From ba45fbbead04ce1cf515e33a32f277c84d9e7334 Mon Sep 17 00:00:00 2001
From: k2-alfadhala <khalid2.al-fadhala@live.uwe.ac.uk>
Date: Sun, 13 Apr 2025 15:42:39 +0000
Subject: [PATCH] prtocol.c
---
protocol.c | 68 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 68 insertions(+)
create mode 100644 protocol.c
diff --git a/protocol.c b/protocol.c
new file mode 100644
index 0000000..3190624
--- /dev/null
+++ b/protocol.c
@@ -0,0 +1,68 @@
+#include "protocol.h"
+#include "usb_serial.h"
+#include <string.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+void packet_init(Packet *pkt, uint8_t *data, size_t len) {
+ pkt->start = 0xAAAA;
+ pkt->type = 1;
+ pkt->length = sizeof(Packet) + len - sizeof(uint8_t*);
+ pkt->seq = 1;
+ pkt->dtype = 1;
+ pkt->data = malloc(len);
+
+ if (pkt->data) {
+ memcpy(pkt->data, data, len);
+ pkt->chk = compute_checksum(pkt->data, len);
+ } else {
+ pkt->chk = 0;
+ }
+}
+
+void packet_free(Packet *pkt) {
+ if (pkt->data) {
+ free(pkt->data);
+ pkt->data = NULL;
+ }
+}
+
+int proto_send(const Packet* pkt) {
+ if (!usb_serial_connected())
+ return -1;
+
+ if (pkt->length > MAX_PAYLOAD_SIZE)
+ return -2;
+
+ uint8_t buf[sizeof(Packet)];
+ memcpy(buf, pkt, sizeof(Packet) - 1);
+ buf[sizeof(Packet) - 1] = compute_checksum(buf, sizeof(Packet) - 1);
+
+ int sent = usb_serial_write(buf, sizeof(Packet));
+ return (sent == sizeof(Packet)) ? sent : -3;
+}
+
+int proto_recv(Packet* pkt, int max_size) {
+ if (max_size < sizeof(Packet))
+ return -1;
+
+ int got = usb_serial_read((uint8_t*)pkt, sizeof(Packet));
+ if (got != sizeof(Packet))
+ return -2;
+
+ if (compute_checksum((uint8_t*)pkt, sizeof(Packet) - 1) != pkt->chk)
+ return -3;
+
+ return got;
+}
+
+void proto_cleanup(void) {
+ usb_serial_cleanup();
+}
+void proto_disconnect(void) {}
+uint8_t compute_checksum(const uint8_t* data, int len) {
+ uint8_t chk = 0;
+ for (int i = 0; i < len; i++)
+ chk ^= data[i];
+ return chk;
+}
--
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