1 #ifndef INT128_H 2 #define INT128_H 3 4 5 typedef struct Int128 Int128; 6 7 struct Int128 { 8 uint64_t lo; 9 int64_t hi; 10 }; 11 12 static inline Int128 int128_make64(uint64_t a) 13 { 14 return (Int128) { a, 0 }; 15 } 16 17 static inline uint64_t int128_get64(Int128 a) 18 { 19 assert(!a.hi); 20 return a.lo; 21 } 22 23 static inline Int128 int128_zero(void) 24 { 25 return int128_make64(0); 26 } 27 28 static inline Int128 int128_one(void) 29 { 30 return int128_make64(1); 31 } 32 33 static inline Int128 int128_2_64(void) 34 { 35 return (Int128) { 0, 1 }; 36 } 37 38 static inline Int128 int128_exts64(int64_t a) 39 { 40 return (Int128) { .lo = a, .hi = (a < 0) ? -1 : 0 }; 41 } 42 43 static inline Int128 int128_and(Int128 a, Int128 b) 44 { 45 return (Int128) { a.lo & b.lo, a.hi & b.hi }; 46 } 47 48 static inline Int128 int128_rshift(Int128 a, int n) 49 { 50 int64_t h; 51 if (!n) { 52 return a; 53 } 54 h = a.hi >> (n & 63); 55 if (n >= 64) { 56 return (Int128) { h, h >> 63 }; 57 } else { 58 return (Int128) { (a.lo >> n) | ((uint64_t)a.hi << (64 - n)), h }; 59 } 60 } 61 62 static inline Int128 int128_add(Int128 a, Int128 b) 63 { 64 uint64_t lo = a.lo + b.lo; 65 66 /* a.lo <= a.lo + b.lo < a.lo + k (k is the base, 2^64). Hence, 67 * a.lo + b.lo >= k implies 0 <= lo = a.lo + b.lo - k < a.lo. 68 * Similarly, a.lo + b.lo < k implies a.lo <= lo = a.lo + b.lo < k. 69 * 70 * So the carry is lo < a.lo. 71 */ 72 return (Int128) { lo, (uint64_t)a.hi + b.hi + (lo < a.lo) }; 73 } 74 75 static inline Int128 int128_neg(Int128 a) 76 { 77 uint64_t lo = -a.lo; 78 return (Int128) { lo, ~(uint64_t)a.hi + !lo }; 79 } 80 81 static inline Int128 int128_sub(Int128 a, Int128 b) 82 { 83 return (Int128){ a.lo - b.lo, (uint64_t)a.hi - b.hi - (a.lo < b.lo) }; 84 } 85 86 static inline bool int128_nonneg(Int128 a) 87 { 88 return a.hi >= 0; 89 } 90 91 static inline bool int128_eq(Int128 a, Int128 b) 92 { 93 return a.lo == b.lo && a.hi == b.hi; 94 } 95 96 static inline bool int128_ne(Int128 a, Int128 b) 97 { 98 return !int128_eq(a, b); 99 } 100 101 static inline bool int128_ge(Int128 a, Int128 b) 102 { 103 return a.hi > b.hi || (a.hi == b.hi && a.lo >= b.lo); 104 } 105 106 static inline bool int128_lt(Int128 a, Int128 b) 107 { 108 return !int128_ge(a, b); 109 } 110 111 static inline bool int128_le(Int128 a, Int128 b) 112 { 113 return int128_ge(b, a); 114 } 115 116 static inline bool int128_gt(Int128 a, Int128 b) 117 { 118 return !int128_le(a, b); 119 } 120 121 static inline bool int128_nz(Int128 a) 122 { 123 return a.lo || a.hi; 124 } 125 126 static inline Int128 int128_min(Int128 a, Int128 b) 127 { 128 return int128_le(a, b) ? a : b; 129 } 130 131 static inline Int128 int128_max(Int128 a, Int128 b) 132 { 133 return int128_ge(a, b) ? a : b; 134 } 135 136 static inline void int128_addto(Int128 *a, Int128 b) 137 { 138 *a = int128_add(*a, b); 139 } 140 141 static inline void int128_subfrom(Int128 *a, Int128 b) 142 { 143 *a = int128_sub(*a, b); 144 } 145 146 #endif 147