added example of using custom checksums

demo/simple_custom_cksum/Makefile

@@ -0,0 +1,11 @@
+CFILES=../utils.c ../../TinyFrame.c
+INCLDIRS=-I. -I.. -I../..
+CFLAGS=-O0 -ggdb --std=gnu99 -Wno-main -Wno-unused -Wall -Wextra $(CFILES) $(INCLDIRS)
+
+run: test.bin
+	./test.bin
+
+build: test.bin
+
+test.bin: test.c $(CFILES)
+	gcc test.c $(CFLAGS) -o test.bin

demo/simple_custom_cksum/TF_Config.h

@@ -0,0 +1,28 @@
+//
+// Created by MightyPork on 2018/01/26.
+//
+
+#ifndef TF_CONFIG_H
+#define TF_CONFIG_H
+
+#include <stdint.h>
+#include <stdio.h>
+
+#define TF_ID_BYTES     1
+#define TF_LEN_BYTES    2
+#define TF_TYPE_BYTES   1
+#define TF_CKSUM_TYPE TF_CKSUM_CUSTOM8
+#define TF_USE_SOF_BYTE 1
+#define TF_SOF_BYTE     0x01
+typedef uint16_t TF_TICKS;
+typedef uint8_t TF_COUNT;
+#define TF_MAX_PAYLOAD_RX 1024
+#define TF_SENDBUF_LEN 1024
+#define TF_MAX_ID_LST   10
+#define TF_MAX_TYPE_LST 10
+#define TF_MAX_GEN_LST  5
+#define TF_PARSER_TIMEOUT_TICKS 10
+
+#define TF_Error(format, ...) printf("[TF] " format "\n", ##__VA_ARGS__)
+
+#endif //TF_CONFIG_H

demo/simple_custom_cksum/test.c

@@ -0,0 +1,88 @@
+#include <stdio.h>
+#include <string.h>
+#include "../../TinyFrame.h"
+#include "../utils.h"
+
+TinyFrame *demo_tf;
+
+bool do_corrupt = false;
+
+/**
+ * This function should be defined in the application code.
+ * It implements the lowest layer - sending bytes to UART (or other)
+ */
+void TF_WriteImpl(TinyFrame *tf, const uint8_t *buff, uint32_t len)
+{
+    printf("--------------------\n");
+    printf("\033[32mTF_WriteImpl - sending frame:\033[0m\n");
+    
+    uint8_t *xbuff = (uint8_t *)buff;    
+    if (do_corrupt) {
+      printf("(corrupting to test checksum checking...)\n");
+      xbuff[8]++;
+    }
+    
+    dumpFrame(xbuff, len);
+
+    // Send it back as if we received it
+    TF_Accept(tf, xbuff, len);
+}
+
+/** An example listener function */
+TF_Result myListener(TinyFrame *tf, TF_Msg *msg)
+{
+    dumpFrameInfo(msg);
+    return TF_STAY;
+}
+
+TF_Result testIdListener(TinyFrame *tf, TF_Msg *msg)
+{
+    printf("OK - ID Listener triggered for msg!\n");
+    dumpFrameInfo(msg);
+    return TF_CLOSE;
+}
+
+void main(void)
+{
+    TF_Msg msg;
+    const char *longstr = "Lorem ipsum dolor sit amet.";
+
+    // Set up the TinyFrame library
+    demo_tf = TF_Init(TF_MASTER); // 1 = master, 0 = slave
+    TF_AddGenericListener(demo_tf, myListener);
+
+    printf("------ Simulate sending a message --------\n");
+
+    TF_ClearMsg(&msg);
+    msg.type = 0x22;
+    msg.data = (pu8) "Hello TinyFrame";
+    msg.len = 16;
+    TF_Send(demo_tf, &msg);
+    
+    printf("This should fail:\n");
+    
+    // test checksums are tested
+    do_corrupt = true;    
+    msg.type = 0x44;
+    msg.data = (pu8) "Hello2";
+    msg.len = 7;
+    TF_Send(demo_tf, &msg);
+}
+
+
+// a made up custom checksum - just to test it's used and works
+
+TF_CKSUM TF_CksumStart(void)
+{
+    return 0;
+}
+
+TF_CKSUM TF_CksumAdd(TF_CKSUM cksum, uint8_t byte)
+{
+    return cksum ^ byte + 1;
+}
+
+TF_CKSUM TF_CksumEnd(TF_CKSUM cksum)
+{
+    return ~cksum ^ 0xA5;
+}