// 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 "x86.h"
#include "traps.h"
#include "spinlock.h"
#include "sleeplock.h"
#include "fs.h"
#include "buf.h"

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 / BSIZE;
}

// 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 (!holdingsleep(&b->lock)) {
        panic("iderw: buf not locked");
    }
    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->blockno >= disksize) {
        panic("iderw: block out of range");
    }

    p = memdisk + b->blockno * BSIZE;

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