xv6-65oo2/kernel/ramdisk.c
2019-06-11 09:57:14 -04:00

46 lines
943 B
C

//
// ramdisk that uses the disk image loaded by qemu -rdinit fs.img
//
#include "types.h"
#include "riscv.h"
#include "defs.h"
#include "param.h"
#include "memlayout.h"
#include "spinlock.h"
#include "sleeplock.h"
#include "fs.h"
#include "buf.h"
void
ramdiskinit(void)
{
}
// 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
ramdiskrw(struct buf *b)
{
if(!holdingsleep(&b->lock))
panic("ramdiskrw: buf not locked");
if((b->flags & (B_VALID|B_DIRTY)) == B_VALID)
panic("ramdiskrw: nothing to do");
if(b->blockno >= FSSIZE)
panic("ramdiskrw: blockno too big");
uint64 diskaddr = b->blockno * BSIZE;
char *addr = (char *)RAMDISK + diskaddr;
if(b->flags & B_DIRTY){
// write
memmove(addr, b->data, BSIZE);
b->flags &= ~B_DIRTY;
} else {
// read
memmove(b->data, addr, BSIZE);
b->flags |= B_VALID;
}
}