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lttng lib: portable bitfield read/write header
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This commit is contained in:
Mathieu Desnoyers
committed by
Greg Kroah-Hartman
Greg Kroah-Hartman
parent
c844b2f5cf
commit
7430010ec5
400
drivers/staging/lttng/lib/bitfield.h
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400
drivers/staging/lttng/lib/bitfield.h
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@@ -0,0 +1,400 @@
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#ifndef _BABELTRACE_BITFIELD_H
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#define _BABELTRACE_BITFIELD_H
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/*
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* BabelTrace
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*
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* Bitfields read/write functions.
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*
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* Copyright 2010 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the "Software"), to deal
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* in the Software without restriction, including without limitation the rights
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* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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* copies of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in
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* all copies or substantial portions of the Software.
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*/
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#include "../ltt-endian.h"
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#ifndef CHAR_BIT
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#define CHAR_BIT 8
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#endif
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/* We can't shift a int from 32 bit, >> 32 and << 32 on int is undefined */
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#define _bt_piecewise_rshift(_v, _shift) \
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({ \
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typeof(_v) ___v = (_v); \
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typeof(_shift) ___shift = (_shift); \
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unsigned long sb = (___shift) / (sizeof(___v) * CHAR_BIT - 1); \
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unsigned long final = (___shift) % (sizeof(___v) * CHAR_BIT - 1); \
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\
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for (; sb; sb--) \
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___v >>= sizeof(___v) * CHAR_BIT - 1; \
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___v >>= final; \
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})
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#define _bt_piecewise_lshift(_v, _shift) \
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({ \
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typeof(_v) ___v = (_v); \
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typeof(_shift) ___shift = (_shift); \
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unsigned long sb = (___shift) / (sizeof(___v) * CHAR_BIT - 1); \
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unsigned long final = (___shift) % (sizeof(___v) * CHAR_BIT - 1); \
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\
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for (; sb; sb--) \
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___v <<= sizeof(___v) * CHAR_BIT - 1; \
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___v <<= final; \
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})
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#define _bt_is_signed_type(type) (((type)(-1)) < 0)
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#define _bt_unsigned_cast(type, v) \
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({ \
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(sizeof(v) < sizeof(type)) ? \
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((type) (v)) & (~(~(type) 0 << (sizeof(v) * CHAR_BIT))) : \
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(type) (v); \
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})
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/*
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* bt_bitfield_write - write integer to a bitfield in native endianness
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*
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* Save integer to the bitfield, which starts at the "start" bit, has "len"
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* bits.
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* The inside of a bitfield is from high bits to low bits.
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* Uses native endianness.
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* For unsigned "v", pad MSB with 0 if bitfield is larger than v.
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* For signed "v", sign-extend v if bitfield is larger than v.
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*
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* On little endian, bytes are placed from the less significant to the most
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* significant. Also, consecutive bitfields are placed from lower bits to higher
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* bits.
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*
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* On big endian, bytes are places from most significant to less significant.
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* Also, consecutive bitfields are placed from higher to lower bits.
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*/
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#define _bt_bitfield_write_le(_ptr, type, _start, _length, _v) \
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do { \
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typeof(_v) __v = (_v); \
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type *__ptr = (void *) (_ptr); \
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unsigned long __start = (_start), __length = (_length); \
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type mask, cmask; \
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unsigned long ts = sizeof(type) * CHAR_BIT; /* type size */ \
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unsigned long start_unit, end_unit, this_unit; \
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unsigned long end, cshift; /* cshift is "complement shift" */ \
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\
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if (!__length) \
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break; \
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\
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end = __start + __length; \
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start_unit = __start / ts; \
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end_unit = (end + (ts - 1)) / ts; \
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\
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/* Trim v high bits */ \
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if (__length < sizeof(__v) * CHAR_BIT) \
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__v &= ~((~(typeof(__v)) 0) << __length); \
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\
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/* We can now append v with a simple "or", shift it piece-wise */ \
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this_unit = start_unit; \
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if (start_unit == end_unit - 1) { \
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mask = ~((~(type) 0) << (__start % ts)); \
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if (end % ts) \
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mask |= (~(type) 0) << (end % ts); \
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cmask = (type) __v << (__start % ts); \
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cmask &= ~mask; \
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__ptr[this_unit] &= mask; \
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__ptr[this_unit] |= cmask; \
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break; \
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} \
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if (__start % ts) { \
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cshift = __start % ts; \
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mask = ~((~(type) 0) << cshift); \
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cmask = (type) __v << cshift; \
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cmask &= ~mask; \
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__ptr[this_unit] &= mask; \
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__ptr[this_unit] |= cmask; \
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__v = _bt_piecewise_rshift(__v, ts - cshift); \
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__start += ts - cshift; \
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this_unit++; \
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} \
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for (; this_unit < end_unit - 1; this_unit++) { \
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__ptr[this_unit] = (type) __v; \
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__v = _bt_piecewise_rshift(__v, ts); \
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__start += ts; \
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} \
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if (end % ts) { \
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mask = (~(type) 0) << (end % ts); \
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cmask = (type) __v; \
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cmask &= ~mask; \
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__ptr[this_unit] &= mask; \
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__ptr[this_unit] |= cmask; \
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} else \
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__ptr[this_unit] = (type) __v; \
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} while (0)
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#define _bt_bitfield_write_be(_ptr, type, _start, _length, _v) \
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do { \
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typeof(_v) __v = (_v); \
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type *__ptr = (void *) (_ptr); \
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unsigned long __start = (_start), __length = (_length); \
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type mask, cmask; \
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unsigned long ts = sizeof(type) * CHAR_BIT; /* type size */ \
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unsigned long start_unit, end_unit, this_unit; \
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unsigned long end, cshift; /* cshift is "complement shift" */ \
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\
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if (!__length) \
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break; \
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\
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end = __start + __length; \
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start_unit = __start / ts; \
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end_unit = (end + (ts - 1)) / ts; \
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\
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/* Trim v high bits */ \
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if (__length < sizeof(__v) * CHAR_BIT) \
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__v &= ~((~(typeof(__v)) 0) << __length); \
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\
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/* We can now append v with a simple "or", shift it piece-wise */ \
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this_unit = end_unit - 1; \
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if (start_unit == end_unit - 1) { \
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mask = ~((~(type) 0) << ((ts - (end % ts)) % ts)); \
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if (__start % ts) \
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mask |= (~((type) 0)) << (ts - (__start % ts)); \
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cmask = (type) __v << ((ts - (end % ts)) % ts); \
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cmask &= ~mask; \
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__ptr[this_unit] &= mask; \
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__ptr[this_unit] |= cmask; \
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break; \
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} \
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if (end % ts) { \
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cshift = end % ts; \
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mask = ~((~(type) 0) << (ts - cshift)); \
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cmask = (type) __v << (ts - cshift); \
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cmask &= ~mask; \
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__ptr[this_unit] &= mask; \
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__ptr[this_unit] |= cmask; \
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__v = _bt_piecewise_rshift(__v, cshift); \
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end -= cshift; \
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this_unit--; \
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} \
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for (; (long) this_unit >= (long) start_unit + 1; this_unit--) { \
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__ptr[this_unit] = (type) __v; \
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__v = _bt_piecewise_rshift(__v, ts); \
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end -= ts; \
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} \
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if (__start % ts) { \
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mask = (~(type) 0) << (ts - (__start % ts)); \
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cmask = (type) __v; \
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cmask &= ~mask; \
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__ptr[this_unit] &= mask; \
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__ptr[this_unit] |= cmask; \
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} else \
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__ptr[this_unit] = (type) __v; \
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} while (0)
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/*
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* bt_bitfield_write - write integer to a bitfield in native endianness
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* bt_bitfield_write_le - write integer to a bitfield in little endian
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* bt_bitfield_write_be - write integer to a bitfield in big endian
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*/
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#if (__BYTE_ORDER == __LITTLE_ENDIAN)
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#define bt_bitfield_write(ptr, type, _start, _length, _v) \
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_bt_bitfield_write_le(ptr, type, _start, _length, _v)
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#define bt_bitfield_write_le(ptr, type, _start, _length, _v) \
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_bt_bitfield_write_le(ptr, type, _start, _length, _v)
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#define bt_bitfield_write_be(ptr, type, _start, _length, _v) \
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_bt_bitfield_write_be(ptr, unsigned char, _start, _length, _v)
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#elif (__BYTE_ORDER == __BIG_ENDIAN)
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#define bt_bitfield_write(ptr, type, _start, _length, _v) \
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_bt_bitfield_write_be(ptr, type, _start, _length, _v)
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#define bt_bitfield_write_le(ptr, type, _start, _length, _v) \
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_bt_bitfield_write_le(ptr, unsigned char, _start, _length, _v)
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#define bt_bitfield_write_be(ptr, type, _start, _length, _v) \
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_bt_bitfield_write_be(ptr, type, _start, _length, _v)
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#else /* (BYTE_ORDER == PDP_ENDIAN) */
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#error "Byte order not supported"
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#endif
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#define _bt_bitfield_read_le(_ptr, type, _start, _length, _vptr) \
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do { \
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typeof(*(_vptr)) *__vptr = (_vptr); \
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typeof(*__vptr) __v; \
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type *__ptr = (void *) (_ptr); \
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unsigned long __start = (_start), __length = (_length); \
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type mask, cmask; \
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unsigned long ts = sizeof(type) * CHAR_BIT; /* type size */ \
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unsigned long start_unit, end_unit, this_unit; \
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unsigned long end, cshift; /* cshift is "complement shift" */ \
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\
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if (!__length) { \
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*__vptr = 0; \
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break; \
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} \
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\
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end = __start + __length; \
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start_unit = __start / ts; \
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end_unit = (end + (ts - 1)) / ts; \
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\
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this_unit = end_unit - 1; \
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if (_bt_is_signed_type(typeof(__v)) \
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&& (__ptr[this_unit] & ((type) 1 << ((end % ts ? : ts) - 1)))) \
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__v = ~(typeof(__v)) 0; \
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else \
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__v = 0; \
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if (start_unit == end_unit - 1) { \
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cmask = __ptr[this_unit]; \
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cmask >>= (__start % ts); \
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if ((end - __start) % ts) { \
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mask = ~((~(type) 0) << (end - __start)); \
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cmask &= mask; \
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} \
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__v = _bt_piecewise_lshift(__v, end - __start); \
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__v |= _bt_unsigned_cast(typeof(__v), cmask); \
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*__vptr = __v; \
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break; \
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} \
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if (end % ts) { \
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cshift = end % ts; \
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mask = ~((~(type) 0) << cshift); \
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cmask = __ptr[this_unit]; \
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cmask &= mask; \
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__v = _bt_piecewise_lshift(__v, cshift); \
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__v |= _bt_unsigned_cast(typeof(__v), cmask); \
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end -= cshift; \
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this_unit--; \
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} \
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for (; (long) this_unit >= (long) start_unit + 1; this_unit--) { \
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__v = _bt_piecewise_lshift(__v, ts); \
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__v |= _bt_unsigned_cast(typeof(__v), __ptr[this_unit]);\
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end -= ts; \
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} \
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if (__start % ts) { \
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mask = ~((~(type) 0) << (ts - (__start % ts))); \
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cmask = __ptr[this_unit]; \
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cmask >>= (__start % ts); \
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cmask &= mask; \
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__v = _bt_piecewise_lshift(__v, ts - (__start % ts)); \
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__v |= _bt_unsigned_cast(typeof(__v), cmask); \
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} else { \
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__v = _bt_piecewise_lshift(__v, ts); \
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__v |= _bt_unsigned_cast(typeof(__v), __ptr[this_unit]);\
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} \
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*__vptr = __v; \
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} while (0)
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#define _bt_bitfield_read_be(_ptr, type, _start, _length, _vptr) \
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do { \
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typeof(*(_vptr)) *__vptr = (_vptr); \
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typeof(*__vptr) __v; \
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type *__ptr = (void *) (_ptr); \
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unsigned long __start = (_start), __length = (_length); \
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type mask, cmask; \
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unsigned long ts = sizeof(type) * CHAR_BIT; /* type size */ \
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unsigned long start_unit, end_unit, this_unit; \
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unsigned long end, cshift; /* cshift is "complement shift" */ \
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\
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if (!__length) { \
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*__vptr = 0; \
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break; \
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} \
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\
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end = __start + __length; \
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start_unit = __start / ts; \
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end_unit = (end + (ts - 1)) / ts; \
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\
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this_unit = start_unit; \
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if (_bt_is_signed_type(typeof(__v)) \
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&& (__ptr[this_unit] & ((type) 1 << (ts - (__start % ts) - 1)))) \
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__v = ~(typeof(__v)) 0; \
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else \
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__v = 0; \
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if (start_unit == end_unit - 1) { \
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cmask = __ptr[this_unit]; \
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cmask >>= (ts - (end % ts)) % ts; \
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if ((end - __start) % ts) { \
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mask = ~((~(type) 0) << (end - __start)); \
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cmask &= mask; \
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} \
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__v = _bt_piecewise_lshift(__v, end - __start); \
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__v |= _bt_unsigned_cast(typeof(__v), cmask); \
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*__vptr = __v; \
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break; \
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} \
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if (__start % ts) { \
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cshift = __start % ts; \
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mask = ~((~(type) 0) << (ts - cshift)); \
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cmask = __ptr[this_unit]; \
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cmask &= mask; \
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__v = _bt_piecewise_lshift(__v, ts - cshift); \
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__v |= _bt_unsigned_cast(typeof(__v), cmask); \
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__start += ts - cshift; \
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this_unit++; \
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} \
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for (; this_unit < end_unit - 1; this_unit++) { \
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__v = _bt_piecewise_lshift(__v, ts); \
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__v |= _bt_unsigned_cast(typeof(__v), __ptr[this_unit]);\
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__start += ts; \
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} \
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if (end % ts) { \
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mask = ~((~(type) 0) << (end % ts)); \
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cmask = __ptr[this_unit]; \
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cmask >>= ts - (end % ts); \
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cmask &= mask; \
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__v = _bt_piecewise_lshift(__v, end % ts); \
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__v |= _bt_unsigned_cast(typeof(__v), cmask); \
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} else { \
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__v = _bt_piecewise_lshift(__v, ts); \
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__v |= _bt_unsigned_cast(typeof(__v), __ptr[this_unit]);\
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} \
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*__vptr = __v; \
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} while (0)
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/*
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* bt_bitfield_read - read integer from a bitfield in native endianness
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* bt_bitfield_read_le - read integer from a bitfield in little endian
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* bt_bitfield_read_be - read integer from a bitfield in big endian
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*/
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#if (__BYTE_ORDER == __LITTLE_ENDIAN)
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#define bt_bitfield_read(_ptr, type, _start, _length, _vptr) \
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_bt_bitfield_read_le(_ptr, type, _start, _length, _vptr)
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#define bt_bitfield_read_le(_ptr, type, _start, _length, _vptr) \
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_bt_bitfield_read_le(_ptr, type, _start, _length, _vptr)
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#define bt_bitfield_read_be(_ptr, type, _start, _length, _vptr) \
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_bt_bitfield_read_be(_ptr, unsigned char, _start, _length, _vptr)
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#elif (__BYTE_ORDER == __BIG_ENDIAN)
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#define bt_bitfield_read(_ptr, type, _start, _length, _vptr) \
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_bt_bitfield_read_be(_ptr, type, _start, _length, _vptr)
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#define bt_bitfield_read_le(_ptr, type, _start, _length, _vptr) \
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_bt_bitfield_read_le(_ptr, unsigned char, _start, _length, _vptr)
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#define bt_bitfield_read_be(_ptr, type, _start, _length, _vptr) \
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_bt_bitfield_read_be(_ptr, type, _start, _length, _vptr)
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#else /* (__BYTE_ORDER == __PDP_ENDIAN) */
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#error "Byte order not supported"
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#endif
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#endif /* _BABELTRACE_BITFIELD_H */
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