29 lines
1.1 KiB
C
29 lines
1.1 KiB
C
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#include <stdint.h>
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#include <assert.h>
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// Generate a mask with n bits set to 1
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#define LOW_N_BITS(n) (~((~(uintmax_t)0) << (n)))
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#define LOWBIT(x) ((x)&(-(x)))
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// Inserts specified data into a bit segment of any type
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#define PACK_BITFIELD(container, value, start_bit, width) \
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((container) = (((container) & ~((((uintmax_t)1 << (width)) - 1) << (start_bit))) | \
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((((uintmax_t)(value)) & (((uintmax_t)1 << (width)) - 1)) << (start_bit))))
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// Security version
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#define S_PACK_BITFIELD(container, value, start_bit, width) \
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do { \
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assert((width) > 0 && (width) < sizeof(uintmax_t)*8); \
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assert((start_bit) + (width) <= sizeof(container)*8); \
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PACK_BITFIELD(container, value, start_bit, width); \
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} while (0)
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// Extract data
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#define UNPACK_BITFIELD(container, start_bit, width) \
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(((container) >> (start_bit)) & (((uintmax_t)1 << (width)) - 1))
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// Security version
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#define S_UNPACK_BITFIELD(container, start_bit, width) \
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(assert((width) > 0 && (width) < sizeof(uintmax_t)*8), \
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assert((start_bit) + (width) <= sizeof(container)*8), \
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(((container) >> (start_bit)) & (((uintmax_t)1 << (width)) - 1)))
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