Initial Upload

memide.c

@@ -0,0 +1,60 @@
+// 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;
+}