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pci: add helper functions to check ranges overlap. 

add helper function to check ranges overlap suggested by
Michael S. Tsirkin <mst@redhat.com>.
His original suggestion was to use [first, last], however I chosen
to use offset, length pair, i.e. [offset, offset + length)
because pci configuration space related functions all uses offset and length
pair, so it helps to avoid to type constant twice.

Cc: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Isaku Yamahata <yamahata@valinux.co.jp>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
This commit is contained in:
Isaku Yamahata 2009-10-30 21:21:19 +09:00 committed by Anthony Liguori
parent a9f4994611
commit f49db805a9
1 changed files with 29 additions and 0 deletions
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29
hw/pci.h
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@ -406,4 +406,33 @@ PCIBus *pci_apb_init(target_phys_addr_t special_base,
PCIBus *sh_pci_register_bus(pci_set_irq_fn set_irq, pci_map_irq_fn map_irq,
void *pic, int devfn_min, int nirq);
/* These are not pci specific. Should move into a separate header.
* Only pci.c uses them, so keep them here for now.
*/
/* Get last byte of a range from offset + length.
* Undefined for ranges that wrap around 0. */
static inline uint64_t range_get_last(uint64_t offset, uint64_t len)
{
return offset + len - 1;
}
/* Check whether a given range covers a given byte. */
static inline int range_covers_byte(uint64_t offset, uint64_t len,
uint64_t byte)
{
return offset <= byte && byte <= range_get_last(offset, len);
}
/* Check whether 2 given ranges overlap.
* Undefined if ranges that wrap around 0. */
static inline int ranges_overlap(uint64_t first1, uint64_t len1,
uint64_t first2, uint64_t len2)
{
uint64_t last1 = range_get_last(first1, len1);
uint64_t last2 = range_get_last(first2, len2);
return !(last2 < first1 || last1 < first2);
}
#endif