From 5da22fff03e55183c5f37e393348b7be83ae1a4d Mon Sep 17 00:00:00 2001
From: LongHairedHacker <sebastian@sebastians-site.de>
Date: Sun, 20 Nov 2016 02:24:07 +0100
Subject: [PATCH] Started to seperate AVR specific code from SSS7 core

---
 software/AVR8/sss7.c | 33 ++++++++++++++++++++++++---------
 software/AVR8/sss7.h |  6 ++++--
 software/AVR8/uart.c | 12 +++++++++++-
 software/AVR8/uart.h | 11 ++++++++++-
 4 files changed, 49 insertions(+), 13 deletions(-)

diff --git a/software/AVR8/sss7.c b/software/AVR8/sss7.c
index 33de007..5f36dac 100644
--- a/software/AVR8/sss7.c
+++ b/software/AVR8/sss7.c
@@ -1,9 +1,9 @@
 #include "sss7.h"
 
-#include <avr/interrupt.h>
-#include <util/crc16.h>
 #include <string.h>
 
+#include "uart.h"
+
 volatile enum sss7State sss7_state;
 
 uint8_t sss7_rx_buffer[SSS7_RX_BUFFER_COUNT][SSS7_PAYLOAD_SIZE];
@@ -18,6 +18,7 @@ volatile uint8_t sss7_tx_failed;
 uint8_t sss7_tx_last_byte;
 uint8_t sss7_tx_last_ack;
 
+
 void sss7_init(void) {
 	sss7_state = SSS7_IDLE;
 
@@ -33,20 +34,34 @@ void sss7_init(void) {
 	PORTB |= (1 << PB2) | (1 << PB3);
 }
 
+
 static inline uint8_t sss7_payload_crc(uint8_t buffer[SSS7_PAYLOAD_SIZE]) {
 	uint8_t crc = 0;
-	for(uint8_t i = 0; i < SSS7_PAYLOAD_SIZE; i++) {
-		crc = _crc_ibutton_update(crc, buffer[i]);
+
+	for(uint8_t byte = 0; byte < SSS7_PAYLOAD_SIZE; byte++) {
+		crc = crc ^ buffer[byte];
+		for (uint8_t bit = 0; bit < 8; bit++)
+		{
+			if (crc & 0x01) {
+				crc = (crc >> 1) ^ 0x8C;
+			}
+			else {
+				crc >>= 1;
+			}
+		}
 	}
+	
 	return crc;
 }
 
+
 static inline void sss7_send_byte(uint8_t byte) {
 	sss7_tx_last_ack = 0;
 	sss7_tx_last_byte = byte;
-	UDR = byte;
+	uart_put_byte(byte);
 }
 
+
 void sss7_send(uint8_t msg[SSS7_PAYLOAD_SIZE]) {
 	// Check that we can send, because we will overwritte the buffer
 	if(sss7_state != SSS7_IDLE) {
@@ -66,8 +81,8 @@ void sss7_send(uint8_t msg[SSS7_PAYLOAD_SIZE]) {
 }
 
 
-ISR(USART_RXC_vect) {
-	uint8_t byte = UDR;
+void sss7_process_rx(void) {
+	uint8_t byte = uart_get_byte();
 	uint8_t crc = 0;
 
 	switch(sss7_state) {
@@ -121,8 +136,8 @@ ISR(USART_RXC_vect) {
 	}
 }
 
-ISR(USART_TXC_vect) {
 
+void sss7_process_tx(void) {
 	if(sss7_tx_last_ack) {
 		uint8_t byte;
 		switch(sss7_state) {
@@ -155,9 +170,9 @@ ISR(USART_TXC_vect) {
 		sss7_tx_failed = 1;
 		sss7_state = SSS7_IDLE;
 	}
-
 }
 
+
 void sss7_get_received(uint8_t msg[SSS7_PAYLOAD_SIZE]) {
 	if(sss7_has_received()) {
 		memcpy(msg, sss7_rx_buffer[sss7_rx_oldest_buffer], SSS7_PAYLOAD_SIZE);
diff --git a/software/AVR8/sss7.h b/software/AVR8/sss7.h
index 793207e..fbcf317 100644
--- a/software/AVR8/sss7.h
+++ b/software/AVR8/sss7.h
@@ -24,6 +24,10 @@ extern volatile uint8_t sss7_tx_failed;
 extern uint8_t sss7_rx_active_buffer;
 extern uint8_t sss7_rx_oldest_buffer;
 
+void sss7_process_rx(void);
+void sss7_process_tx(void);
+
+
 void sss7_init(void);
 
 static inline uint8_t sss7_can_send(void) {
@@ -40,8 +44,6 @@ static inline uint8_t sss7_has_received(void) {
 	return sss7_rx_oldest_buffer < sss7_rx_active_buffer;
 }
 
-
-
 void sss7_get_received(uint8_t msg[SSS7_PAYLOAD_SIZE]);
 
 #endif
diff --git a/software/AVR8/uart.c b/software/AVR8/uart.c
index f7c09fc..3b1b427 100644
--- a/software/AVR8/uart.c
+++ b/software/AVR8/uart.c
@@ -1,6 +1,7 @@
 #include "uart.h"
 
-#include <avr/io.h>
+#include <avr/interrupt.h>
+#include <util/crc16.h>
 
 #include "sss7.h"
 
@@ -23,3 +24,12 @@ void uart_init(void) {
 
 	UCSRB |= (1 << TXCIE) | (1 << RXCIE);  // enable tx and rx interrupts
 }
+
+
+ISR(USART_RXC_vect) {
+	sss7_process_rx();
+}
+
+ISR(USART_TXC_vect) {
+	sss7_process_tx();
+}
diff --git a/software/AVR8/uart.h b/software/AVR8/uart.h
index 5813d24..1f6c59d 100644
--- a/software/AVR8/uart.h
+++ b/software/AVR8/uart.h
@@ -1,7 +1,7 @@
 #ifndef _UART_H_
 #define _UART_H_
 
-
+#include <avr/io.h>
 
 #define BAUD 9600UL
 
@@ -17,4 +17,13 @@
 
 void uart_init(void);
 
+static inline uint8_t uart_get_byte(void) {
+    uint8_t byte = UDR;
+    return byte;
+}
+
+static inline void uart_put_byte(uint8_t byte) {
+    UDR = byte;
+}
+
 #endif