bcopy(D3) bcopy(D3)
NAME
bcopy - copy data between address locations in the kernel
SYNOPSIS
#include <sys/types.h>
#include <sys/ddi.h>
void bcopy(caddr_t from, caddr_t to, size_t bcount);
Arguments
from Source address from which the copy is made.
to Destination address to which the copy is made.
bcount Number of bytes to be copied.
DESCRIPTION
bcopy copies bcount bytes from one kernel address to another.
It chooses the best algorithm based on address alignment and
number of bytes to copy.
Return Values
None
USAGE
If the input and output addresses overlap, the function
executes, but the results are undefined.
The source and destination address ranges must both be within
the kernel address space and must be memory resident. No
range checking is done. Since there is no mechanism by which
drivers that conform to the rules of the DDI/DKI can obtain
and use a kernel address which is not memory resident (an
address which is paged out), DDI/DKI conforming drivers can
assume that any address to which they have access is memory
resident and therefore a valid argument to bcopy. Addresses
within user address space are not valid arguments, and
specifying such an address may cause the driver to corrupt the
system in an unpredictable way. For copying between kernel
and user space, drivers must use an appropriate function
defined for that purpose (for example, copyin(D3),
copyout(D3), uiomove(D3), ureadc(D3), or uwritec(D3)).
Level
Initialization, Base or Interrupt.
Copyright 1994 Novell, Inc. Page 1
bcopy(D3) bcopy(D3)
Synchronization Constraints
Does not sleep.
Driver-defined basic locks, read/write locks, and sleep locks
may be held across calls to this function.
Examples
An I/O request is made for data stored in a RAM disk. If the
I/O operation is a read request, data are copied from the RAM
disk to a buffer (line 9). If it is a write request, data are
copied from a buffer to the RAM disk (line 15). The bcopy
function is used since both the RAM disk and the buffer are
part of the kernel address space.
1 #define RAMDNBLK 1000 /* number of blocks in the RAM disk */
2 #define RAMDBSIZ NBPSCTR /* bytes per block */
3 char ramdblks[RAMDNBLK][RAMDBSIZ]; /* blocks forming RAM disk */
...
4
5 if (bp->b_flags & B_READ) {
6 /*
7 * read request - copy data from RAM disk to system buffer
8 */
9 bcopy(ramdblks[bp->b_blkno], bp->b_un.b_addr, bp->b_bcount);
10
11 } else {
12 /*
13 * write request - copy data from system buffer to RAM disk
14 */
15 bcopy(bp->b_un.b_addr, ramdblks[bp->b_blkno], bp->b_bcount);
16 }
REFERENCES
copyin(D3), copyout(D3), ovbcopy(D3), uiomove(D3), ureadc(D3),
uwritec(D3)
NOTICES
Portability
All processors
Applicability
ddi: 1, 2, 3, 4, 5, 5mp, 6, 6mp, 7, 7mp
Copyright 1994 Novell, Inc. Page 2