From befee0cf6bd5388a7102d6689e6af6eae0fe5649 Mon Sep 17 00:00:00 2001
From: Ali Mashtizadeh <mashti@cs.stanford.edu>
Date: Sun, 13 Jul 2014 14:22:59 -0700
Subject: [PATCH] Debug console working over serial

---
 include/string.h      |  1 +
 sys/dev/console.c     | 11 +++++++--
 sys/dev/x86/vgacons.c |  6 +++++
 sys/kern/debug.c      | 52 ++++++++++++++++++++++++++++++++++++++++---
 4 files changed, 65 insertions(+), 5 deletions(-)

diff --git a/include/string.h b/include/string.h
index b42fa4c..40d2175 100644
--- a/include/string.h
+++ b/include/string.h
@@ -7,6 +7,7 @@
 void *memcpy(void *dst, const void *src, size_t len);
 void *memset(void *dst, int c, size_t len);
 
+char *strchr(const char *s, int c);
 int strcmp(const char *s1, const char *s2);
 char *strcpy(char *to, const char *from);
 size_t strlen(const char *str);
diff --git a/sys/dev/console.c b/sys/dev/console.c
index 6b82e23..060d267 100644
--- a/sys/dev/console.c
+++ b/sys/dev/console.c
@@ -43,8 +43,15 @@ Console_Gets(char *str, size_t n)
     for (i = 0; i < (n - 1); i++)
     {
 	char ch = Console_Getc();
-	if (ch == '\r')
-	{
+	if (ch == '\b') {
+	    if (i > 0) {
+		Console_Putc(ch);
+		i--;
+	    }
+	    i--;
+	    continue;
+	}
+	if (ch == '\r') {
 	    Console_Putc('\n');
 	    str[i] = '\0';
 	    return;
diff --git a/sys/dev/x86/vgacons.c b/sys/dev/x86/vgacons.c
index 4470824..eebeb19 100644
--- a/sys/dev/x86/vgacons.c
+++ b/sys/dev/x86/vgacons.c
@@ -110,6 +110,12 @@ void VGA_Putc(short c)
     c |= (TextAttribute << 8);
     switch (c & 0xFF)
     {
+        case '\b':
+	    if (CurrentX > 0) {
+		CurrentX--;
+		VideoBuffer[CurrentX + CurrentY * SizeX] = 0x20 | (TextAttribute << 8);
+	    }
+	    break;
         case '\n':
             if (CurrentY >= (SizeY - 1)) {
                 VGA_ScrollDisplay();
diff --git a/sys/kern/debug.c b/sys/kern/debug.c
index 9832754..460a9be 100644
--- a/sys/kern/debug.c
+++ b/sys/kern/debug.c
@@ -16,12 +16,16 @@
 
 #include <stdbool.h>
 #include <stdint.h>
+#include <string.h>
 
 #include <kassert.h>
 #include <kdebug.h>
 
 #include "../dev/console.h"
 
+#define DEBUG_MAX_LINE		128
+#define DEBUG_MAX_ARGS		16
+
 void
 Debug_PrintHex(const char *data, size_t length, off_t off, size_t limit)
 {
@@ -73,16 +77,38 @@ Debug_PrintHex(const char *data, size_t length, off_t off, size_t limit)
     }
 }
 
+#define PHELP(_cmd, _msg) kprintf("%-16s %s\n", _cmd, _msg)
+
+void
+Debug_Help(int argc, const char *argv[])
+{
+    PHELP("dump", "Dump a region of memory");
+    PHELP("help", "Display the list of commands");
+}
+
+void
+Debug_Echo(int argc, const char *argv[])
+{
+    int i;
+
+    for (i = 1; i < argc; i++)
+    {
+	kprintf("%s ", argv[i]);
+    }
+    kprintf("\n");
+}
+
 void
 Debug_Dump(int argc, const char *argv[])
 {
 }
 
-#define DEBUG_MAX_LINE		128
-
 void
 Debug_Prompt()
 {
+    int argc;
+    char *argv[DEBUG_MAX_ARGS];
+    char *nextArg;
     char buf[DEBUG_MAX_LINE];
     kprintf("Entered Debugger!\n");
 
@@ -90,11 +116,31 @@ Debug_Prompt()
 	kprintf("> ");
 
 	// read input
-	Console_Gets(&buf, DEBUG_MAX_LINE);
+	Console_Gets((char *)&buf, DEBUG_MAX_LINE);
 
 	// parse input
+	argv[0] = buf;
+	for (argc = 1; argc < DEBUG_MAX_ARGS; argc++) {
+	    nextArg = strchr(argv[argc - 1], ' ');
+	    if (nextArg == NULL)
+	    {
+		break;
+	    }
+
+	    *nextArg = '\0';
+	    argv[argc] = nextArg + 1;
+	}
 
 	// execute command
+	if (strcmp(argv[0], "help") == 0) {
+	    Debug_Help(argc, argv);
+	} else if (strcmp(argv[0], "dump") == 0) {
+	    Debug_Dump(argc, argv);
+	} else if (strcmp(argv[0], "echo") == 0) {
+	    Debug_Echo(argc, argv);
+	} else if (strcmp(argv[0], "") != 0) {
+	    kprintf("Unknown command '%s'\n", argv[0]);
+	}
     }
 }