// Simple command-line kernel monitor useful for
// controlling the kernel and exploring the system interactively.

#include <inc/stdio.h>
#include <inc/string.h>
#include <inc/memlayout.h>
#include <inc/assert.h>
#include <inc/x86.h>

#include <kern/console.h>
#include <kern/monitor.h>
#include <kern/trap.h>
#include <kern/kdebug.h>

#define CMDBUF_SIZE	80	// enough for one VGA text line


struct Command {
	const char *name;
	const char *desc;
	// return -1 to force monitor to exit
	int (*func)(int argc, char** argv, struct Trapframe* tf);
};

static struct Command commands[] = {
	{ "help", "Display this list of commands", mon_help },
	{ "kerninfo", "Display information about the kernel", mon_kerninfo },
	{"backtrace" , "Display the back trace" , mon_backtrace},
};
#define NCOMMANDS (sizeof(commands)/sizeof(commands[0]))

unsigned read_eip();

/***** Implementations of basic kernel monitor commands *****/

int
mon_help(int argc, char **argv, struct Trapframe *tf)
{
	int i;

	for (i = 0; i < NCOMMANDS; i++)
		cprintf("%s - %s\n", commands[i].name, commands[i].desc);
	return 0;
}

int
mon_kerninfo(int argc, char **argv, struct Trapframe *tf)
{
	extern char _start[], etext[], edata[], end[];

	cprintf("Special kernel symbols:\n");
	cprintf("  _start %08x (virt)  %08x (phys)\n", _start, _start - KERNBASE);
	cprintf("  etext  %08x (virt)  %08x (phys)\n", etext, etext - KERNBASE);
	cprintf("  edata  %08x (virt)  %08x (phys)\n", edata, edata - KERNBASE);
	cprintf("  end    %08x (virt)  %08x (phys)\n", end, end - KERNBASE);
	cprintf("Kernel executable memory footprint: %dKB\n",
		(end-_start+1023)/1024);
	return 0;
}



int
mon_backtrace(int argc, char **argv, struct Trapframe *tf)
{
	uint32_t ebp = read_ebp();

	//need to recurse
	while (ebp != 0) {
		int eip = *((uint32_t *)(ebp+4));
		struct Eipdebuginfo info;
		debuginfo_eip(eip, &info);
		cprintf("%s%x%s%x\n",info.eip_file, info.eip_line,info.eip_fn_name, eip - info.eip_fn_addr);
		cprintf("ebp %x ",ebp);
		cprintf("eip %x ",eip);
		cprintf("args %08x %08x %08x %08x %08x \n", *(uint32_t *)(ebp+8), *(uint32_t *)(ebp+12), *(uint32_t *)(ebp+16), *(uint32_t *)(ebp+20), *(uint32_t *)(ebp+24));

		ebp = *(uint32_t *) ebp;
	}

	return 0;
}



/***** Kernel monitor command interpreter *****/

#define WHITESPACE "\t\r\n "
#define MAXARGS 16

static int
runcmd(char *buf, struct Trapframe *tf)
{
	int argc;
	char *argv[MAXARGS];
	int i;

	// Parse the command buffer into whitespace-separated arguments
	argc = 0;
	argv[argc] = 0;
	while (1) {
		// gobble whitespace
		while (*buf && strchr(WHITESPACE, *buf))
			*buf++ = 0;
		if (*buf == 0)
			break;

		// save and scan past next arg
		if (argc == MAXARGS-1) {
			cprintf("Too many arguments (max %d)\n", MAXARGS);
			return 0;
		}
		argv[argc++] = buf;
		while (*buf && !strchr(WHITESPACE, *buf))
			buf++;
	}
	argv[argc] = 0;

	// Lookup and invoke the command
	if (argc == 0)
		return 0;
	for (i = 0; i < NCOMMANDS; i++) {
		if (strcmp(argv[0], commands[i].name) == 0)
			return commands[i].func(argc, argv, tf);
	}
	cprintf("Unknown command '%s'\n", argv[0]);
	return 0;
}

/*
 A return value of:
	-> 0 means continue
	-> -1 means destroy env
*/
int 
better_monitor(struct Trapframe *tf)
{
	char *buf;

	cprintf("Welcome to the JOS kernel monitor!\n");
	cprintf("Type 'help' for a list of commands.\n");

	if (tf != NULL)
		print_trapframe(tf);

	while (1) {
		buf = readline("K> ");
		if (buf != NULL) {
			tf->tf_eflags &= 0xfffffeff;
			if (strcmp(buf, "continue") == 0) {				
				return 0;
			}
			if (strcmp(buf,"step") == 0) {
				tf->tf_eflags |= (1 << 8);
				return 0;
			}
			if (runcmd(buf, tf) < 0)
				break;
		}
	}
	return -1;
}


void
monitor(struct Trapframe *tf)
{
	char *buf;

	cprintf("Welcome to the JOS kernel monitor!\n");
	cprintf("Type 'help' for a list of commands.\n");

	if (tf != NULL)
		print_trapframe(tf);

	while (1) {
		buf = readline("K> ");
		if (buf != NULL) {
			if (runcmd(buf, tf) < 0)
				break;
		}
	}
}

// return EIP of caller.
// does not work if inlined.
// putting at the end of the file seems to prevent inlining.
unsigned
read_eip()
{
	uint32_t callerpc;
	__asm __volatile("movl 4(%%ebp), %0" : "=r" (callerpc));
	return callerpc;
}