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>
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hw/pci.h
29
hw/pci.h
@ -406,4 +406,33 @@ PCIBus *pci_apb_init(target_phys_addr_t special_base,
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PCIBus *sh_pci_register_bus(pci_set_irq_fn set_irq, pci_map_irq_fn map_irq,
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void *pic, int devfn_min, int nirq);
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/* These are not pci specific. Should move into a separate header.
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* Only pci.c uses them, so keep them here for now.
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*/
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/* Get last byte of a range from offset + length.
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* Undefined for ranges that wrap around 0. */
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static inline uint64_t range_get_last(uint64_t offset, uint64_t len)
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{
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return offset + len - 1;
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}
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/* Check whether a given range covers a given byte. */
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static inline int range_covers_byte(uint64_t offset, uint64_t len,
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uint64_t byte)
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{
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return offset <= byte && byte <= range_get_last(offset, len);
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}
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/* Check whether 2 given ranges overlap.
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* Undefined if ranges that wrap around 0. */
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static inline int ranges_overlap(uint64_t first1, uint64_t len1,
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uint64_t first2, uint64_t len2)
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{
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uint64_t last1 = range_get_last(first1, len1);
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uint64_t last2 = range_get_last(first2, len2);
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return !(last2 < first1 || last1 < first2);
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}
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#endif
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