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dma-helpers: add dma_buf_read and dma_buf_write 

These helpers do a full transfer from an in-memory buffer to target
memory, with support for scatter/gather lists.  It will be used to
store the reply of an emulated command into a QEMUSGList provided by
the adapter.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Paolo Bonzini 2011-07-06 08:02:14 +02:00
parent fead0c2410
commit 8171ee35e2
2 changed files with 34 additions and 0 deletions
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31
dma-helpers.c
View File

@ -204,3 +204,34 @@ BlockDriverAIOCB *dma_bdrv_write(BlockDriverState *bs,
{
return dma_bdrv_io(bs, sg, sector, bdrv_aio_writev, cb, opaque, true);
}
static uint64_t dma_buf_rw(uint8_t *ptr, int32_t len, QEMUSGList *sg, bool to_dev)
{
uint64_t resid;
int sg_cur_index;
resid = sg->size;
sg_cur_index = 0;
len = MIN(len, resid);
while (len > 0) {
ScatterGatherEntry entry = sg->sg[sg_cur_index++];
int32_t xfer = MIN(len, entry.len);
cpu_physical_memory_rw(entry.base, ptr, xfer, !to_dev);
ptr += xfer;
len -= xfer;
resid -= xfer;
}
return resid;
}
uint64_t dma_buf_read(uint8_t *ptr, int32_t len, QEMUSGList *sg)
{
return dma_buf_rw(ptr, len, sg, 0);
}
uint64_t dma_buf_write(uint8_t *ptr, int32_t len, QEMUSGList *sg)
{
return dma_buf_rw(ptr, len, sg, 1);
}

3
dma.h
View File

@ -58,4 +58,7 @@ BlockDriverAIOCB *dma_bdrv_read(BlockDriverState *bs,
BlockDriverAIOCB *dma_bdrv_write(BlockDriverState *bs,
QEMUSGList *sg, uint64_t sector,
BlockDriverCompletionFunc *cb, void *opaque);
uint64_t dma_buf_read(uint8_t *ptr, int32_t len, QEMUSGList *sg);
uint64_t dma_buf_write(uint8_t *ptr, int32_t len, QEMUSGList *sg);
#endif