New upstream version 1.8

[debian/gzip] / lib / intprops.h

diff --git a/lib/intprops.h b/lib/intprops.h
index f57f9b4ddab25cf228f3c736e05cda6a6690c86d..31521395e2a65e2bde2f6e1303081591d46bdb15 100644 (file)
--- a/lib/intprops.h
+++ b/lib/intprops.h
@@ -1,10 +1,10 @@
 /* intprops.h -- properties of integer types
 
 /* intprops.h -- properties of integer types
 

-   Copyright (C) 2001-2005, 2009-2013 Free Software Foundation, Inc.
+   Copyright (C) 2001-2016 Free Software Foundation, Inc.

 
 

-   This program is free software: you can redistribute it and/or modify
-   it under the terms of the GNU General Public License as published by
-   the Free Software Foundation; either version 3 of the License, or
+   This program is free software: you can redistribute it and/or modify it
+   under the terms of the GNU General Public License as published
+   by the Free Software Foundation; either version 3 of the License, or

    (at your option) any later version.
 
    This program is distributed in the hope that it will be useful,
    (at your option) any later version.
 
    This program is distributed in the hope that it will be useful,


@@ -21,9 +21,9 @@
 #define _GL_INTPROPS_H
 
 #include <limits.h>
 #define _GL_INTPROPS_H
 
 #include <limits.h>

+#include <verify.h>

 
 

-/* Return an integer value, converted to the same type as the integer
-   expression E after integer type promotion.  V is the unconverted value.  */
+/* Return a value with the common real type of E and V and the value of V.  */

 #define _GL_INT_CONVERT(e, v) (0 * (e) + (v))
 
 /* Act like _GL_INT_CONVERT (E, -V) but work around a bug in IRIX 6.5 cc; see
 #define _GL_INT_CONVERT(e, v) (0 * (e) + (v))
 
 /* Act like _GL_INT_CONVERT (E, -V) but work around a bug in IRIX 6.5 cc; see


@@ -37,37 +37,18 @@
    an integer.  */
 #define TYPE_IS_INTEGER(t) ((t) 1.5 == 1)
 
    an integer.  */
 #define TYPE_IS_INTEGER(t) ((t) 1.5 == 1)
 

-/* True if negative values of the signed integer type T use two's
-   complement, ones' complement, or signed magnitude representation,
-   respectively.  Much GNU code assumes two's complement, but some
-   people like to be portable to all possible C hosts.  */
-#define TYPE_TWOS_COMPLEMENT(t) ((t) ~ (t) 0 == (t) -1)
-#define TYPE_ONES_COMPLEMENT(t) ((t) ~ (t) 0 == 0)
-#define TYPE_SIGNED_MAGNITUDE(t) ((t) ~ (t) 0 < (t) -1)
-
-/* True if the signed integer expression E uses two's complement.  */
-#define _GL_INT_TWOS_COMPLEMENT(e) (~ _GL_INT_CONVERT (e, 0) == -1)
-
-/* True if the arithmetic type T is signed.  */
+/* True if the real type T is signed.  */

 #define TYPE_SIGNED(t) (! ((t) 0 < (t) -1))
 
 #define TYPE_SIGNED(t) (! ((t) 0 < (t) -1))
 

-/* Return 1 if the integer expression E, after integer promotion, has
-   a signed type.  */
-#define _GL_INT_SIGNED(e) (_GL_INT_NEGATE_CONVERT (e, 1) < 0)
+/* Return 1 if the real expression E, after promotion, has a
+   signed or floating type.  */
+#define EXPR_SIGNED(e) (_GL_INT_NEGATE_CONVERT (e, 1) < 0)

 
 
 
 

-/* Minimum and maximum values for integer types and expressions.  These
-   macros have undefined behavior if T is signed and has padding bits.
-   If this is a problem for you, please let us know how to fix it for
-   your host.  */
+/* Minimum and maximum values for integer types and expressions.  */

 
 /* The maximum and minimum values for the integer type T.  */
 
 /* The maximum and minimum values for the integer type T.  */

-#define TYPE_MINIMUM(t)                                                 \
-  ((t) (! TYPE_SIGNED (t)                                               \
-        ? (t) 0                                                         \
-        : TYPE_SIGNED_MAGNITUDE (t)                                     \
-        ? ~ (t) 0                                                       \
-        : ~ TYPE_MAXIMUM (t)))
+#define TYPE_MINIMUM(t) ((t) ~ TYPE_MAXIMUM (t))

 #define TYPE_MAXIMUM(t)                                                 \
   ((t) (! TYPE_SIGNED (t)                                               \
         ? (t) -1                                                        \
 #define TYPE_MAXIMUM(t)                                                 \
   ((t) (! TYPE_SIGNED (t)                                               \
         ? (t) -1                                                        \


@@ -76,20 +57,38 @@
 /* The maximum and minimum values for the type of the expression E,
    after integer promotion.  E should not have side effects.  */
 #define _GL_INT_MINIMUM(e)                                              \
 /* The maximum and minimum values for the type of the expression E,
    after integer promotion.  E should not have side effects.  */
 #define _GL_INT_MINIMUM(e)                                              \

-  (_GL_INT_SIGNED (e)                                                   \
-   ? - _GL_INT_TWOS_COMPLEMENT (e) - _GL_SIGNED_INT_MAXIMUM (e)         \
+  (EXPR_SIGNED (e)                                                      \
+   ? ~ _GL_SIGNED_INT_MAXIMUM (e)                                       \

    : _GL_INT_CONVERT (e, 0))
 #define _GL_INT_MAXIMUM(e)                                              \
    : _GL_INT_CONVERT (e, 0))
 #define _GL_INT_MAXIMUM(e)                                              \

-  (_GL_INT_SIGNED (e)                                                   \
+  (EXPR_SIGNED (e)                                                      \

    ? _GL_SIGNED_INT_MAXIMUM (e)                                         \
    : _GL_INT_NEGATE_CONVERT (e, 1))
 #define _GL_SIGNED_INT_MAXIMUM(e)                                       \
   (((_GL_INT_CONVERT (e, 1) << (sizeof ((e) + 0) * CHAR_BIT - 2)) - 1) * 2 + 1)
 
    ? _GL_SIGNED_INT_MAXIMUM (e)                                         \
    : _GL_INT_NEGATE_CONVERT (e, 1))
 #define _GL_SIGNED_INT_MAXIMUM(e)                                       \
   (((_GL_INT_CONVERT (e, 1) << (sizeof ((e) + 0) * CHAR_BIT - 2)) - 1) * 2 + 1)
 

+/* This include file assumes that signed types are two's complement without
+   padding bits; the above macros have undefined behavior otherwise.
+   If this is a problem for you, please let us know how to fix it for your host.
+   As a sanity check, test the assumption for some signed types that
+   <limits.h> bounds.  */
+verify (TYPE_MINIMUM (signed char) == SCHAR_MIN);
+verify (TYPE_MAXIMUM (signed char) == SCHAR_MAX);
+verify (TYPE_MINIMUM (short int) == SHRT_MIN);
+verify (TYPE_MAXIMUM (short int) == SHRT_MAX);
+verify (TYPE_MINIMUM (int) == INT_MIN);
+verify (TYPE_MAXIMUM (int) == INT_MAX);
+verify (TYPE_MINIMUM (long int) == LONG_MIN);
+verify (TYPE_MAXIMUM (long int) == LONG_MAX);
+#ifdef LLONG_MAX
+verify (TYPE_MINIMUM (long long int) == LLONG_MIN);
+verify (TYPE_MAXIMUM (long long int) == LLONG_MAX);
+#endif

 
 

-/* Return 1 if the __typeof__ keyword works.  This could be done by
+/* Does the __typeof__ keyword work?  This could be done by

    'configure', but for now it's easier to do it by hand.  */
    'configure', but for now it's easier to do it by hand.  */

-#if 2 <= __GNUC__ || defined __IBM__TYPEOF__ || 0x5110 <= __SUNPRO_C
+#if (2 <= __GNUC__ || defined __IBM__TYPEOF__ \
+     || (0x5110 <= __SUNPRO_C && !__STDC__))

 # define _GL_HAVE___TYPEOF__ 1
 #else
 # define _GL_HAVE___TYPEOF__ 0
 # define _GL_HAVE___TYPEOF__ 1
 #else
 # define _GL_HAVE___TYPEOF__ 0


@@ -262,22 +261,29 @@
     : (a) % - (b))                                                      \
    == 0)
 
     : (a) % - (b))                                                      \
    == 0)
 

-
-/* Integer overflow checks.
+/* Check for integer overflow, and report low order bits of answer.

 
    The INT_<op>_OVERFLOW macros return 1 if the corresponding C operators
    might not yield numerically correct answers due to arithmetic overflow.
 
    The INT_<op>_OVERFLOW macros return 1 if the corresponding C operators
    might not yield numerically correct answers due to arithmetic overflow.

-   They work correctly on all known practical hosts, and do not rely
+   The INT_<op>_WRAPV macros also store the low-order bits of the answer.
+   These macros work correctly on all known practical hosts, and do not rely

    on undefined behavior due to signed arithmetic overflow.
 
    on undefined behavior due to signed arithmetic overflow.
 

-   Example usage:
+   Example usage, assuming A and B are long int:

 
 

-     long int i = ...;
-     long int j = ...;
-     if (INT_MULTIPLY_OVERFLOW (i, j))
-       printf ("multiply would overflow");
+     if (INT_MULTIPLY_OVERFLOW (a, b))
+       printf ("result would overflow\n");

      else
      else

-       printf ("product is %ld", i * j);
+       printf ("result is %ld (no overflow)\n", a * b);
+
+   Example usage with WRAPV flavor:
+
+     long int result;
+     bool overflow = INT_MULTIPLY_WRAPV (a, b, &result);
+     printf ("result is %ld (%s)\n", result,
+             overflow ? "after overflow" : "no overflow");
+
+   Restrictions on these macros:

 
    These macros do not check for all possible numerical problems or
    undefined or unspecified behavior: they do not check for division
 
    These macros do not check for all possible numerical problems or
    undefined or unspecified behavior: they do not check for division


@@ -286,6 +292,9 @@
    These macros may evaluate their arguments zero or multiple times, so the
    arguments should not have side effects.
 
    These macros may evaluate their arguments zero or multiple times, so the
    arguments should not have side effects.
 

+   The WRAPV macros are not constant expressions.  They support only
+   +, binary -, and *.  The result type must be signed.
+

    These macros are tuned for their last argument being a constant.
 
    Return 1 if the integer expressions A * B, A - B, -A, A * B, A / B,
    These macros are tuned for their last argument being a constant.
 
    Return 1 if the integer expressions A * B, A - B, -A, A * B, A / B,


@@ -316,4 +325,104 @@
                       _GL_INT_MINIMUM (0 * (b) + (a)),          \
                       _GL_INT_MAXIMUM (0 * (b) + (a)))
 
                       _GL_INT_MINIMUM (0 * (b) + (a)),          \
                       _GL_INT_MAXIMUM (0 * (b) + (a)))
 

+/* Compute A + B, A - B, A * B, respectively, storing the result into *R.
+   Return 1 if the result overflows.  See above for restrictions.  */
+#define INT_ADD_WRAPV(a, b, r) \
+  _GL_INT_OP_WRAPV (a, b, r, +, __builtin_add_overflow, INT_ADD_OVERFLOW)
+#define INT_SUBTRACT_WRAPV(a, b, r) \
+  _GL_INT_OP_WRAPV (a, b, r, -, __builtin_sub_overflow, INT_SUBTRACT_OVERFLOW)
+#define INT_MULTIPLY_WRAPV(a, b, r) \
+  _GL_INT_OP_WRAPV (a, b, r, *, __builtin_mul_overflow, INT_MULTIPLY_OVERFLOW)
+
+#ifndef __has_builtin
+# define __has_builtin(x) 0
+#endif
+
+/* Nonzero if this compiler has GCC bug 68193 or Clang bug 25390.  See:
+   https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68193
+   https://llvm.org/bugs/show_bug.cgi?id=25390
+   For now, assume all versions of GCC-like compilers generate bogus
+   warnings for _Generic.  This matters only for older compilers that
+   lack __builtin_add_overflow.  */
+#if __GNUC__
+# define _GL__GENERIC_BOGUS 1
+#else
+# define _GL__GENERIC_BOGUS 0
+#endif
+
+/* Store A <op> B into *R, where OP specifies the operation.
+   BUILTIN is the builtin operation, and OVERFLOW the overflow predicate.
+   See above for restrictions.  */
+#if 5 <= __GNUC__ || __has_builtin (__builtin_add_overflow)
+# define _GL_INT_OP_WRAPV(a, b, r, op, builtin, overflow) builtin (a, b, r)
+#elif 201112 <= __STDC_VERSION__ && !_GL__GENERIC_BOGUS
+# define _GL_INT_OP_WRAPV(a, b, r, op, builtin, overflow) \
+   (_Generic \
+    (*(r), \
+     signed char: \
+       _GL_INT_OP_CALC (a, b, r, op, overflow, unsigned char, \
+                        signed char, SCHAR_MIN, SCHAR_MAX), \
+     short int: \
+       _GL_INT_OP_CALC (a, b, r, op, overflow, unsigned short int, \
+                        short int, SHRT_MIN, SHRT_MAX), \
+     int: \
+       _GL_INT_OP_CALC (a, b, r, op, overflow, unsigned int, \
+                        int, INT_MIN, INT_MAX), \
+     long int: \
+       _GL_INT_OP_CALC (a, b, r, op, overflow, unsigned long int, \
+                        long int, LONG_MIN, LONG_MAX), \
+     long long int: \
+       _GL_INT_OP_CALC (a, b, r, op, overflow, unsigned long long int, \
+                        long long int, LLONG_MIN, LLONG_MAX)))
+#else
+# define _GL_INT_OP_WRAPV(a, b, r, op, builtin, overflow) \
+   (sizeof *(r) == sizeof (signed char) \
+    ? _GL_INT_OP_CALC (a, b, r, op, overflow, unsigned char, \
+                       signed char, SCHAR_MIN, SCHAR_MAX) \
+    : sizeof *(r) == sizeof (short int) \
+    ? _GL_INT_OP_CALC (a, b, r, op, overflow, unsigned short int, \
+                       short int, SHRT_MIN, SHRT_MAX) \
+    : sizeof *(r) == sizeof (int) \
+    ? _GL_INT_OP_CALC (a, b, r, op, overflow, unsigned int, \
+                       int, INT_MIN, INT_MAX) \
+    : _GL_INT_OP_WRAPV_LONGISH(a, b, r, op, overflow))
+# ifdef LLONG_MAX
+#  define _GL_INT_OP_WRAPV_LONGISH(a, b, r, op, overflow) \
+    (sizeof *(r) == sizeof (long int) \
+     ? _GL_INT_OP_CALC (a, b, r, op, overflow, unsigned long int, \
+                        long int, LONG_MIN, LONG_MAX) \
+     : _GL_INT_OP_CALC (a, b, r, op, overflow, unsigned long long int, \
+                        long long int, LLONG_MIN, LLONG_MAX))
+# else
+#  define _GL_INT_OP_WRAPV_LONGISH(a, b, r, op, overflow) \
+    _GL_INT_OP_CALC (a, b, r, op, overflow, unsigned long int, \
+                     long int, LONG_MIN, LONG_MAX))
+# endif
+#endif
+
+/* Store the low-order bits of A <op> B into *R, where the operation
+   is given by OP.  Use the unsigned type UT for calculation to avoid
+   overflow problems.  *R's type is T, with extremal values TMIN and
+   TMAX.  T must be a signed integer type.  */
+#define _GL_INT_OP_CALC(a, b, r, op, overflow, ut, t, tmin, tmax) \
+  (sizeof ((a) op (b)) < sizeof (t) \
+   ? _GL_INT_OP_CALC1 ((t) (a), (t) (b), r, op, overflow, ut, t, tmin, tmax) \
+   : _GL_INT_OP_CALC1 (a, b, r, op, overflow, ut, t, tmin, tmax))
+#define _GL_INT_OP_CALC1(a, b, r, op, overflow, ut, t, tmin, tmax) \
+  ((overflow (a, b) \
+    || (EXPR_SIGNED ((a) op (b)) && ((a) op (b)) < (tmin)) \
+    || (tmax) < ((a) op (b))) \
+   ? (*(r) = _GL_INT_OP_WRAPV_VIA_UNSIGNED (a, b, op, ut, t, tmin, tmax), 1) \
+   : (*(r) = _GL_INT_OP_WRAPV_VIA_UNSIGNED (a, b, op, ut, t, tmin, tmax), 0))
+
+/* Return A <op> B, where the operation is given by OP.  Use the
+   unsigned type UT for calculation to avoid overflow problems.
+   Convert the result to type T without overflow by subtracting TMIN
+   from large values before converting, and adding it afterwards.
+   Compilers can optimize all the operations except OP.  */
+#define _GL_INT_OP_WRAPV_VIA_UNSIGNED(a, b, op, ut, t, tmin, tmax) \
+  (((ut) (a) op (ut) (b)) <= (tmax) \
+   ? (t) ((ut) (a) op (ut) (b)) \
+   : ((t) (((ut) (a) op (ut) (b)) - (tmin)) + (tmin)))
+

 #endif /* _GL_INTPROPS_H */
 #endif /* _GL_INTPROPS_H */