[Xcb] [PATCH] c_client.py: Add padding after full_sequence for certain XGE events.

[Keith Packard]

Keith Packard <keithp at keithp.com> writes:

> Kenneth Graunke <kenneth at whitecape.org> writes:
>
>> To correct this, we check if the field following full_sequence has a
>> type whose size is 8 bytes.  If so, we add an additional uint32_t field
>> called "pad_fs" (pad after full_sequence).  This is harmless on 32-bit
>> architectures, and essential for 64-bit architectures to function.
>
> I think you need to check to see if *any* extended (past-32bytes) field
> is 64 bits?
>
> Note that this change will break currently working libraries on 32-bit
> systems.

Ok, I think Ken and I came up with a terrible, but functional,
plan. Simply replace any uint64_t members in events with two uint32_t
members, and place those in correct order so that reading a uint64_t
From the same address will work (retaining binary compatibility with
32-bit apps).

I wrote this by hand, just to check to see if it worked (only tested on
32-bit, I'm afraid):

#include <endian.h>
#if __BYTE_ORDER == __LITTLE_ENDIAN
#define xcb_uint64_t(x) uint32_t x ## _lo, x ## _hi
#else
#define xcb_uint64_t(x) uint32_t x ## _hi, x ## _lo
#endif

#define xcb_uint64(x,f)   (((uint64_t) ((x).f ## _hi) << 32) | ((x).f ## _lo))

#define xcb_uint64_store(x,f,v) do {            \
        uint64_t __tmp__ = (v);                 \
        ((x).f ## _hi) = (__tmp__) >> 32;       \
        ((x).f ## _lo) = (__tmp__);             \
    } while (0)

/**
 * @brief xcb_present_complete_notify_event_t
 **/
typedef struct xcb_present_complete_notify_event_t {
    uint8_t             response_type; /**<  */
    uint8_t             extension; /**<  */
    uint16_t            sequence; /**<  */
    uint32_t            length; /**<  */
    uint16_t            event_type; /**<  */
    uint8_t             kind; /**<  */
    uint8_t             mode; /**<  */
    xcb_present_event_t event; /**<  */
    xcb_window_t        window; /**<  */
    uint32_t            serial; /**<  */
    xcb_uint64_t        (ust); /**<  */
    uint32_t            full_sequence; /**<  */
    xcb_uint64_t        (msc); /**<  */
} xcb_present_complete_notify_event_t;

-- 
keith.packard at intel.com
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