From: Mathieu Desnoyers Date: Thu, 16 Jun 2011 19:33:23 +0000 (-0400) Subject: Add bitfield header X-Git-Url: https://git.lttng.org./?a=commitdiff_plain;h=9e7f09242507474b995e1af8f3abf19aad185c43;p=ust.git Add bitfield header Signed-off-by: Mathieu Desnoyers --- diff --git a/include/ust/bitfield.h b/include/ust/bitfield.h new file mode 100644 index 0000000..861e6dc --- /dev/null +++ b/include/ust/bitfield.h @@ -0,0 +1,400 @@ +#ifndef _BABELTRACE_BITFIELD_H +#define _BABELTRACE_BITFIELD_H + +/* + * BabelTrace + * + * Bitfields read/write functions. + * + * Copyright 2010 - Mathieu Desnoyers + * + * 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 */