Annotation of embedaddon/libiconv/srclib/intprops.h, revision 1.1.1.2
1.1 misho 1: /* intprops.h -- properties of integer types
2:
1.1.1.2 ! misho 3: Copyright (C) 2001-2005, 2009-2011 Free Software Foundation, Inc.
1.1 misho 4:
5: This program is free software: you can redistribute it and/or modify
6: it under the terms of the GNU General Public License as published by
7: the Free Software Foundation; either version 3 of the License, or
8: (at your option) any later version.
9:
10: This program is distributed in the hope that it will be useful,
11: but WITHOUT ANY WARRANTY; without even the implied warranty of
12: MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13: GNU General Public License for more details.
14:
15: You should have received a copy of the GNU General Public License
16: along with this program. If not, see <http://www.gnu.org/licenses/>. */
17:
18: /* Written by Paul Eggert. */
19:
1.1.1.2 ! misho 20: #ifndef _GL_INTPROPS_H
! 21: #define _GL_INTPROPS_H
! 22:
1.1 misho 23: #include <limits.h>
24:
1.1.1.2 ! misho 25: /* Return an integer value, converted to the same type as the integer
! 26: expression E after integer type promotion. V is the unconverted value. */
! 27: #define _GL_INT_CONVERT(e, v) (0 * (e) + (v))
! 28:
! 29: /* Act like _GL_INT_CONVERT (E, -V) but work around a bug in IRIX 6.5 cc; see
! 30: <http://lists.gnu.org/archive/html/bug-gnulib/2011-05/msg00406.html>. */
! 31: #define _GL_INT_NEGATE_CONVERT(e, v) (0 * (e) - (v))
! 32:
1.1 misho 33: /* The extra casts in the following macros work around compiler bugs,
34: e.g., in Cray C 5.0.3.0. */
35:
36: /* True if the arithmetic type T is an integer type. bool counts as
37: an integer. */
38: #define TYPE_IS_INTEGER(t) ((t) 1.5 == 1)
39:
40: /* True if negative values of the signed integer type T use two's
41: complement, ones' complement, or signed magnitude representation,
42: respectively. Much GNU code assumes two's complement, but some
43: people like to be portable to all possible C hosts. */
44: #define TYPE_TWOS_COMPLEMENT(t) ((t) ~ (t) 0 == (t) -1)
45: #define TYPE_ONES_COMPLEMENT(t) ((t) ~ (t) 0 == 0)
46: #define TYPE_SIGNED_MAGNITUDE(t) ((t) ~ (t) 0 < (t) -1)
47:
1.1.1.2 ! misho 48: /* True if the signed integer expression E uses two's complement. */
! 49: #define _GL_INT_TWOS_COMPLEMENT(e) (~ _GL_INT_CONVERT (e, 0) == -1)
! 50:
1.1 misho 51: /* True if the arithmetic type T is signed. */
52: #define TYPE_SIGNED(t) (! ((t) 0 < (t) -1))
53:
1.1.1.2 ! misho 54: /* Return 1 if the integer expression E, after integer promotion, has
! 55: a signed type. */
! 56: #define _GL_INT_SIGNED(e) (_GL_INT_NEGATE_CONVERT (e, 1) < 0)
! 57:
! 58:
! 59: /* Minimum and maximum values for integer types and expressions. These
1.1 misho 60: macros have undefined behavior if T is signed and has padding bits.
61: If this is a problem for you, please let us know how to fix it for
62: your host. */
1.1.1.2 ! misho 63:
! 64: /* The maximum and minimum values for the integer type T. */
! 65: #define TYPE_MINIMUM(t) \
! 66: ((t) (! TYPE_SIGNED (t) \
! 67: ? (t) 0 \
! 68: : TYPE_SIGNED_MAGNITUDE (t) \
! 69: ? ~ (t) 0 \
! 70: : ~ TYPE_MAXIMUM (t)))
! 71: #define TYPE_MAXIMUM(t) \
! 72: ((t) (! TYPE_SIGNED (t) \
! 73: ? (t) -1 \
! 74: : ((((t) 1 << (sizeof (t) * CHAR_BIT - 2)) - 1) * 2 + 1)))
! 75:
! 76: /* The maximum and minimum values for the type of the expression E,
! 77: after integer promotion. E should not have side effects. */
! 78: #define _GL_INT_MINIMUM(e) \
! 79: (_GL_INT_SIGNED (e) \
! 80: ? - _GL_INT_TWOS_COMPLEMENT (e) - _GL_SIGNED_INT_MAXIMUM (e) \
! 81: : _GL_INT_CONVERT (e, 0))
! 82: #define _GL_INT_MAXIMUM(e) \
! 83: (_GL_INT_SIGNED (e) \
! 84: ? _GL_SIGNED_INT_MAXIMUM (e) \
! 85: : _GL_INT_NEGATE_CONVERT (e, 1))
! 86: #define _GL_SIGNED_INT_MAXIMUM(e) \
! 87: (((_GL_INT_CONVERT (e, 1) << (sizeof ((e) + 0) * CHAR_BIT - 2)) - 1) * 2 + 1)
! 88:
! 89:
! 90: /* Return 1 if the __typeof__ keyword works. This could be done by
! 91: 'configure', but for now it's easier to do it by hand. */
! 92: #if 2 <= __GNUC__ || 0x5110 <= __SUNPRO_C
! 93: # define _GL_HAVE___TYPEOF__ 1
1.1 misho 94: #else
1.1.1.2 ! misho 95: # define _GL_HAVE___TYPEOF__ 0
1.1 misho 96: #endif
97:
1.1.1.2 ! misho 98: /* Return 1 if the integer type or expression T might be signed. Return 0
! 99: if it is definitely unsigned. This macro does not evaluate its argument,
! 100: and expands to an integer constant expression. */
! 101: #if _GL_HAVE___TYPEOF__
! 102: # define _GL_SIGNED_TYPE_OR_EXPR(t) TYPE_SIGNED (__typeof__ (t))
! 103: #else
! 104: # define _GL_SIGNED_TYPE_OR_EXPR(t) 1
! 105: #endif
! 106:
! 107: /* Bound on length of the string representing an unsigned integer
! 108: value representable in B bits. log10 (2.0) < 146/485. The
! 109: smallest value of B where this bound is not tight is 2621. */
! 110: #define INT_BITS_STRLEN_BOUND(b) (((b) * 146 + 484) / 485)
! 111:
1.1 misho 112: /* Bound on length of the string representing an integer type or expression T.
1.1.1.2 ! misho 113: Subtract 1 for the sign bit if T is signed, and then add 1 more for
! 114: a minus sign if needed.
! 115:
! 116: Because _GL_SIGNED_TYPE_OR_EXPR sometimes returns 0 when its argument is
! 117: signed, this macro may overestimate the true bound by one byte when
! 118: applied to unsigned types of size 2, 4, 16, ... bytes. */
! 119: #define INT_STRLEN_BOUND(t) \
! 120: (INT_BITS_STRLEN_BOUND (sizeof (t) * CHAR_BIT \
! 121: - _GL_SIGNED_TYPE_OR_EXPR (t)) \
! 122: + _GL_SIGNED_TYPE_OR_EXPR (t))
1.1 misho 123:
124: /* Bound on buffer size needed to represent an integer type or expression T,
125: including the terminating null. */
126: #define INT_BUFSIZE_BOUND(t) (INT_STRLEN_BOUND (t) + 1)
1.1.1.2 ! misho 127:
! 128:
! 129: /* Range overflow checks.
! 130:
! 131: The INT_<op>_RANGE_OVERFLOW macros return 1 if the corresponding C
! 132: operators might not yield numerically correct answers due to
! 133: arithmetic overflow. They do not rely on undefined or
! 134: implementation-defined behavior. Their implementations are simple
! 135: and straightforward, but they are a bit harder to use than the
! 136: INT_<op>_OVERFLOW macros described below.
! 137:
! 138: Example usage:
! 139:
! 140: long int i = ...;
! 141: long int j = ...;
! 142: if (INT_MULTIPLY_RANGE_OVERFLOW (i, j, LONG_MIN, LONG_MAX))
! 143: printf ("multiply would overflow");
! 144: else
! 145: printf ("product is %ld", i * j);
! 146:
! 147: Restrictions on *_RANGE_OVERFLOW macros:
! 148:
! 149: These macros do not check for all possible numerical problems or
! 150: undefined or unspecified behavior: they do not check for division
! 151: by zero, for bad shift counts, or for shifting negative numbers.
! 152:
! 153: These macros may evaluate their arguments zero or multiple times,
! 154: so the arguments should not have side effects. The arithmetic
! 155: arguments (including the MIN and MAX arguments) must be of the same
! 156: integer type after the usual arithmetic conversions, and the type
! 157: must have minimum value MIN and maximum MAX. Unsigned types should
! 158: use a zero MIN of the proper type.
! 159:
! 160: These macros are tuned for constant MIN and MAX. For commutative
! 161: operations such as A + B, they are also tuned for constant B. */
! 162:
! 163: /* Return 1 if A + B would overflow in [MIN,MAX] arithmetic.
! 164: See above for restrictions. */
! 165: #define INT_ADD_RANGE_OVERFLOW(a, b, min, max) \
! 166: ((b) < 0 \
! 167: ? (a) < (min) - (b) \
! 168: : (max) - (b) < (a))
! 169:
! 170: /* Return 1 if A - B would overflow in [MIN,MAX] arithmetic.
! 171: See above for restrictions. */
! 172: #define INT_SUBTRACT_RANGE_OVERFLOW(a, b, min, max) \
! 173: ((b) < 0 \
! 174: ? (max) + (b) < (a) \
! 175: : (a) < (min) + (b))
! 176:
! 177: /* Return 1 if - A would overflow in [MIN,MAX] arithmetic.
! 178: See above for restrictions. */
! 179: #define INT_NEGATE_RANGE_OVERFLOW(a, min, max) \
! 180: ((min) < 0 \
! 181: ? (a) < - (max) \
! 182: : 0 < (a))
! 183:
! 184: /* Return 1 if A * B would overflow in [MIN,MAX] arithmetic.
! 185: See above for restrictions. Avoid && and || as they tickle
! 186: bugs in Sun C 5.11 2010/08/13 and other compilers; see
! 187: <http://lists.gnu.org/archive/html/bug-gnulib/2011-05/msg00401.html>. */
! 188: #define INT_MULTIPLY_RANGE_OVERFLOW(a, b, min, max) \
! 189: ((b) < 0 \
! 190: ? ((a) < 0 \
! 191: ? (a) < (max) / (b) \
! 192: : (b) == -1 \
! 193: ? 0 \
! 194: : (min) / (b) < (a)) \
! 195: : (b) == 0 \
! 196: ? 0 \
! 197: : ((a) < 0 \
! 198: ? (a) < (min) / (b) \
! 199: : (max) / (b) < (a)))
! 200:
! 201: /* Return 1 if A / B would overflow in [MIN,MAX] arithmetic.
! 202: See above for restrictions. Do not check for division by zero. */
! 203: #define INT_DIVIDE_RANGE_OVERFLOW(a, b, min, max) \
! 204: ((min) < 0 && (b) == -1 && (a) < - (max))
! 205:
! 206: /* Return 1 if A % B would overflow in [MIN,MAX] arithmetic.
! 207: See above for restrictions. Do not check for division by zero.
! 208: Mathematically, % should never overflow, but on x86-like hosts
! 209: INT_MIN % -1 traps, and the C standard permits this, so treat this
! 210: as an overflow too. */
! 211: #define INT_REMAINDER_RANGE_OVERFLOW(a, b, min, max) \
! 212: INT_DIVIDE_RANGE_OVERFLOW (a, b, min, max)
! 213:
! 214: /* Return 1 if A << B would overflow in [MIN,MAX] arithmetic.
! 215: See above for restrictions. Here, MIN and MAX are for A only, and B need
! 216: not be of the same type as the other arguments. The C standard says that
! 217: behavior is undefined for shifts unless 0 <= B < wordwidth, and that when
! 218: A is negative then A << B has undefined behavior and A >> B has
! 219: implementation-defined behavior, but do not check these other
! 220: restrictions. */
! 221: #define INT_LEFT_SHIFT_RANGE_OVERFLOW(a, b, min, max) \
! 222: ((a) < 0 \
! 223: ? (a) < (min) >> (b) \
! 224: : (max) >> (b) < (a))
! 225:
! 226:
! 227: /* The _GL*_OVERFLOW macros have the same restrictions as the
! 228: *_RANGE_OVERFLOW macros, except that they do not assume that operands
! 229: (e.g., A and B) have the same type as MIN and MAX. Instead, they assume
! 230: that the result (e.g., A + B) has that type. */
! 231: #define _GL_ADD_OVERFLOW(a, b, min, max) \
! 232: ((min) < 0 ? INT_ADD_RANGE_OVERFLOW (a, b, min, max) \
! 233: : (a) < 0 ? (b) <= (a) + (b) \
! 234: : (b) < 0 ? (a) <= (a) + (b) \
! 235: : (a) + (b) < (b))
! 236: #define _GL_SUBTRACT_OVERFLOW(a, b, min, max) \
! 237: ((min) < 0 ? INT_SUBTRACT_RANGE_OVERFLOW (a, b, min, max) \
! 238: : (a) < 0 ? 1 \
! 239: : (b) < 0 ? (a) - (b) <= (a) \
! 240: : (a) < (b))
! 241: #define _GL_MULTIPLY_OVERFLOW(a, b, min, max) \
! 242: (((min) == 0 && (((a) < 0 && 0 < (b)) || ((b) < 0 && 0 < (a)))) \
! 243: || INT_MULTIPLY_RANGE_OVERFLOW (a, b, min, max))
! 244: #define _GL_DIVIDE_OVERFLOW(a, b, min, max) \
! 245: ((min) < 0 ? (b) == _GL_INT_NEGATE_CONVERT (min, 1) && (a) < - (max) \
! 246: : (a) < 0 ? (b) <= (a) + (b) - 1 \
! 247: : (b) < 0 && (a) + (b) <= (a))
! 248: #define _GL_REMAINDER_OVERFLOW(a, b, min, max) \
! 249: ((min) < 0 ? (b) == _GL_INT_NEGATE_CONVERT (min, 1) && (a) < - (max) \
! 250: : (a) < 0 ? (a) % (b) != ((max) - (b) + 1) % (b) \
! 251: : (b) < 0 && ! _GL_UNSIGNED_NEG_MULTIPLE (a, b, max))
! 252:
! 253: /* Return a nonzero value if A is a mathematical multiple of B, where
! 254: A is unsigned, B is negative, and MAX is the maximum value of A's
! 255: type. A's type must be the same as (A % B)'s type. Normally (A %
! 256: -B == 0) suffices, but things get tricky if -B would overflow. */
! 257: #define _GL_UNSIGNED_NEG_MULTIPLE(a, b, max) \
! 258: (((b) < -_GL_SIGNED_INT_MAXIMUM (b) \
! 259: ? (_GL_SIGNED_INT_MAXIMUM (b) == (max) \
! 260: ? (a) \
! 261: : (a) % (_GL_INT_CONVERT (a, _GL_SIGNED_INT_MAXIMUM (b)) + 1)) \
! 262: : (a) % - (b)) \
! 263: == 0)
! 264:
! 265:
! 266: /* Integer overflow checks.
! 267:
! 268: The INT_<op>_OVERFLOW macros return 1 if the corresponding C operators
! 269: might not yield numerically correct answers due to arithmetic overflow.
! 270: They work correctly on all known practical hosts, and do not rely
! 271: on undefined behavior due to signed arithmetic overflow.
! 272:
! 273: Example usage:
! 274:
! 275: long int i = ...;
! 276: long int j = ...;
! 277: if (INT_MULTIPLY_OVERFLOW (i, j))
! 278: printf ("multiply would overflow");
! 279: else
! 280: printf ("product is %ld", i * j);
! 281:
! 282: These macros do not check for all possible numerical problems or
! 283: undefined or unspecified behavior: they do not check for division
! 284: by zero, for bad shift counts, or for shifting negative numbers.
! 285:
! 286: These macros may evaluate their arguments zero or multiple times, so the
! 287: arguments should not have side effects.
! 288:
! 289: These macros are tuned for their last argument being a constant.
! 290:
! 291: Return 1 if the integer expressions A * B, A - B, -A, A * B, A / B,
! 292: A % B, and A << B would overflow, respectively. */
! 293:
! 294: #define INT_ADD_OVERFLOW(a, b) \
! 295: _GL_BINARY_OP_OVERFLOW (a, b, _GL_ADD_OVERFLOW)
! 296: #define INT_SUBTRACT_OVERFLOW(a, b) \
! 297: _GL_BINARY_OP_OVERFLOW (a, b, _GL_SUBTRACT_OVERFLOW)
! 298: #define INT_NEGATE_OVERFLOW(a) \
! 299: INT_NEGATE_RANGE_OVERFLOW (a, _GL_INT_MINIMUM (a), _GL_INT_MAXIMUM (a))
! 300: #define INT_MULTIPLY_OVERFLOW(a, b) \
! 301: _GL_BINARY_OP_OVERFLOW (a, b, _GL_MULTIPLY_OVERFLOW)
! 302: #define INT_DIVIDE_OVERFLOW(a, b) \
! 303: _GL_BINARY_OP_OVERFLOW (a, b, _GL_DIVIDE_OVERFLOW)
! 304: #define INT_REMAINDER_OVERFLOW(a, b) \
! 305: _GL_BINARY_OP_OVERFLOW (a, b, _GL_REMAINDER_OVERFLOW)
! 306: #define INT_LEFT_SHIFT_OVERFLOW(a, b) \
! 307: INT_LEFT_SHIFT_RANGE_OVERFLOW (a, b, \
! 308: _GL_INT_MINIMUM (a), _GL_INT_MAXIMUM (a))
! 309:
! 310: /* Return 1 if the expression A <op> B would overflow,
! 311: where OP_RESULT_OVERFLOW (A, B, MIN, MAX) does the actual test,
! 312: assuming MIN and MAX are the minimum and maximum for the result type.
! 313: Arguments should be free of side effects. */
! 314: #define _GL_BINARY_OP_OVERFLOW(a, b, op_result_overflow) \
! 315: op_result_overflow (a, b, \
! 316: _GL_INT_MINIMUM (0 * (b) + (a)), \
! 317: _GL_INT_MAXIMUM (0 * (b) + (a)))
! 318:
! 319: #endif /* _GL_INTPROPS_H */
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