From: Denis Kenzior <denkenz@gmail.com>
To: ell@lists.linux.dev
Cc: Denis Kenzior <denkenz@gmail.com>
Subject: [PATCH 2/4] util: Add L_BIT_{SET|CLEAR|TEST} macros
Date: Mon, 15 Apr 2024 14:14:34 -0500 [thread overview]
Message-ID: <20240415191454.3259243-2-denkenz@gmail.com> (raw)
In-Reply-To: <20240415191454.3259243-1-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 | 18 ++++++++++++++++++
1 file changed, 18 insertions(+)
diff --git a/ell/util.h b/ell/util.h
index b5d96754e8ae..53a932c771e6 100644
--- a/ell/util.h
+++ b/ell/util.h
@@ -366,6 +366,24 @@ 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__ ({ \
+ const unsigned int shift = (nr) % (sizeof(*(bits)) * 8); \
+ const typeof(*(bits)) mask = (typeof(*(bits)))1 << shift; \
+ mask; \
+})
+
+#define _L_BIT_TO_OFFSET(bits, nr) \
+ (*((bits) + ((nr) / (sizeof(*(bits)) * 8)))) \
+
+#define L_BIT_SET(bits, nr) \
+ _L_BIT_TO_OFFSET(bits, nr) |= _L_BIT_TO_MASK(bits, nr)
+
+#define L_BIT_CLEAR(bits, nr) \
+ _L_BIT_TO_OFFSET(bits, nr) &= ~_L_BIT_TO_MASK(bits, nr)
+
+#define L_BIT_TEST(bits, nr) \
+ ((~_L_BIT_TO_OFFSET(bits, nr) & _L_BIT_TO_MASK(bits, 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:[~2024-04-15 19:14 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-04-15 19:14 [PATCH 1/4] util: Remove confusing static keyword use Denis Kenzior
2024-04-15 19:14 ` Denis Kenzior [this message]
2024-04-15 19:14 ` [PATCH 3/4] util: Add L_BITS_{SET|CLEAR} Denis Kenzior
2024-04-15 19:14 ` [PATCH 4/4] unit: Add tests for the new bitmap utilities Denis Kenzior
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