[PATCH] os-windows: fix cpumask operations

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Fix cpumask manipulation on (64-bit) Windows systems.

cpus_allowed=nn values greater than 32 does not work, due
to the compiler not promoting expressions like "1 << cpu" to
64 bits, the clear function clearing the wrong bit (using "cpu - 1"),
and the clear function using XOR to clear (which only works if the
bit was previously set).

Example problems (from extra debug prints):
* setting CPU 32 really sets bit 1 (CPU 0)
	Set mask of 0000000000000000 to add 0000000000000001 (32)

* setting CPU 63 really sets bit 31 (CPU 32)
	Set mask of 0000000000000000 to add 0000000080000000 (63)

* clearing CPU 0 really clears bit 63 (CPU 64)
	Clear mask of 0000000055555555 to remove 8000000000000000 (0)

* clearing CPU 2 really clears bit 2 (CPU 1)
	Clear mask of 0000000055555555 to remove 0000000000000002 (2)

Tested with x86_64-w64-mingw32-gcc 6.4.0 from cygwin on a system
with 64 CPU cores (all fitting in one Windows processor group).
---
 os/os-windows.h | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/os/os-windows.h b/os/os-windows.h
index 520da19..c7941f4 100644
--- a/os/os-windows.h
+++ b/os/os-windows.h
@@ -209,17 +209,17 @@ static inline int fio_getaffinity(int pid, os_cpu_mask_t *mask)
 
 static inline void fio_cpu_clear(os_cpu_mask_t *mask, int cpu)
 {
-	*mask ^= 1 << (cpu-1);
+	*mask &= ~(1ULL << cpu);
 }
 
 static inline void fio_cpu_set(os_cpu_mask_t *mask, int cpu)
 {
-	*mask |= 1 << cpu;
+	*mask |= 1ULL << cpu;
 }
 
 static inline int fio_cpu_isset(os_cpu_mask_t *mask, int cpu)
 {
-	return (*mask & (1U << cpu));
+	return (*mask & (1ULL << cpu));
 }
 
 static inline int fio_cpu_count(os_cpu_mask_t *mask)
-- 
2.9.3

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