From 7282e8f84e4f5aecab6e57c2086785bbd6d48748 Mon Sep 17 00:00:00 2001
From: Joshua Wise <joshua@rebirth.joshuawise.com>
Date: Sat, 24 Jan 2009 00:40:32 -0500
Subject: [PATCH] Terminal: Add support for reading characters.

---
 Terminal.v    | 11 +++++++++++
 testbench.cpp | 47 ++++++++++++++++++++++++++++++++++++-----------
 2 files changed, 47 insertions(+), 11 deletions(-)

diff --git a/Terminal.v b/Terminal.v
index 89b19d5..dd041d0 100644
--- a/Terminal.v
+++ b/Terminal.v
@@ -12,6 +12,8 @@ module Terminal(
 	/* Terminal pretends to be cp5. */
 	reg towrite = 0;
 	reg [7:0] data = 0;
+	reg [8:0] indata = 0;	/* High bit is if data is present. */
+	reg didread = 0;
 	
 	always @(*)
 	begin
@@ -19,16 +21,25 @@ module Terminal(
 		data = 8'hxx;
 		cp_ack = 0;
 		cp_busy = 0;
+		cp_read = 0;
+		didread = 0;
 		if (cp_req && (cp_rnw == 0) && (cp_insn[27:24] == 4'b1110) && (cp_insn[19:16] == 4'b0000) && (cp_insn[11:8] == 4'h5))
 		begin
 			towrite = 1;
 			data = cp_write[7:0];
 			cp_ack = 1;
+		end else if (cp_req && (cp_rnw == 1) && (cp_insn[27:24] == 4'b1110) && (cp_insn[19:16] == 4'b0001) && (cp_insn[11:8] == 4'h5))
+		begin
+			cp_read = {23'h0, indata[8:0]};
+			cp_ack = 1;
+			didread = cp_insn[7:5] == 1;
 		end
 	end
 `ifdef verilator	
 	always @(posedge clk)
 		if (towrite)
 			$c("{extern void term_output(unsigned char d); term_output(",data,");}");
+		else if (didread || !indata[8])
+			indata = $c("({extern unsigned int term_input(); term_input();})");
 `endif
 endmodule
diff --git a/testbench.cpp b/testbench.cpp
index 53be841..e89de38 100644
--- a/testbench.cpp
+++ b/testbench.cpp
@@ -3,26 +3,51 @@
 #define _XOPEN_SOURCE
 #include <stdlib.h>
 #include <fcntl.h>
+#include <termios.h>
 
 Vsystem *top;
 
+int ptyfd = -1;
+
+void openpty()
+{
+	int fd = posix_openpt(O_RDWR);
+	char b[128];
+	struct termios kbdios;
+	
+	grantpt(fd);  
+	fcntl(fd, F_SETFD, 0);	/* clear close-on-exec */
+	tcgetattr(fd, &kbdios);
+	kbdios.c_lflag &= ~(ECHO|ECHONL|ICANON|ISIG|IEXTEN);
+	tcsetattr(fd, TCSANOW, &kbdios);
+	sprintf(b, "rxvt -pty-fd %d -bg black -fg white -title \"Output terminal\" &", fd);
+	system(b);
+	unlockpt(fd);
+	ptyfd = open(ptsname(fd), O_RDWR | O_NONBLOCK);
+	close(fd);
+}
+
+unsigned int term_input()
+{
+	int rv;
+	unsigned char c;
+	if (ptyfd == -1)
+		openpty();
+	rv = read(ptyfd, &c, 1);
+	if (rv < 0)
+		return 0;
+	return 0x100 | c;
+}
+
 void term_output(unsigned char d)
 {
 	int fd = posix_openpt(O_RDWR);
 	static int fd2 = -1;
 	char b[128];
 
-	if (fd2 == -1)
-	{
-		grantpt(fd);  
-		fcntl(fd, F_SETFD, 0);	/* clear close-on-exec */
-		sprintf(b, "rxvt -pty-fd %d -bg black -fg white -title \"Output terminal\" &", fd);
-		system(b);
-		unlockpt(fd);
-		fd2 = open(ptsname(fd), O_RDWR);
-		close(fd);
-	}
-	write(fd2, &d, 1);
+	if (ptyfd == -1)
+		openpty();
+	write(ptyfd, &d, 1);
 }
 
 unsigned int main_time = 0;
-- 
2.39.2