[PATCH 02/19] lttng lib: portable bitfield read/write header
Mathieu Desnoyers
mathieu.desnoyers at efficios.com
Sat Nov 26 15:03:27 UTC 2011
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers at efficios.com>
---
drivers/staging/lttng/lib/bitfield.h | 400 ++++++++++++++++++++++++++++++++++
1 files changed, 400 insertions(+), 0 deletions(-)
create mode 100644 drivers/staging/lttng/lib/bitfield.h
diff --git a/drivers/staging/lttng/lib/bitfield.h b/drivers/staging/lttng/lib/bitfield.h
new file mode 100644
index 0000000..861e6dc
--- /dev/null
+++ b/drivers/staging/lttng/lib/bitfield.h
@@ -0,0 +1,400 @@
+#ifndef _BABELTRACE_BITFIELD_H
+#define _BABELTRACE_BITFIELD_H
+
+/*
+ * BabelTrace
+ *
+ * Bitfields read/write functions.
+ *
+ * Copyright 2010 - Mathieu Desnoyers <mathieu.desnoyers at efficios.com>
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ */
+
+#include "../ltt-endian.h"
+
+#ifndef CHAR_BIT
+#define CHAR_BIT 8
+#endif
+
+/* We can't shift a int from 32 bit, >> 32 and << 32 on int is undefined */
+#define _bt_piecewise_rshift(_v, _shift) \
+({ \
+ typeof(_v) ___v = (_v); \
+ typeof(_shift) ___shift = (_shift); \
+ unsigned long sb = (___shift) / (sizeof(___v) * CHAR_BIT - 1); \
+ unsigned long final = (___shift) % (sizeof(___v) * CHAR_BIT - 1); \
+ \
+ for (; sb; sb--) \
+ ___v >>= sizeof(___v) * CHAR_BIT - 1; \
+ ___v >>= final; \
+})
+
+#define _bt_piecewise_lshift(_v, _shift) \
+({ \
+ typeof(_v) ___v = (_v); \
+ typeof(_shift) ___shift = (_shift); \
+ unsigned long sb = (___shift) / (sizeof(___v) * CHAR_BIT - 1); \
+ unsigned long final = (___shift) % (sizeof(___v) * CHAR_BIT - 1); \
+ \
+ for (; sb; sb--) \
+ ___v <<= sizeof(___v) * CHAR_BIT - 1; \
+ ___v <<= final; \
+})
+
+#define _bt_is_signed_type(type) (((type)(-1)) < 0)
+
+#define _bt_unsigned_cast(type, v) \
+({ \
+ (sizeof(v) < sizeof(type)) ? \
+ ((type) (v)) & (~(~(type) 0 << (sizeof(v) * CHAR_BIT))) : \
+ (type) (v); \
+})
+
+/*
+ * bt_bitfield_write - write integer to a bitfield in native endianness
+ *
+ * Save integer to the bitfield, which starts at the "start" bit, has "len"
+ * bits.
+ * The inside of a bitfield is from high bits to low bits.
+ * Uses native endianness.
+ * For unsigned "v", pad MSB with 0 if bitfield is larger than v.
+ * For signed "v", sign-extend v if bitfield is larger than v.
+ *
+ * On little endian, bytes are placed from the less significant to the most
+ * significant. Also, consecutive bitfields are placed from lower bits to higher
+ * bits.
+ *
+ * On big endian, bytes are places from most significant to less significant.
+ * Also, consecutive bitfields are placed from higher to lower bits.
+ */
+
+#define _bt_bitfield_write_le(_ptr, type, _start, _length, _v) \
+do { \
+ typeof(_v) __v = (_v); \
+ type *__ptr = (void *) (_ptr); \
+ unsigned long __start = (_start), __length = (_length); \
+ type mask, cmask; \
+ unsigned long ts = sizeof(type) * CHAR_BIT; /* type size */ \
+ unsigned long start_unit, end_unit, this_unit; \
+ unsigned long end, cshift; /* cshift is "complement shift" */ \
+ \
+ if (!__length) \
+ break; \
+ \
+ end = __start + __length; \
+ start_unit = __start / ts; \
+ end_unit = (end + (ts - 1)) / ts; \
+ \
+ /* Trim v high bits */ \
+ if (__length < sizeof(__v) * CHAR_BIT) \
+ __v &= ~((~(typeof(__v)) 0) << __length); \
+ \
+ /* We can now append v with a simple "or", shift it piece-wise */ \
+ this_unit = start_unit; \
+ if (start_unit == end_unit - 1) { \
+ mask = ~((~(type) 0) << (__start % ts)); \
+ if (end % ts) \
+ mask |= (~(type) 0) << (end % ts); \
+ cmask = (type) __v << (__start % ts); \
+ cmask &= ~mask; \
+ __ptr[this_unit] &= mask; \
+ __ptr[this_unit] |= cmask; \
+ break; \
+ } \
+ if (__start % ts) { \
+ cshift = __start % ts; \
+ mask = ~((~(type) 0) << cshift); \
+ cmask = (type) __v << cshift; \
+ cmask &= ~mask; \
+ __ptr[this_unit] &= mask; \
+ __ptr[this_unit] |= cmask; \
+ __v = _bt_piecewise_rshift(__v, ts - cshift); \
+ __start += ts - cshift; \
+ this_unit++; \
+ } \
+ for (; this_unit < end_unit - 1; this_unit++) { \
+ __ptr[this_unit] = (type) __v; \
+ __v = _bt_piecewise_rshift(__v, ts); \
+ __start += ts; \
+ } \
+ if (end % ts) { \
+ mask = (~(type) 0) << (end % ts); \
+ cmask = (type) __v; \
+ cmask &= ~mask; \
+ __ptr[this_unit] &= mask; \
+ __ptr[this_unit] |= cmask; \
+ } else \
+ __ptr[this_unit] = (type) __v; \
+} while (0)
+
+#define _bt_bitfield_write_be(_ptr, type, _start, _length, _v) \
+do { \
+ typeof(_v) __v = (_v); \
+ type *__ptr = (void *) (_ptr); \
+ unsigned long __start = (_start), __length = (_length); \
+ type mask, cmask; \
+ unsigned long ts = sizeof(type) * CHAR_BIT; /* type size */ \
+ unsigned long start_unit, end_unit, this_unit; \
+ unsigned long end, cshift; /* cshift is "complement shift" */ \
+ \
+ if (!__length) \
+ break; \
+ \
+ end = __start + __length; \
+ start_unit = __start / ts; \
+ end_unit = (end + (ts - 1)) / ts; \
+ \
+ /* Trim v high bits */ \
+ if (__length < sizeof(__v) * CHAR_BIT) \
+ __v &= ~((~(typeof(__v)) 0) << __length); \
+ \
+ /* We can now append v with a simple "or", shift it piece-wise */ \
+ this_unit = end_unit - 1; \
+ if (start_unit == end_unit - 1) { \
+ mask = ~((~(type) 0) << ((ts - (end % ts)) % ts)); \
+ if (__start % ts) \
+ mask |= (~((type) 0)) << (ts - (__start % ts)); \
+ cmask = (type) __v << ((ts - (end % ts)) % ts); \
+ cmask &= ~mask; \
+ __ptr[this_unit] &= mask; \
+ __ptr[this_unit] |= cmask; \
+ break; \
+ } \
+ if (end % ts) { \
+ cshift = end % ts; \
+ mask = ~((~(type) 0) << (ts - cshift)); \
+ cmask = (type) __v << (ts - cshift); \
+ cmask &= ~mask; \
+ __ptr[this_unit] &= mask; \
+ __ptr[this_unit] |= cmask; \
+ __v = _bt_piecewise_rshift(__v, cshift); \
+ end -= cshift; \
+ this_unit--; \
+ } \
+ for (; (long) this_unit >= (long) start_unit + 1; this_unit--) { \
+ __ptr[this_unit] = (type) __v; \
+ __v = _bt_piecewise_rshift(__v, ts); \
+ end -= ts; \
+ } \
+ if (__start % ts) { \
+ mask = (~(type) 0) << (ts - (__start % ts)); \
+ cmask = (type) __v; \
+ cmask &= ~mask; \
+ __ptr[this_unit] &= mask; \
+ __ptr[this_unit] |= cmask; \
+ } else \
+ __ptr[this_unit] = (type) __v; \
+} while (0)
+
+/*
+ * bt_bitfield_write - write integer to a bitfield in native endianness
+ * bt_bitfield_write_le - write integer to a bitfield in little endian
+ * bt_bitfield_write_be - write integer to a bitfield in big endian
+ */
+
+#if (__BYTE_ORDER == __LITTLE_ENDIAN)
+
+#define bt_bitfield_write(ptr, type, _start, _length, _v) \
+ _bt_bitfield_write_le(ptr, type, _start, _length, _v)
+
+#define bt_bitfield_write_le(ptr, type, _start, _length, _v) \
+ _bt_bitfield_write_le(ptr, type, _start, _length, _v)
+
+#define bt_bitfield_write_be(ptr, type, _start, _length, _v) \
+ _bt_bitfield_write_be(ptr, unsigned char, _start, _length, _v)
+
+#elif (__BYTE_ORDER == __BIG_ENDIAN)
+
+#define bt_bitfield_write(ptr, type, _start, _length, _v) \
+ _bt_bitfield_write_be(ptr, type, _start, _length, _v)
+
+#define bt_bitfield_write_le(ptr, type, _start, _length, _v) \
+ _bt_bitfield_write_le(ptr, unsigned char, _start, _length, _v)
+
+#define bt_bitfield_write_be(ptr, type, _start, _length, _v) \
+ _bt_bitfield_write_be(ptr, type, _start, _length, _v)
+
+#else /* (BYTE_ORDER == PDP_ENDIAN) */
+
+#error "Byte order not supported"
+
+#endif
+
+#define _bt_bitfield_read_le(_ptr, type, _start, _length, _vptr) \
+do { \
+ typeof(*(_vptr)) *__vptr = (_vptr); \
+ typeof(*__vptr) __v; \
+ type *__ptr = (void *) (_ptr); \
+ unsigned long __start = (_start), __length = (_length); \
+ type mask, cmask; \
+ unsigned long ts = sizeof(type) * CHAR_BIT; /* type size */ \
+ unsigned long start_unit, end_unit, this_unit; \
+ unsigned long end, cshift; /* cshift is "complement shift" */ \
+ \
+ if (!__length) { \
+ *__vptr = 0; \
+ break; \
+ } \
+ \
+ end = __start + __length; \
+ start_unit = __start / ts; \
+ end_unit = (end + (ts - 1)) / ts; \
+ \
+ this_unit = end_unit - 1; \
+ if (_bt_is_signed_type(typeof(__v)) \
+ && (__ptr[this_unit] & ((type) 1 << ((end % ts ? : ts) - 1)))) \
+ __v = ~(typeof(__v)) 0; \
+ else \
+ __v = 0; \
+ if (start_unit == end_unit - 1) { \
+ cmask = __ptr[this_unit]; \
+ cmask >>= (__start % ts); \
+ if ((end - __start) % ts) { \
+ mask = ~((~(type) 0) << (end - __start)); \
+ cmask &= mask; \
+ } \
+ __v = _bt_piecewise_lshift(__v, end - __start); \
+ __v |= _bt_unsigned_cast(typeof(__v), cmask); \
+ *__vptr = __v; \
+ break; \
+ } \
+ if (end % ts) { \
+ cshift = end % ts; \
+ mask = ~((~(type) 0) << cshift); \
+ cmask = __ptr[this_unit]; \
+ cmask &= mask; \
+ __v = _bt_piecewise_lshift(__v, cshift); \
+ __v |= _bt_unsigned_cast(typeof(__v), cmask); \
+ end -= cshift; \
+ this_unit--; \
+ } \
+ for (; (long) this_unit >= (long) start_unit + 1; this_unit--) { \
+ __v = _bt_piecewise_lshift(__v, ts); \
+ __v |= _bt_unsigned_cast(typeof(__v), __ptr[this_unit]);\
+ end -= ts; \
+ } \
+ if (__start % ts) { \
+ mask = ~((~(type) 0) << (ts - (__start % ts))); \
+ cmask = __ptr[this_unit]; \
+ cmask >>= (__start % ts); \
+ cmask &= mask; \
+ __v = _bt_piecewise_lshift(__v, ts - (__start % ts)); \
+ __v |= _bt_unsigned_cast(typeof(__v), cmask); \
+ } else { \
+ __v = _bt_piecewise_lshift(__v, ts); \
+ __v |= _bt_unsigned_cast(typeof(__v), __ptr[this_unit]);\
+ } \
+ *__vptr = __v; \
+} while (0)
+
+#define _bt_bitfield_read_be(_ptr, type, _start, _length, _vptr) \
+do { \
+ typeof(*(_vptr)) *__vptr = (_vptr); \
+ typeof(*__vptr) __v; \
+ type *__ptr = (void *) (_ptr); \
+ unsigned long __start = (_start), __length = (_length); \
+ type mask, cmask; \
+ unsigned long ts = sizeof(type) * CHAR_BIT; /* type size */ \
+ unsigned long start_unit, end_unit, this_unit; \
+ unsigned long end, cshift; /* cshift is "complement shift" */ \
+ \
+ if (!__length) { \
+ *__vptr = 0; \
+ break; \
+ } \
+ \
+ end = __start + __length; \
+ start_unit = __start / ts; \
+ end_unit = (end + (ts - 1)) / ts; \
+ \
+ this_unit = start_unit; \
+ if (_bt_is_signed_type(typeof(__v)) \
+ && (__ptr[this_unit] & ((type) 1 << (ts - (__start % ts) - 1)))) \
+ __v = ~(typeof(__v)) 0; \
+ else \
+ __v = 0; \
+ if (start_unit == end_unit - 1) { \
+ cmask = __ptr[this_unit]; \
+ cmask >>= (ts - (end % ts)) % ts; \
+ if ((end - __start) % ts) { \
+ mask = ~((~(type) 0) << (end - __start)); \
+ cmask &= mask; \
+ } \
+ __v = _bt_piecewise_lshift(__v, end - __start); \
+ __v |= _bt_unsigned_cast(typeof(__v), cmask); \
+ *__vptr = __v; \
+ break; \
+ } \
+ if (__start % ts) { \
+ cshift = __start % ts; \
+ mask = ~((~(type) 0) << (ts - cshift)); \
+ cmask = __ptr[this_unit]; \
+ cmask &= mask; \
+ __v = _bt_piecewise_lshift(__v, ts - cshift); \
+ __v |= _bt_unsigned_cast(typeof(__v), cmask); \
+ __start += ts - cshift; \
+ this_unit++; \
+ } \
+ for (; this_unit < end_unit - 1; this_unit++) { \
+ __v = _bt_piecewise_lshift(__v, ts); \
+ __v |= _bt_unsigned_cast(typeof(__v), __ptr[this_unit]);\
+ __start += ts; \
+ } \
+ if (end % ts) { \
+ mask = ~((~(type) 0) << (end % ts)); \
+ cmask = __ptr[this_unit]; \
+ cmask >>= ts - (end % ts); \
+ cmask &= mask; \
+ __v = _bt_piecewise_lshift(__v, end % ts); \
+ __v |= _bt_unsigned_cast(typeof(__v), cmask); \
+ } else { \
+ __v = _bt_piecewise_lshift(__v, ts); \
+ __v |= _bt_unsigned_cast(typeof(__v), __ptr[this_unit]);\
+ } \
+ *__vptr = __v; \
+} while (0)
+
+/*
+ * bt_bitfield_read - read integer from a bitfield in native endianness
+ * bt_bitfield_read_le - read integer from a bitfield in little endian
+ * bt_bitfield_read_be - read integer from a bitfield in big endian
+ */
+
+#if (__BYTE_ORDER == __LITTLE_ENDIAN)
+
+#define bt_bitfield_read(_ptr, type, _start, _length, _vptr) \
+ _bt_bitfield_read_le(_ptr, type, _start, _length, _vptr)
+
+#define bt_bitfield_read_le(_ptr, type, _start, _length, _vptr) \
+ _bt_bitfield_read_le(_ptr, type, _start, _length, _vptr)
+
+#define bt_bitfield_read_be(_ptr, type, _start, _length, _vptr) \
+ _bt_bitfield_read_be(_ptr, unsigned char, _start, _length, _vptr)
+
+#elif (__BYTE_ORDER == __BIG_ENDIAN)
+
+#define bt_bitfield_read(_ptr, type, _start, _length, _vptr) \
+ _bt_bitfield_read_be(_ptr, type, _start, _length, _vptr)
+
+#define bt_bitfield_read_le(_ptr, type, _start, _length, _vptr) \
+ _bt_bitfield_read_le(_ptr, unsigned char, _start, _length, _vptr)
+
+#define bt_bitfield_read_be(_ptr, type, _start, _length, _vptr) \
+ _bt_bitfield_read_be(_ptr, type, _start, _length, _vptr)
+
+#else /* (__BYTE_ORDER == __PDP_ENDIAN) */
+
+#error "Byte order not supported"
+
+#endif
+
+#endif /* _BABELTRACE_BITFIELD_H */
--
1.7.2.5
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