// Fake IDE disk; stores blocks in memory.
// Useful for running kernel without scratch disk.

#include "types.h"
#include "defs.h"
#include "param.h"
#include "mmu.h"
#include "proc.h"
#include "spinlock.h"
#include "buf.h"

// a file system image, embeded
extern uchar _binary_fs_img_start[], _binary_fs_img_size[];

static int disksize;
static uchar *memdisk;

void ideinit(void)
{
    memdisk = _binary_fs_img_start;
    disksize = (uint)_binary_fs_img_size/512;
}

// Interrupt handler.
void ideintr(void)
{
    // no-op
}

// Sync buf with disk.
// If B_DIRTY is set, write buf to disk, clear B_DIRTY, set B_VALID.
// Else if B_VALID is not set, read buf from disk, set B_VALID.
void iderw(struct buf *b)
{
    uchar *p;

    if(!(b->flags & B_BUSY)) {
        panic("iderw: buf not busy");
    }

    if((b->flags & (B_VALID|B_DIRTY)) == B_VALID) {
        panic("iderw: nothing to do");
    }

    if(b->dev != 1) {
        panic("iderw: request not for disk 1");
    }

    if(b->sector >= disksize) {
        panic("iderw: sector out of range");
    }

    p = memdisk + b->sector*512;

    if(b->flags & B_DIRTY){
        b->flags &= ~B_DIRTY;
        memmove(p, b->data, 512);
    } else {
        memmove(b->data, p, 512);
    }

    b->flags |= B_VALID;
}