lib/sat-math.h

   1 /*
   2  * Copyright (c) 2008, 2012, 2019 Nicira, Inc.
   3  *
   4  * Licensed under the Apache License, Version 2.0 (the "License");
   5  * you may not use this file except in compliance with the License.
   6  * You may obtain a copy of the License at:
   7  *
   8  *     http://www.apache.org/licenses/LICENSE-2.0
   9  *
  10  * Unless required by applicable law or agreed to in writing, software
  11  * distributed under the License is distributed on an "AS IS" BASIS,
  12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  13  * See the License for the specific language governing permissions and
  14  * limitations under the License.
  15  */
  16
  17 #ifndef SAT_MATH_H
  18 #define SAT_MATH_H 1
  19
  20 #include <limits.h>
  21 #include "openvswitch/util.h"
  22
  23 #ifndef __has_builtin
  24 #define __has_builtin(x) 0
  25 #endif
  26
  27 /* Returns x + y, clamping out-of-range results into the range of the return
  28  * type. */
  29 static inline unsigned int
  30 sat_add(unsigned int x, unsigned int y)
  31 {
  32     return x + y >= x ? x + y : UINT_MAX;
  33 }
  34 static inline long long int
  35 llsat_add__(long long int x, long long int y)
  36 {
  37     return (x >= 0 && y >= 0 && x > LLONG_MAX - y ? LLONG_MAX
  38             : x < 0 && y < 0 && x < LLONG_MIN - y ? LLONG_MIN
  39             : x + y);
  40 }
  41 static inline long long int
  42 llsat_add(long long int x, long long int y)
  43 {
  44 #if (__GNUC__ >= 5 || __has_builtin(__builtin_saddll_overflow)) && !__CHECKER__
  45     long long int sum;
  46     return (!__builtin_saddll_overflow(x, y, &sum) ? sum
  47             : x > 0 ? LLONG_MAX : LLONG_MIN);
  48 #else
  49     return llsat_add__(x, y);
  50 #endif
  51 }
  52
  53 /* Returns x - y, clamping out-of-range results into the range of the return
  54  * type. */
  55 static inline unsigned int
  56 sat_sub(unsigned int x, unsigned int y)
  57 {
  58     return x >= y ? x - y : 0;
  59 }
  60 static inline long long int
  61 llsat_sub__(long long int x, long long int y)
  62 {
  63     return (x >= 0 && y < 0 && x > LLONG_MAX + y ? LLONG_MAX
  64             : x < 0 && y >= 0 && x < LLONG_MIN + y ? LLONG_MIN
  65             : x - y);
  66 }
  67 static inline long long int
  68 llsat_sub(long long int x, long long int y)
  69 {
  70 #if (__GNUC__ >= 5 || __has_builtin(__builtin_ssubll_overflow)) && !__CHECKER__
  71     long long int difference;
  72     return (!__builtin_ssubll_overflow(x, y, &difference) ? difference
  73             : x >= 0 ? LLONG_MAX : LLONG_MIN);
  74 #else
  75     return llsat_sub__(x, y);
  76 #endif
  77 }
  78
  79 /* Returns x * y, clamping out-of-range results into the range of the return
  80  * type. */
  81 static inline unsigned int
  82 sat_mul(unsigned int x, unsigned int y)
  83 {
  84     return OVS_SAT_MUL(x, y);
  85 }
  86 static inline long long int
  87 llsat_mul__(long long int x, long long int y)
  88 {
  89     return (  x > 0 && y > 0 && x > LLONG_MAX / y ? LLONG_MAX
  90             : x < 0 && y > 0 && x < LLONG_MIN / y ? LLONG_MIN
  91             : x > 0 && y < 0 && y < LLONG_MIN / x ? LLONG_MIN
  92             /* Special case because -LLONG_MIN / -1 overflows: */
  93             : x == LLONG_MIN && y == -1 ? LLONG_MAX
  94             : x < 0 && y < 0 && x < LLONG_MAX / y ? LLONG_MAX
  95             : x * y);
  96 }
  97 static inline long long int
  98 llsat_mul(long long int x, long long int y)
  99 {
 100 #if (__GNUC__ >= 5 || __has_builtin(__builtin_smulll_overflow)) && !__CHECKER__
 101     long long int product;
 102     return (!__builtin_smulll_overflow(x, y, &product) ? product
 103             : (x > 0) == (y > 0) ? LLONG_MAX : LLONG_MIN);
 104 #else
 105     return llsat_mul__(x, y);
 106 #endif
 107 }
 108
 109 #endif /* sat-math.h */