147 lines
2.7 KiB
C
147 lines
2.7 KiB
C
#ifndef INT128_H
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#define INT128_H
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typedef struct Int128 Int128;
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struct Int128 {
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uint64_t lo;
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int64_t hi;
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};
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static inline Int128 int128_make64(uint64_t a)
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{
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return (Int128) { a, 0 };
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}
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static inline uint64_t int128_get64(Int128 a)
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{
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assert(!a.hi);
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return a.lo;
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}
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static inline Int128 int128_zero(void)
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{
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return int128_make64(0);
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}
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static inline Int128 int128_one(void)
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{
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return int128_make64(1);
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}
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static inline Int128 int128_2_64(void)
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{
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return (Int128) { 0, 1 };
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}
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static inline Int128 int128_exts64(int64_t a)
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{
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return (Int128) { .lo = a, .hi = (a < 0) ? -1 : 0 };
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}
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static inline Int128 int128_and(Int128 a, Int128 b)
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{
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return (Int128) { a.lo & b.lo, a.hi & b.hi };
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}
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static inline Int128 int128_rshift(Int128 a, int n)
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{
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int64_t h;
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if (!n) {
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return a;
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}
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h = a.hi >> (n & 63);
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if (n >= 64) {
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return (Int128) { h, h >> 63 };
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} else {
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return (Int128) { (a.lo >> n) | ((uint64_t)a.hi << (64 - n)), h };
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}
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}
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static inline Int128 int128_add(Int128 a, Int128 b)
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{
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uint64_t lo = a.lo + b.lo;
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/* a.lo <= a.lo + b.lo < a.lo + k (k is the base, 2^64). Hence,
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* a.lo + b.lo >= k implies 0 <= lo = a.lo + b.lo - k < a.lo.
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* Similarly, a.lo + b.lo < k implies a.lo <= lo = a.lo + b.lo < k.
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*
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* So the carry is lo < a.lo.
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*/
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return (Int128) { lo, (uint64_t)a.hi + b.hi + (lo < a.lo) };
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}
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static inline Int128 int128_neg(Int128 a)
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{
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uint64_t lo = -a.lo;
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return (Int128) { lo, ~(uint64_t)a.hi + !lo };
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}
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static inline Int128 int128_sub(Int128 a, Int128 b)
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{
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return (Int128){ a.lo - b.lo, (uint64_t)a.hi - b.hi - (a.lo < b.lo) };
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}
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static inline bool int128_nonneg(Int128 a)
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{
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return a.hi >= 0;
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}
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static inline bool int128_eq(Int128 a, Int128 b)
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{
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return a.lo == b.lo && a.hi == b.hi;
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}
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static inline bool int128_ne(Int128 a, Int128 b)
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{
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return !int128_eq(a, b);
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}
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static inline bool int128_ge(Int128 a, Int128 b)
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{
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return a.hi > b.hi || (a.hi == b.hi && a.lo >= b.lo);
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}
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static inline bool int128_lt(Int128 a, Int128 b)
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{
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return !int128_ge(a, b);
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}
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static inline bool int128_le(Int128 a, Int128 b)
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{
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return int128_ge(b, a);
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}
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static inline bool int128_gt(Int128 a, Int128 b)
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{
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return !int128_le(a, b);
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}
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static inline bool int128_nz(Int128 a)
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{
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return a.lo || a.hi;
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}
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static inline Int128 int128_min(Int128 a, Int128 b)
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{
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return int128_le(a, b) ? a : b;
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}
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static inline Int128 int128_max(Int128 a, Int128 b)
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{
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return int128_ge(a, b) ? a : b;
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}
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static inline void int128_addto(Int128 *a, Int128 b)
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{
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*a = int128_add(*a, b);
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}
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static inline void int128_subfrom(Int128 *a, Int128 b)
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{
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*a = int128_sub(*a, b);
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}
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#endif
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