// zlox_initrd.h -- Defines the interface and structures relating to the initial ramdisk.

#ifndef _ZLOX_INITRD_H_
#define _ZLOX_INITRD_H_

#include "zlox_common.h"
#include "zlox_fs.h"

typedef struct _ZLOX_INITRD_HEADER
{
	ZLOX_UINT32 nfiles; // The number of files in the ramdisk.
}  ZLOX_INITRD_HEADER;

typedef struct _ZLOX_INITRD_FILE_HEADER
{
	ZLOX_UINT8 magic; // Magic number, for error checking.
	ZLOX_CHAR name[64]; // Filename.
	ZLOX_UINT32 offset; // Offset in the initrd that the file starts.
	ZLOX_UINT32 length; // Length of the file.
} ZLOX_INITRD_FILE_HEADER;

ZLOX_FS_NODE * zlox_initialise_initrd(ZLOX_UINT32 location);

#endif //_ZLOX_INITRD_H_

// zlox_fs.c -- Defines the interface and structures relating to the virtual file system.

#include "zlox_fs.h"

ZLOX_FS_NODE *fs_root = 0; // The root of the filesystem.

ZLOX_UINT32 zlox_read_fs(ZLOX_FS_NODE *node, ZLOX_UINT32 offset, ZLOX_UINT32 size, ZLOX_UINT8 *buffer)
{
    // Has the node got a read callback?
    if (node->read != 0)
        return node->read(node, offset, size, buffer);
    else
        return 0;
}

ZLOX_DIRENT * zlox_readdir_fs(ZLOX_FS_NODE *node, ZLOX_UINT32 index)
{
    // Is the node a directory, and does it have a callback?
    if ( (node->flags & 0x7) == ZLOX_FS_DIRECTORY &&
         node->readdir != 0 )
        return node->readdir(node, index);
    else
        return 0;
}

ZLOX_FS_NODE * zlox_finddir_fs(ZLOX_FS_NODE *node, ZLOX_CHAR *name)
{
    // Is the node a directory, and does it have a callback?
    if ( (node->flags & 0x7) == ZLOX_FS_DIRECTORY &&
         node->finddir != 0 )
        return node->finddir(node, name);
    else
        return 0;
}

/* zlox_multiboot.h -- Declares the multiboot info structure.*/

#ifndef _ZLOX_MULTIBOOT_H_
#define _ZLOX_MULTIBOOT_H_

struct _ZLOX_MULTIBOOT
{
	ZLOX_UINT32 flags;
	ZLOX_UINT32 mem_lower;
	ZLOX_UINT32 mem_upper;
	ZLOX_UINT32 boot_device;
	ZLOX_UINT32 cmdline;
	ZLOX_UINT32 mods_count;
	ZLOX_UINT32 mods_addr;
	ZLOX_UINT32 num;
	ZLOX_UINT32 size;
	ZLOX_UINT32 addr;
	ZLOX_UINT32 shndx;
	ZLOX_UINT32 mmap_length;
	ZLOX_UINT32 mmap_addr;
	ZLOX_UINT32 drives_length;
	ZLOX_UINT32 drives_addr;
	ZLOX_UINT32 config_table;
	ZLOX_UINT32 boot_loader_name;
	ZLOX_UINT32 apm_table;
	ZLOX_UINT32 vbe_control_info;
	ZLOX_UINT32 vbe_mode_info;
	ZLOX_UINT32 vbe_mode;
	ZLOX_UINT32 vbe_interface_seg;
	ZLOX_UINT32 vbe_interface_off;
	ZLOX_UINT32 vbe_interface_len;
}  __attribute__((packed));

typedef struct _ZLOX_MULTIBOOT ZLOX_MULTIBOOT;

#endif //_ZLOX_MULTIBOOT_H_

	+-------------------+
0	| flags		    |	(required)
	+-------------------+
4	| mem_lower	    |	(present if flags[0] is set)
8	| mem_upper	    |	(present if flags[0] is set)
	+-------------------+
12	| boot_device	    |	(present if flags[1] is set)
	+-------------------+
16	| cmdline	    |	(present if flags[2] is set)
	+-------------------+
20	| mods_count	    |	(present if flags[3] is set)
24	| mods_addr	    |	(present if flags[3] is set)
	+-------------------+
28 - 40 | syms		    |   (present if flags[4] or flags[5] is set)
	+-------------------+
44	| mmap_length	    |	(present if flags[6] is set)
48	| mmap_addr	    |	(present if flags[6] is set)
	+-------------------+

	+-------------------+
0	| mod_start	    |
4	| mod_end	    |
	+-------------------+
8	| string	    |
	+-------------------+
12	| reserved (0)	    |
	+-------------------+

ZLOX_FS_NODE * zlox_initialise_initrd(ZLOX_UINT32 location)
{
	// Initialise the main and file header pointers and populate the root directory.
	initrd_header = (ZLOX_INITRD_HEADER *)location;
	file_headers = (ZLOX_INITRD_FILE_HEADER *) (location+sizeof(ZLOX_INITRD_HEADER));

	// Initialise the root directory.
	initrd_root = (ZLOX_FS_NODE *)zlox_kmalloc(sizeof(ZLOX_FS_NODE));
	zlox_strcpy(initrd_root->name, "initrd");
	initrd_root->mask = initrd_root->uid = initrd_root->gid = initrd_root->inode = initrd_root->length = 0;
	initrd_root->flags = ZLOX_FS_DIRECTORY;
	initrd_root->read = 0;
	initrd_root->write = 0;
	initrd_root->open = 0;
	initrd_root->close = 0;
	initrd_root->readdir = &zlox_initrd_readdir;
	initrd_root->finddir = &zlox_initrd_finddir;
	initrd_root->ptr = 0;
	initrd_root->impl = 0;

	// Initialise the /dev directory (required!)
	initrd_dev = (ZLOX_FS_NODE *)zlox_kmalloc(sizeof(ZLOX_FS_NODE));
	zlox_strcpy(initrd_dev->name, "dev");
	initrd_dev->mask = initrd_dev->uid = initrd_dev->gid = initrd_dev->inode = initrd_dev->length = 0;
	initrd_dev->flags = ZLOX_FS_DIRECTORY;
	initrd_dev->read = 0;
	initrd_dev->write = 0;
	initrd_dev->open = 0;
	initrd_dev->close = 0;
	initrd_dev->readdir = &zlox_initrd_readdir;
	initrd_dev->finddir = &zlox_initrd_finddir;
	initrd_dev->ptr = 0;
	initrd_dev->impl = 0;

	root_nodes = (ZLOX_FS_NODE *)zlox_kmalloc(sizeof(ZLOX_FS_NODE) * initrd_header->nfiles);
	nroot_nodes = initrd_header->nfiles;

	// For every file...
	ZLOX_UINT32 i;
	for (i = 0; i < initrd_header->nfiles; i++)
	{
		// Edit the file's header - currently it holds the file offset
		// relative to the start of the ramdisk. We want it relative to the start
		// of memory.
		file_headers[i].offset += location;
		// Create a new file node.
		zlox_strcpy(root_nodes[i].name, (const ZLOX_CHAR *)file_headers[i].name);
		root_nodes[i].mask = root_nodes[i].uid = root_nodes[i].gid = 0;
		root_nodes[i].length = file_headers[i].length;
		root_nodes[i].inode = i;
		root_nodes[i].flags = ZLOX_FS_FILE;
		root_nodes[i].read = &zlox_initrd_read;
		root_nodes[i].write = 0;
		root_nodes[i].readdir = 0;
		root_nodes[i].finddir = 0;
		root_nodes[i].open = 0;
		root_nodes[i].close = 0;
		root_nodes[i].impl = 0;
	}
	return initrd_root;
}

//zenglOX kernel main entry
ZLOX_SINT32 zlox_kernel_main(ZLOX_MULTIBOOT * mboot_ptr)
{

..............................
..............................

	// Initialise the initial ramdisk, and set it as the filesystem root.
	fs_root = zlox_initialise_initrd(initrd_location);

	// list the contents of /
	ZLOX_SINT32 i = 0;
	ZLOX_DIRENT *node = 0;
	while ( (node = zlox_readdir_fs(fs_root, i)) != 0)
	{
		zlox_monitor_write("Found file ");
		zlox_monitor_write(node->name);
		ZLOX_FS_NODE *fsnode = zlox_finddir_fs(fs_root, node->name);

		if ((fsnode->flags&0x7) == ZLOX_FS_DIRECTORY)
		{
			zlox_monitor_write("\n\t(directory)\n");
		}
		else
		{
			zlox_monitor_write("\n\t contents: \"");
			ZLOX_CHAR buf[256];
			ZLOX_UINT32 sz = zlox_read_fs(fsnode, 0, 256, (ZLOX_UINT8 *)buf);
			ZLOX_UINT32 j;
			for (j = 0; j < sz; j++)
				zlox_monitor_put(buf[j]);
			
			zlox_monitor_write("\"\n");
		}
		i++;
	}

	// Write out a sample string
	zlox_monitor_write("hello world!\nwelcome to zenglOX v0.0.7!\n");

..............................
..............................

}