From 0835e1670600776801dc276bc086b585433cf2b4 Mon Sep 17 00:00:00 2001
From: John-Mark Gurney <jmg@funkthat.com>
Date: Sun, 25 Apr 2021 22:58:55 -0700
Subject: [PATCH] add ability to send arbitrary packets that are hex encoded..

---
 main.c | 156 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 156 insertions(+)

diff --git a/main.c b/main.c
index 257c41e..de948a8 100644
--- a/main.c
+++ b/main.c
@@ -2,11 +2,27 @@
 
 #include <strobe_rng_init.h>
 
+#include <string.h>
+
 #include <board.h>
 #include <misc.h>
 #include <radio.h>
 #include <delay.h>
 
+char *
+findeol(char *pos, size_t len)
+{
+
+	while (len) {
+		if (*pos == '\r' || *pos == '\n')
+			return pos;
+		pos++;
+		len--;
+	}
+
+	return NULL;
+}
+
 void
 hexdump(uint8_t *ptr, size_t len)
 {
@@ -60,6 +76,86 @@ RadioEvents_t revents = {
 	.RxError = rxerr,
 };
 
+static uint8_t
+hexchartonib(char s)
+{
+
+	switch (s) {
+	case '0'...'9':
+		return s - '0';
+	case 'a'...'f':
+		return s - 'a' + 10;
+	case 'A'...'F':
+		return s - 'A' + 10;
+	default:
+		return -1;
+	}
+}
+
+static bool
+hexdecode(char *buf, size_t len, uint8_t *out)
+{
+	uint8_t topchr, botchr;
+
+	if (len % 2)
+		return -1;
+
+	/* NB: only needed to silence a bad gcc warning */
+	topchr = -1;
+
+	while (len) {
+		if (len % 2) {
+			/* bottom nibble */
+			botchr = hexchartonib(*buf);
+			if (topchr == -1 || botchr == -1)
+				return false;
+
+			*out = topchr << 4 | botchr;
+			out++;
+		} else {
+			/* top nibble */
+			topchr = hexchartonib(*buf);
+		}
+		len--;
+		buf++;
+	}
+
+	return true;
+}
+
+static const char pktstart[] = "pkt:";
+static const size_t pktstartlen = sizeof pktstart - 1;
+static uint8_t pktbuf[128];
+
+static void
+process_line(char *start, char *end)
+{
+	size_t len;
+
+	/* trim off leading CR/NL */
+	while (start < end && (*start == '\r' || *start == '\n'))
+		start++;
+
+	len = end - start;
+
+	if (len >= pktstartlen && memcmp(start, pktstart, sizeof pktstart - 1) == 0) {
+		start += pktstartlen;
+		len -= pktstartlen;
+
+		if (len % 2) {
+			usb_printf("invalid pkt len\r\n");
+			return;
+		}
+		if (!hexdecode(start, len, pktbuf)) {
+			usb_printf("invalid pkt\r\n");
+			return;
+		}
+		Radio.Send(pktbuf, len / 2);
+		return;
+	}
+	usb_printf("line: %.*s", end - start, start);
+}
+
 int
 main(void)
 {
@@ -148,10 +244,70 @@ main(void)
 	usb_printf("rx(0)...\r\n");
 	Radio.Rx(0);
 
+	char inpbuf[1024];
+	char *lastcheck;
+	char *endchr;
+	int inpbufpos = 0;
+	int cpylen;
+
 loop:
 	BoardLowPowerHandler();
 	if (Radio.IrqProcess != NULL)
 		Radio.IrqProcess();
 
+	/* while we have data */
+	while (CDC_RX_LEN) {
+		/* store last position */
+		lastcheck = &inpbuf[inpbufpos];
+
+		/* calculate how much space left */
+		cpylen = MIN(sizeof inpbuf - inpbufpos, CDC_RX_LEN);
+
+		/* copy into buffer */
+		memcpy(&inpbuf[inpbufpos], CDC_RX_BUFFER, cpylen);
+
+		/* and point to end of buffer */
+		inpbufpos += cpylen;
+
+		do {
+			/* find first end of line characters */
+			endchr = findeol(lastcheck, cpylen);
+
+			if (endchr != NULL) {
+				/* if so, process it */
+				process_line(inpbuf, endchr);
+
+				/* skip end of line char */
+				endchr++;
+
+				/* move remaining buffer to the beginning */
+				memmove(inpbuf, endchr, inpbufpos - (endchr - inpbuf));
+
+				/* and store new length */
+				inpbufpos = inpbufpos - (endchr - inpbuf);
+
+				/* mark begining of stream as last checked */
+				lastcheck = inpbuf;
+
+				/* and try to process another line */
+				continue;
+			} else if (inpbufpos == sizeof inpbuf) {
+				/* we overflowed the buffer */
+				/* XXX - best way is to throw away this line */
+				inpbufpos = 0;
+			}
+		} while (0);
+
+		/* if we copied all the data */
+		if (cpylen == CDC_RX_LEN) {
+			/* declare that we are ready to receive more data */
+			CDC_RX_LEN = 0;
+			USBD_CDC_ReceivePacket(&hUsbDeviceFS);
+		} else {
+			/* if not, move the remaining to the begining and try again */
+			memmove(CDC_RX_BUFFER, &CDC_RX_BUFFER[cpylen], CDC_RX_LEN - cpylen);
+			CDC_RX_LEN -= cpylen;
+		}
+	}
 	goto loop;
 }