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96 lines
2.8 KiB
96 lines
2.8 KiB
/*
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* Copyright © 2015 Samsung Electronics Co., Ltd
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*
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* Permission is hereby granted, free of charge, to any person obtaining
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* a copy of this software and associated documentation files (the
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* "Software"), to deal in the Software without restriction, including
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* without limitation the rights to use, copy, modify, merge, publish,
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* distribute, sublicense, and/or sell copies of the Software, and to
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* permit persons to whom the Software is furnished to do so, subject to
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* the following conditions:
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
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* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
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* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
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* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
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* BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
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* ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
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* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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* SOFTWARE.
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*/
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#ifndef WESTON_HELPERS_H
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#define WESTON_HELPERS_H
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#ifdef __cplusplus
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extern "C" {
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#endif
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/**
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* @file
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* Simple misc helper macros.
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*/
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/**
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* Compile-time computation of number of items in a hardcoded array.
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*
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* @param a the array being measured.
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* @return the number of items hardcoded into the array.
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*/
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#ifndef ARRAY_LENGTH
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#define ARRAY_LENGTH(a) (sizeof (a) / sizeof (a)[0])
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#endif
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/**
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* Returns the smaller of two values.
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*
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* @param x the first item to compare.
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* @param y the second item to compare.
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* @return the value that evaluates to lesser than the other.
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*/
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#ifndef MIN
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#define MIN(x,y) (((x) < (y)) ? (x) : (y))
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#endif
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/**
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* Returns a pointer the the containing struct of a given member item.
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*
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* To demonstrate, the following example retrieves a pointer to
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* `example_container` given only its `destroy_listener` member:
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*
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* @code
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* struct example_container {
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* struct wl_listener destroy_listener;
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* // other members...
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* };
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*
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* void example_container_destroy(struct wl_listener *listener, void *data)
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* {
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* struct example_container *ctr;
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*
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* ctr = wl_container_of(listener, ctr, destroy_listener);
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* // destroy ctr...
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* }
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* @endcode
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*
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* @param ptr A valid pointer to the contained item.
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*
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* @param type A pointer to the type of content that the list item
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* stores. Type does not need be a valid pointer; a null or
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* an uninitialised pointer will suffice.
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*
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* @param member The named location of ptr within the sample type.
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*
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* @return The container for the specified pointer.
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*/
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#ifndef container_of
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#define container_of(ptr, type, member) ({ \
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const __typeof__( ((type *)0)->member ) *__mptr = (ptr); \
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(type *)( (char *)__mptr - offsetof(type,member) );})
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#endif
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#ifdef __cplusplus
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}
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#endif
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#endif /* WESTON_HELPERS_H */
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