From: Denis Kenzior <denkenz@gmail.com>
To: ell@lists.linux.dev
Cc: Denis Kenzior <denkenz@gmail.com>
Subject: [PATCH v2 2/4] util: Add L_BIT_{SET|CLEAR|TEST} macros
Date: Tue, 16 Apr 2024 09:24:53 -0500 [thread overview]
Message-ID: <20240416142458.3353383-2-denkenz@gmail.com> (raw)
In-Reply-To: <20240416142458.3353383-1-denkenz@gmail.com>
These macros support arbitrarily sized bitmaps using any integer data
type. It is thus possible to write code like this:
uint64_t bitmap = 0;
uint8_t array[4] = {};
bool r;
L_BIT_SET(&bitmap, 63);
r = L_BIT_TEST(&bitmap, 0);
L_BIT_SET(array, 25);
r = L_BIT_TEST(array, 31);
---
ell/util.h | 30 ++++++++++++++++++++++++++++++
1 file changed, 30 insertions(+)
diff --git a/ell/util.h b/ell/util.h
index 237ea4824b06..ed0bbe845656 100644
--- a/ell/util.h
+++ b/ell/util.h
@@ -366,6 +366,36 @@ inline __attribute__((always_inline)) void _l_close_cleanup(void *p)
(__v && __elems[__i] && \
!strcmp(__v, __elems[__i])), ##__VA_ARGS__)
+#define _L_BIT_TO_MASK(bits, nr) __extension__ ({ \
+ typeof(*(bits)) _one = 1U; \
+ const unsigned int _shift = (nr) % (sizeof(_one) * 8); \
+ _one << _shift; \
+})
+
+#define _L_BIT_TO_OFFSET(bits, nr) __extension__ ({ \
+ __auto_type _bits = (bits); \
+ const size_t _offset = (nr) / (sizeof(*_bits) * 8); \
+ _bits + _offset; \
+})
+
+#define L_BIT_SET(bits, nr) __extension__ ({ \
+ size_t _nr = (nr); \
+ __auto_type _offset = _L_BIT_TO_OFFSET(bits, _nr); \
+ *_offset |= _L_BIT_TO_MASK(_offset, _nr); \
+})
+
+#define L_BIT_CLEAR(bits, nr) __extension__ ({ \
+ size_t _nr = (nr); \
+ __auto_type _offset = _L_BIT_TO_OFFSET(bits, _nr); \
+ *_offset &= ~_L_BIT_TO_MASK(_offset, _nr); \
+})
+
+#define L_BIT_TEST(bits, nr) __extension__ ({ \
+ size_t _nr = (nr); \
+ __auto_type _offset = _L_BIT_TO_OFFSET(bits, _nr); \
+ (*_offset & _L_BIT_TO_MASK(_offset, _nr)) != 0; \
+})
+
/*
* Taken from https://github.com/chmike/cst_time_memcmp, adding a volatile to
* ensure the compiler does not try to optimize the constant time behavior.
--
2.44.0
next prev parent reply other threads:[~2024-04-16 14:25 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-04-16 14:24 [PATCH v2 1/4] util: Remove confusing static keyword use Denis Kenzior
2024-04-16 14:24 ` Denis Kenzior [this message]
2024-04-16 14:24 ` [PATCH v2 3/4] util: Add L_BITS_{SET|CLEAR} Denis Kenzior
2024-04-16 14:24 ` [PATCH v2 4/4] unit: Add tests for the new bitmap utilities Denis Kenzior
2024-04-16 19:07 ` [PATCH v2 1/4] util: Remove confusing static keyword use Denis Kenzior
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