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[PATCHv6,1/6] util: introduce MIN_NON_ZERO

Message ID 1414401528-21884-2-git-send-email-pl@kamp.de
State New
Headers show

Commit Message

Peter Lieven Oct. 27, 2014, 9:18 a.m. UTC 
at least in block layer we have the case of limits being defined for a
BlockDriverState. However, in this context often zero (0) has the special
meanining of undefined which means no limit. If two of those limits are
combined and the minimum is needed the minimum function should only return
zero if both parameters are zero.

Signed-off-by: Peter Lieven <pl@kamp.de>
Reviewed-by: Max Reitz <mreitz@redhat.com>
---
 include/qemu/osdep.h |    6 ++++++
 1 file changed, 6 insertions(+)
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Patch

diff --git a/include/qemu/osdep.h b/include/qemu/osdep.h
index 1565404..c032434 100644
--- a/include/qemu/osdep.h
+++ b/include/qemu/osdep.h
@@ -68,6 +68,12 @@  typedef signed int              int_fast16_t;
 #define MAX(a, b) (((a) > (b)) ? (a) : (b))
 #endif
 
+/* Minimum function that returns zero only iff both values are zero.
+ * Intended for use with unsigned values only. */
+#ifndef MIN_NON_ZERO
+#define MIN_NON_ZERO(a, b) (((a) != 0 && (a) < (b)) ? (a) : (b))
+#endif
+
 #ifndef ROUND_UP
 #define ROUND_UP(n,d) (((n) + (d) - 1) & -(d))
 #endif