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I/O vector helpers (Avi Kivity)

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In general, it is not possible to predict the size of of an I/O vector since
a contiguous guest region may map to a disconiguous host region.  Add some
helpers to manage I/O vector growth.

Signed-off-by: Avi Kivity <avi@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>


git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@6396 c046a42c-6fe2-441c-8c8c-71466251a162
This commit is contained in:
aliguori 2009-01-22 16:59:20 +00:00
parent ba223c29da
commit 44e3ee8a2a
2 changed files with 59 additions and 0 deletions
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47
cutils.c
View File

@ -101,3 +101,50 @@ int qemu_fls(int i)
{
return 32 - clz32(i);
}
/* io vectors */
void qemu_iovec_init(QEMUIOVector *qiov, int alloc_hint)
{
qiov->iov = qemu_malloc(alloc_hint * sizeof(struct iovec));
qiov->niov = 0;
qiov->nalloc = alloc_hint;
}
void qemu_iovec_add(QEMUIOVector *qiov, void *base, size_t len)
{
if (qiov->niov == qiov->nalloc) {
qiov->nalloc = 2 * qiov->nalloc + 1;
qiov->iov = qemu_realloc(qiov->iov, qiov->nalloc * sizeof(struct iovec));
}
qiov->iov[qiov->niov].iov_base = base;
qiov->iov[qiov->niov].iov_len = len;
++qiov->niov;
}
void qemu_iovec_destroy(QEMUIOVector *qiov)
{
qemu_free(qiov->iov);
}
void qemu_iovec_to_buffer(QEMUIOVector *qiov, void *buf)
{
uint8_t *p = (uint8_t *)buf;
int i;
for (i = 0; i < qiov->niov; ++i) {
memcpy(p, qiov->iov[i].iov_base, qiov->iov[i].iov_len);
p += qiov->iov[i].iov_len;
}
}
void qemu_iovec_from_buffer(QEMUIOVector *qiov, const void *buf)
{
const uint8_t *p = (const uint8_t *)buf;
int i;
for (i = 0; i < qiov->niov; ++i) {
memcpy(qiov->iov[i].iov_base, p, qiov->iov[i].iov_len);
p += qiov->iov[i].iov_len;
}
}

12
qemu-common.h
View File

@ -191,6 +191,18 @@ int cpu_load(QEMUFile *f, void *opaque, int version_id);
/* Force QEMU to stop what it's doing and service IO */
void qemu_service_io(void);
typedef struct QEMUIOVector {
struct iovec *iov;
int niov;
int nalloc;
} QEMUIOVector;
void qemu_iovec_init(QEMUIOVector *qiov, int alloc_hint);
void qemu_iovec_add(QEMUIOVector *qiov, void *base, size_t len);
void qemu_iovec_destroy(QEMUIOVector *qiov);
void qemu_iovec_to_buffer(QEMUIOVector *qiov, void *buf);
void qemu_iovec_from_buffer(QEMUIOVector *qiov, const void *buf);
#endif /* dyngen-exec.h hack */
#endif