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comparison src/memide.c @ 0:83c23a36980d

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Init
author Tatsuki IHA <e125716@ie.u-ryukyu.ac.jp>
date Fri, 26 May 2017 23:11:05 +0900
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-1:000000000000 0:83c23a36980d
1 // Fake IDE disk; stores blocks in memory.
2 // Useful for running kernel without scratch disk.
3
4 #include "types.h"
5 #include "defs.h"
6 #include "param.h"
7 #include "mmu.h"
8 #include "proc.h"
9 #include "spinlock.h"
10 #include "buf.h"
11
12 // a file system image, embeded
13 extern uchar _binary_fs_img_start[], _binary_fs_img_size[];
14
15 static int disksize;
16 static uchar *memdisk;
17
18 void ideinit(void)
19 {
20 memdisk = _binary_fs_img_start;
21 disksize = (uint)_binary_fs_img_size/512;
22 }
23
24 // Interrupt handler.
25 void ideintr(void)
26 {
27 // no-op
28 }
29
30 // Sync buf with disk.
31 // If B_DIRTY is set, write buf to disk, clear B_DIRTY, set B_VALID.
32 // Else if B_VALID is not set, read buf from disk, set B_VALID.
33 void iderw(struct buf *b)
34 {
35 uchar *p;
36
37 if(!(b->flags & B_BUSY)) {
38 panic("iderw: buf not busy");
39 }
40
41 if((b->flags & (B_VALID|B_DIRTY)) == B_VALID) {
42 panic("iderw: nothing to do");
43 }
44
45 if(b->dev != 1) {
46 panic("iderw: request not for disk 1");
47 }
48
49 if(b->sector >= disksize) {
50 panic("iderw: sector out of range");
51 }
52
53 p = memdisk + b->sector*512;
54
55 if(b->flags & B_DIRTY){
56 b->flags &= ~B_DIRTY;
57 memmove(p, b->data, 512);
58 } else {
59 memmove(b->data, p, 512);
60 }
61
62 b->flags |= B_VALID;
63 }