From bec3721e463d469d833e176133c693cca615a40e Mon Sep 17 00:00:00 2001
From: Dreaded_X <tim.huizinga@gmail.com>
Date: Wed, 30 Dec 2020 03:22:45 +0100
Subject: [PATCH] Initial commit

---
 .gitignore           |   3 +
 Makefile             |  39 ++++++++
 generate_scancode.py | 147 +++++++++++++++++++++++++++
 include/fifo.h       |  19 ++++
 include/keyboard.h   |  15 +++
 include/scancode.h   |   9 ++
 src/fifo.c           |  37 +++++++
 src/keyboard.c       | 231 +++++++++++++++++++++++++++++++++++++++++++
 src/main.c           |  53 ++++++++++
 src/scancode.c       |  10 ++
 10 files changed, 563 insertions(+)
 create mode 100644 .gitignore
 create mode 100644 Makefile
 create mode 100644 generate_scancode.py
 create mode 100644 include/fifo.h
 create mode 100644 include/keyboard.h
 create mode 100644 include/scancode.h
 create mode 100644 src/fifo.c
 create mode 100644 src/keyboard.c
 create mode 100644 src/main.c
 create mode 100644 src/scancode.c

diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..e8de739
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,3 @@
+.build/
+.clangd
+compile_commands.json
diff --git a/Makefile b/Makefile
new file mode 100644
index 0000000..0bcdd2e
--- /dev/null
+++ b/Makefile
@@ -0,0 +1,39 @@
+OBJCOPY = avr-objcopy
+CC = avr-gcc
+BUILD = .build
+TARGET = main
+
+OPT = s
+CFLAGS = -Wall -Wextra -std=c18 -O$(OPT) -ffunction-sections -fdata-sections -MMD -flto -fno-fat-lto-objects -mmcu=atmega328p -DF_CPU=16000000L -Iinclude
+LDFLAGS = -Wall -Wextra -O$(OPT) -flto -fuse-linker-plugin -Wl,--gc-sections -mmcu=atmega328p
+
+SRC = \
+src/main.c \
+src/keyboard.c \
+src/fifo.c \
+src/scancode.c
+
+OBJ = $(addprefix $(BUILD)/, $(notdir $(SRC:.c=.o)))
+vpath %.c $(sort $(dir $(SRC)))
+
+.PHONY: all clean
+
+all: $(BUILD) $(BUILD)/$(TARGET).bin
+
+%.hex: %.elf | $(BUILD)
+	$(OBJCOPY) -O ihex -R .eeprom $< $@
+
+%.bin: %.hex | $(BUILD)
+	$(OBJCOPY) -I ihex -O binary $< $@
+
+$(BUILD)/%.o: %.c Makefile | $(BUILD)
+	$(CC) -c $(CFLAGS) $< -o $@
+
+$(BUILD)/$(TARGET).elf: $(OBJ) Makefile
+	$(CC) $(LDFLAGS) $(OBJ) -o $@
+
+$(BUILD):
+	mkdir $@
+
+clean:
+	rm -fr $(BUILD)
diff --git a/generate_scancode.py b/generate_scancode.py
new file mode 100644
index 0000000..b4a1655
--- /dev/null
+++ b/generate_scancode.py
@@ -0,0 +1,147 @@
+#!/usr/bin/env python3
+
+scancode = [[0]*128, [0]*128]
+
+scancode[0][0x0D] = '\t'
+scancode[0][0x0E] = '`'
+scancode[0][0x15] = 'q'
+scancode[0][0x16] = '1'
+scancode[0][0x1A] = 'z'
+scancode[0][0x1B] = 's'
+scancode[0][0x1C] = 'a'
+scancode[0][0x1D] = 'w'
+scancode[0][0x1E] = '2'
+scancode[0][0x21] = 'c'
+scancode[0][0x22] = 'x'
+scancode[0][0x23] = 'd'
+scancode[0][0x24] = 'e'
+scancode[0][0x25] = '4'
+scancode[0][0x26] = '3'
+scancode[0][0x29] = ' '
+scancode[0][0x2A] = 'v'
+scancode[0][0x2B] = 'f'
+scancode[0][0x2C] = 't'
+scancode[0][0x2D] = 'r'
+scancode[0][0x2E] = '5'
+scancode[0][0x31] = 'n'
+scancode[0][0x32] = 'b'
+scancode[0][0x33] = 'h'
+scancode[0][0x34] = 'g'
+scancode[0][0x35] = 'y'
+scancode[0][0x36] = '6'
+scancode[0][0x3A] = 'm'
+scancode[0][0x3B] = 'j'
+scancode[0][0x3C] = 'u'
+scancode[0][0x3D] = '7'
+scancode[0][0x3E] = '8'
+scancode[0][0x41] = ','
+scancode[0][0x42] = 'k'
+scancode[0][0x43] = 'i'
+scancode[0][0x44] = 'o'
+scancode[0][0x45] = '0'
+scancode[0][0x46] = '9'
+scancode[0][0x49] = '.'
+scancode[0][0x4A] = '/'
+scancode[0][0x4B] = 'l'
+scancode[0][0x4C] = ';'
+scancode[0][0x4D] = 'p'
+scancode[0][0x4E] = '-'
+scancode[0][0x52] = '\''
+scancode[0][0x54] = '['
+scancode[0][0x55] = '='
+scancode[0][0x5A] = '\r'
+scancode[0][0x5B] = ']'
+scancode[0][0x5D] = '\\'
+scancode[0][0x66] = 0x08
+scancode[0][0x69] = '1'
+scancode[0][0x6B] = '2'
+scancode[0][0x6C] = '7'
+scancode[0][0x70] = '0'
+scancode[0][0x71] = '.'
+scancode[0][0x72] = '2'
+scancode[0][0x73] = '5'
+scancode[0][0x74] = '6'
+scancode[0][0x75] = '8'
+scancode[0][0x76] = 0x1B
+scancode[0][0x79] = '+'
+scancode[0][0x7A] = '3'
+scancode[0][0x7B] = '-'
+scancode[0][0x7C] = '*'
+scancode[0][0x7D] = '9'
+
+scancode[1][0x0D] = '\t'
+scancode[1][0x0E] = '~'
+scancode[1][0x15] = 'Q'
+scancode[1][0x16] = '!'
+scancode[1][0x1A] = 'Z'
+scancode[1][0x1B] = 'S'
+scancode[1][0x1C] = 'A'
+scancode[1][0x1D] = 'W'
+scancode[1][0x1E] = '@'
+scancode[1][0x21] = 'C'
+scancode[1][0x22] = 'X'
+scancode[1][0x23] = 'D'
+scancode[1][0x24] = 'E'
+scancode[1][0x25] = '$'
+scancode[1][0x26] = '#'
+scancode[1][0x29] = ' '
+scancode[1][0x2A] = 'V'
+scancode[1][0x2B] = 'F'
+scancode[1][0x2C] = 'T'
+scancode[1][0x2D] = 'R'
+scancode[1][0x2E] = '%'
+scancode[1][0x31] = 'N'
+scancode[1][0x32] = 'B'
+scancode[1][0x33] = 'H'
+scancode[1][0x34] = 'G'
+scancode[1][0x35] = 'Y'
+scancode[1][0x36] = '^'
+scancode[1][0x3A] = 'M'
+scancode[1][0x3B] = 'J'
+scancode[1][0x3C] = 'U'
+scancode[1][0x3D] = '&'
+scancode[1][0x3E] = '*'
+scancode[1][0x41] = '<'
+scancode[1][0x42] = 'K'
+scancode[1][0x43] = 'I'
+scancode[1][0x44] = 'O'
+scancode[1][0x45] = ')'
+scancode[1][0x46] = '('
+scancode[1][0x49] = '>'
+scancode[1][0x4A] = '?'
+scancode[1][0x4B] = 'L'
+scancode[1][0x4C] = ':'
+scancode[1][0x4D] = 'P'
+scancode[1][0x4E] = '_'
+scancode[1][0x52] = '"'
+scancode[1][0x54] = '{'
+scancode[1][0x55] = '+'
+scancode[1][0x5A] = '\r'
+scancode[1][0x5B] = '}'
+scancode[1][0x5D] = '|'
+scancode[1][0x66] = 0X08
+scancode[1][0x69] = '1'
+scancode[1][0x6B] = '2'
+scancode[1][0x6C] = '7'
+scancode[1][0x70] = '0'
+scancode[1][0x71] = '.'
+scancode[1][0x72] = '2'
+scancode[1][0x73] = '5'
+scancode[1][0x74] = '6'
+scancode[1][0x75] = '8'
+scancode[1][0x76] = 0X1B
+scancode[1][0x79] = '+'
+scancode[1][0x7A] = '3'
+scancode[1][0x7B] = '-'
+scancode[1][0x7C] = '*'
+scancode[1][0x7D] = '9'
+
+print("char scancode[2][128] = {")
+for i in scancode:
+    print("\t{", end="")
+    for j in i:
+        if (type(j) == str):
+            j = ord(j)
+        print(f"0x{j:02x},", end="")
+    print("},")
+print("};")
diff --git a/include/fifo.h b/include/fifo.h
new file mode 100644
index 0000000..7ab2394
--- /dev/null
+++ b/include/fifo.h
@@ -0,0 +1,19 @@
+#ifndef FIFO_h
+#define FIFO_h
+
+#include <stdint.h>
+
+#define FIFO_SIZE 64
+
+struct FIFO {
+	int head;
+	int tail;
+	int size;
+	uint8_t buffer[FIFO_SIZE];
+};
+
+void FIFO_push(volatile struct FIFO* fifo, uint8_t value);
+uint8_t FIFO_pop(volatile struct FIFO* fifo);
+int FIFO_size(volatile struct FIFO* fifo);
+
+#endif
diff --git a/include/keyboard.h b/include/keyboard.h
new file mode 100644
index 0000000..b63841c
--- /dev/null
+++ b/include/keyboard.h
@@ -0,0 +1,15 @@
+#ifndef KEYBOARD_h
+#define KEYBOARD_h
+
+#include <stdint.h>
+
+#define KEYBOARD_CLK 2
+#define KEYBOARD_DATA 7
+
+void send_keyboard_cmd(uint8_t value);
+void queue_keyboard_cmd(uint8_t value);
+void send_keyboard_cmd_queue();
+
+void keyboard_interrupt(void (*callback)(uint8_t));
+
+#endif
diff --git a/include/scancode.h b/include/scancode.h
new file mode 100644
index 0000000..656b6e3
--- /dev/null
+++ b/include/scancode.h
@@ -0,0 +1,9 @@
+#ifndef SCANCODE_H
+#define SCANCODE_H
+
+#include <stdint.h>
+
+void setup_scancode();
+// uint8_t convert_scancode(uint8_t shift, uint8_t code);
+
+#endif
diff --git a/src/fifo.c b/src/fifo.c
new file mode 100644
index 0000000..6653ad0
--- /dev/null
+++ b/src/fifo.c
@@ -0,0 +1,37 @@
+#include "fifo.h"
+
+void FIFO_push(volatile struct FIFO* fifo, uint8_t value) {
+	if (fifo->size == FIFO_SIZE) {
+		return;
+	}
+
+	fifo->size++;
+
+	if (fifo->size > 1) {
+		fifo->tail++;
+		fifo->tail %= FIFO_SIZE;
+	}
+
+	fifo->buffer[fifo->tail] = value;
+}
+
+uint8_t FIFO_pop(volatile struct FIFO* fifo) {
+	if (fifo->size == 0) {
+		return 0;
+	}
+
+	fifo->size--;
+
+	uint8_t data = fifo->buffer[fifo->head];
+
+	if (fifo->size >= 1) {
+		fifo->head++;
+		fifo->head %= FIFO_SIZE;
+	}
+
+	return data;
+}
+
+int FIFO_size(volatile struct FIFO* fifo) {
+	return fifo->size;
+}
diff --git a/src/keyboard.c b/src/keyboard.c
new file mode 100644
index 0000000..8574007
--- /dev/null
+++ b/src/keyboard.c
@@ -0,0 +1,231 @@
+#include <avr/io.h>
+#include <util/delay.h>
+
+#include "keyboard.h"
+#include "scancode.h"
+#include "fifo.h"
+
+volatile struct {
+	struct FIFO buffer;
+
+	uint8_t sending : 1;
+	uint16_t value;
+	uint8_t counter;
+
+	struct {
+		uint8_t shift : 1;
+		uint8_t caps_lock : 1;
+		uint8_t ctrl : 1;
+	} modifier;
+
+	uint8_t released : 1;
+} keyboard = {0};
+
+// Send a command to the keyboard (BLOCKS)
+void send_keyboard_cmd(uint8_t value) {
+	// Pull clock low
+	DDRD |= (1<<KEYBOARD_CLK);
+	PORTD &= ~(1<<KEYBOARD_CLK);
+
+	_delay_ms(1);
+
+	// Pull data low
+	DDRD |= (1<<KEYBOARD_DATA);
+	PORTD &= ~(1<<KEYBOARD_DATA);
+
+	// Release clock
+	DDRD &= ~(1<<KEYBOARD_CLK);
+
+	keyboard.sending = 1;
+	keyboard.value = value;
+
+	while (keyboard.sending) {};
+}
+
+// Add keyboard command to the queue
+void queue_keyboard_cmd(uint8_t value) {
+	FIFO_push(&keyboard.buffer, value);
+}
+
+// Send queued command
+void send_keyboard_cmd_queue() {
+	while (FIFO_size(&keyboard.buffer)) {
+		send_keyboard_cmd(FIFO_pop(&keyboard.buffer));
+	}
+}
+
+// Calculate parity
+uint8_t parity(uint8_t value) {
+	value ^= value >> 4;
+	value ^= value >> 2;
+	value ^= value >> 1;
+
+	return (~value) & 1;
+}
+
+void receive_scancode_bit(void (*callback)(uint8_t)) {
+	keyboard.value |= ((PIND >> KEYBOARD_DATA) & 1) << keyboard.counter;
+	keyboard.counter++;
+
+	// Check that the first bit is 0
+	if (keyboard.counter == 1 && keyboard.value & 1) {
+		keyboard.counter = 0;
+		keyboard.value = 0;
+
+		return;
+	}
+
+	// Check the parity
+	if (keyboard.counter == 10 && parity(keyboard.value >> 1) != ((keyboard.value >> 9) & 1)) {
+		keyboard.counter = 0;
+		keyboard.value = 0;
+
+		return;
+	}
+
+	// Check that the last bit is 1
+	if (keyboard.counter == 11 && !((keyboard.value >> 10) & 1)) {
+		keyboard.counter = 0;
+		keyboard.value = 0;
+
+		return;
+	}
+
+	// Process the scancode
+	if (keyboard.counter == 11) {
+		uint8_t value = keyboard.value >> 1;
+
+		keyboard.counter = 0;
+		keyboard.value = 0;
+
+		switch (value) {
+			// Left and right shift
+			case 18:
+			case 89:
+				keyboard.modifier.shift = !keyboard.released;
+				keyboard.released = 0;
+				break;
+
+				// Caps lock
+			case 0x58:
+				if (!keyboard.released) {
+					keyboard.modifier.caps_lock = !keyboard.modifier.caps_lock;
+
+					queue_keyboard_cmd(0xED);
+					queue_keyboard_cmd(keyboard.modifier.caps_lock << 2);
+				}
+				keyboard.released = 0;
+				break;
+
+				// Left ctrl
+			case 0x14:
+				keyboard.modifier.ctrl = !keyboard.released;
+				keyboard.released = 0;
+				break;
+
+			case 240:
+				keyboard.released = 1;
+				break;
+
+			default:
+				if (!keyboard.released) {
+					char c = convert_scancode(keyboard.modifier.shift, value & 127);
+
+					if (keyboard.modifier.caps_lock && !keyboard.modifier.shift && c >= 'a' && c <= 'z') {
+						c -= 0x20;
+					}
+
+					if (keyboard.modifier.ctrl) {
+						switch (c) {
+							case 'c':
+								c = 0x03;
+								break;
+
+							case 'e':
+								c = 0x05;
+								break;
+
+							case 'p':
+								c = 0x10;
+								break;
+
+							case 'r':
+								c = 0x12;
+								break;
+
+							case 's':
+								c = 0x13;
+								break;
+
+							case 'u':
+								c = 0x15;
+								break;
+
+							case 'x':
+								c = 0x18;
+								break;
+
+							case 'z':
+								c = 0x1A;
+								break;
+
+							default:
+								c = 0x00;
+								break;
+						}
+					}
+
+					if (c) {
+						callback(c);
+					}
+				}
+				keyboard.released = 0;
+				break;
+		}
+	}
+}
+
+void send_cmd_bit() {
+	if (keyboard.counter == 8) {
+		// Send parity
+		if (parity(keyboard.value)) {
+			PORTD |= (1<<KEYBOARD_DATA);
+		} else {
+			PORTD &= ~(1<<KEYBOARD_DATA);
+		}
+
+		++keyboard.counter;
+	} else if (keyboard.counter == 9) {
+		// Release data line
+		PORTD &= ~(1<<KEYBOARD_DATA);
+		DDRD &= ~(1<<KEYBOARD_DATA);
+
+		++keyboard.counter;
+	} else if (keyboard.counter == 10) {
+		// Wait for data to go low as ack
+		if (!((PIND >> KEYBOARD_DATA) & 1)) {
+			keyboard.counter = 0;
+			keyboard.value = 0;
+			keyboard.sending = 0;
+		}
+	} else {
+		// Send bit
+		if ((keyboard.value >> keyboard.counter) & 1) {
+			PORTD |= (1<<KEYBOARD_DATA);
+		} else {
+			PORTD &= ~(1<<KEYBOARD_DATA);
+		}
+
+		++keyboard.counter;
+	}
+}
+
+void keyboard_interrupt(void (*callback)(uint8_t)) {
+	if (!keyboard.sending && PIND & (1<<KEYBOARD_CLK)) {
+		receive_scancode_bit(callback);
+	}
+
+	if (keyboard.sending && !(PIND>>KEYBOARD_CLK & 1)) {
+		send_cmd_bit();
+	}
+}
diff --git a/src/main.c b/src/main.c
new file mode 100644
index 0000000..c76ff59
--- /dev/null
+++ b/src/main.c
@@ -0,0 +1,53 @@
+#include <avr/io.h>
+#include <avr/interrupt.h>
+#include <util/delay.h>
+#include <stddef.h>
+
+#include "scancode.h"
+#include "keyboard.h"
+
+#define CLK 4
+#define DATA 5
+
+// Clock the value to 74164
+void write_value(uint8_t value) {
+	for (uint8_t i = 0; i < 8; ++i) {
+		uint8_t bit = (value >> i) & 1;
+		PORTD |= (1<<CLK) | (bit<<DATA);
+		PORTD &= ~((1<<CLK) | (bit<<DATA));
+	}
+}
+
+ISR(PCINT2_vect) {
+	keyboard_interrupt(write_value);
+}
+
+int main() {
+	// Configure pins as output
+	DDRD |= (1<<CLK) | (1<<DATA);
+
+	DDRD &= ~((1<<KEYBOARD_CLK) | (1<<KEYBOARD_DATA));
+
+	// interrupt
+	PCMSK2 |= (1<<PCINT18);
+	PCICR |= (1<<PCIE2);
+
+	write_value(0);
+
+	sei();
+
+	// Wait for the keyboard to be ready
+	_delay_ms(1000);
+	// Reset the keyboard
+	send_keyboard_cmd(0xFF);
+
+	_delay_ms(1000);
+
+	// Set the keyboard repeat rate (and delay)
+	send_keyboard_cmd(0xF3);
+	send_keyboard_cmd(0x00 | (1<<5) | (1<<4));
+
+	for (;;) {
+		send_keyboard_cmd_queue();
+	}
+}
diff --git a/src/scancode.c b/src/scancode.c
new file mode 100644
index 0000000..5371561
--- /dev/null
+++ b/src/scancode.c
@@ -0,0 +1,10 @@
+#include "scancode.h"
+
+char scancode[2][128] = {
+	{0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x09,0x60,0x00,0x00,0x00,0x00,0x00,0x00,0x71,0x31,0x00,0x00,0x00,0x7a,0x73,0x61,0x77,0x32,0x00,0x00,0x63,0x78,0x64,0x65,0x34,0x33,0x00,0x00,0x20,0x76,0x66,0x74,0x72,0x35,0x00,0x00,0x6e,0x62,0x68,0x67,0x79,0x36,0x00,0x00,0x00,0x6d,0x6a,0x75,0x37,0x38,0x00,0x00,0x2c,0x6b,0x69,0x6f,0x30,0x39,0x00,0x00,0x2e,0x2f,0x6c,0x3b,0x70,0x2d,0x00,0x00,0x00,0x27,0x00,0x5b,0x3d,0x00,0x00,0x00,0x00,0x0d,0x5d,0x00,0x5c,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x08,0x00,0x00,0x31,0x00,0x32,0x37,0x00,0x00,0x00,0x30,0x2e,0x32,0x35,0x36,0x38,0x1b,0x00,0x00,0x2b,0x33,0x2d,0x2a,0x39,0x00,0x00,},
+	{0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x09,0x7e,0x00,0x00,0x00,0x00,0x00,0x00,0x51,0x21,0x00,0x00,0x00,0x5a,0x53,0x41,0x57,0x40,0x00,0x00,0x43,0x58,0x44,0x45,0x24,0x23,0x00,0x00,0x20,0x56,0x46,0x54,0x52,0x25,0x00,0x00,0x4e,0x42,0x48,0x47,0x59,0x5e,0x00,0x00,0x00,0x4d,0x4a,0x55,0x26,0x2a,0x00,0x00,0x3c,0x4b,0x49,0x4f,0x29,0x28,0x00,0x00,0x3e,0x3f,0x4c,0x3a,0x50,0x5f,0x00,0x00,0x00,0x22,0x00,0x7b,0x2b,0x00,0x00,0x00,0x00,0x0d,0x7d,0x00,0x7c,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x08,0x00,0x00,0x31,0x00,0x32,0x37,0x00,0x00,0x00,0x30,0x2e,0x32,0x35,0x36,0x38,0x1b,0x00,0x00,0x2b,0x33,0x2d,0x2a,0x39,0x00,0x00,},
+};
+
+uint8_t convert_scancode(uint8_t shift, uint8_t code) {
+	return scancode[shift][code];
+}