
+    PORTB &= ~(1 << PORTB5);
+}
+
+static void clock_setup() {
+    /*
+     * Configure MISO as output
+     */
+    DDRB |= (1 << DDB4);
+
+    /*
+     * Configure MOSI as input
+     */
+    DDRB &= ~(1 << DDB3);
+
+    /*
+     * Configure SCK pin as output
+     */
+    DDRB |= (1 << DDB5);
+
+    /*
+     * Enable timer interrupt vector
+     */
+    TIMSK0 = (1 << TOIE1);
+
+    /*
+     * Reset timer counter to zero
+     */
+    TCNT1 = 0;
+
+    /*
+     * Set timer interval
+     */
+    OCR1A = TIMER0_INTERVAL;
+
+    /*
+     * Set timer clock divider to 1/1
+     */
+    TCCR1B = (1 << CS10);
+}
+
+int main() {
+    uart_init();
+
+    clock_setup();
+
+    sei();
+
+    while (1) {
+        uint8_t c = uart_getchar(NULL);
+
+    }
+
+    return 0;
+}
diff --git a/avr/uart.c b/avr/uart.c
index 2397d10..22c512f 100644
--- a/avr/uart.c
+++ b/avr/uart.c
@@ -5,8 +5,7 @@
 
 #include <tabby/avr/uart.h>
 
-#define F_CPU 16000000UL
-#define BAUD  TABBY_AVR_UART_BAUD
+#define BAUD TABBY_AVR_UART_BAUD
 
 #include <util/setbaud.h>
 
diff --git a/include/tabby/avr/uart.h b/include/tabby/avr/uart.h
index 55c34a1..0db78ba 100644
--- a/include/tabby/avr/uart.h
+++ b/include/tabby/avr/uart.h
@@ -1,6 +1,8 @@
 #ifndef _TABBY_AVR_UART_H
 #define _TABBY_AVR_UART_H
 
+#include <stdio.h>
+
 #define TABBY_AVR_UART_BAUD 57600
 
 void uart_init();