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