# HG changeset patch
# User Mychaela Falconia <falcon@freecalypso.org>
# Date 1730097282 0
# Node ID e93a11f44e6f9d5a29272d66161a72cb3ddab675
# Parent  c1d9b5d128f5b34117ed65d16691f2308c97bd47
fc-mcsi-rxtx: implement basic Tx

diff -r c1d9b5d128f5 -r e93a11f44e6f sw/mcsi-rxtx/Makefile
--- a/sw/mcsi-rxtx/Makefile	Mon Oct 28 06:11:23 2024 +0000
+++ b/sw/mcsi-rxtx/Makefile	Mon Oct 28 06:34:42 2024 +0000
@@ -1,7 +1,7 @@
 CC=	gcc
 CFLAGS=	-O2
 PROG=	fc-mcsi-rxtx
-OBJS=	main.o mainloop.o rx_samples.o ttymagic.o usercmd.o
+OBJS=	main.o mainloop.o rx_samples.o ttymagic.o tx_func.o usercmd.o
 LIBS=	../libserial/libserial.a
 
 INSTALL_PREFIX=	/opt/freecalypso
diff -r c1d9b5d128f5 -r e93a11f44e6f sw/mcsi-rxtx/mainloop.c
--- a/sw/mcsi-rxtx/mainloop.c	Mon Oct 28 06:11:23 2024 +0000
+++ b/sw/mcsi-rxtx/mainloop.c	Mon Oct 28 06:34:42 2024 +0000
@@ -71,6 +71,7 @@
 			if (off >= sizeof(buf)) {
 				process_rx_block(buf);
 				off = 0;
+				transmit_20ms_block();
 			}
 		}
 		fflush(stdout);
diff -r c1d9b5d128f5 -r e93a11f44e6f sw/mcsi-rxtx/tx_func.c
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/sw/mcsi-rxtx/tx_func.c	Mon Oct 28 06:34:42 2024 +0000
@@ -0,0 +1,48 @@
+/*
+ * Here we implement basic Tx functions: emitting an uplink sample stream
+ * to Calypso MCSI via the FPGA.
+ */
+
+#include <sys/types.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+
+extern int target_fd;
+
+u_short pcm_fill_word;
+
+static void
+do_idle_fill(buf)
+	u_short *buf;
+{
+	unsigned n;
+
+	for (n = 0; n < 160; n++)
+		buf[n] = pcm_fill_word;
+}
+
+static void
+emit_uart_output(samples)
+	u_short *samples;
+{
+	u_char bytes[320], *dp;
+	unsigned n, samp;
+
+	dp = bytes;
+	for (n = 0; n < 160; n++) {
+		samp = samples[n];
+		*dp++ = samp;
+		*dp++ = samp >> 8;
+	}
+	write(target_fd, bytes, 320);
+}
+
+void
+transmit_20ms_block()
+{
+	u_short tx_samples[160];
+
+	do_idle_fill(tx_samples);
+	emit_uart_output(tx_samples);
+}