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e8eec22d15
Shifting an integer larger than its bit width can have undefined behavior. This not only fixes that issue, but also optimizes the shift functions.
109 lines
2.5 KiB
C
109 lines
2.5 KiB
C
/*
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* Copyright (c) 2015 Hugh Bailey <obs.jim@gmail.com>
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*
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* Permission to use, copy, modify, and distribute this software for any
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* purpose with or without fee is hereby granted, provided that the above
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* copyright notice and this permission notice appear in all copies.
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*
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* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
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* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
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* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
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* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
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* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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*/
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#pragma once
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struct util_uint128 {
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union {
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uint32_t i32[4];
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struct {
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uint64_t low;
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uint64_t high;
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};
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};
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};
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typedef struct util_uint128 util_uint128_t;
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static inline util_uint128_t util_add128(util_uint128_t a, util_uint128_t b)
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{
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util_uint128_t out;
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uint64_t val;
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val = (a.low & 0xFFFFFFFFULL) + (b.low & 0xFFFFFFFFULL);
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out.i32[0] = (uint32_t)(val & 0xFFFFFFFFULL);
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val >>= 32;
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val += (a.low >> 32) + (b.low >> 32);
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out.i32[1] = (uint32_t)val;
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val >>= 32;
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val += (a.high & 0xFFFFFFFFULL) + (b.high & 0xFFFFFFFFULL);
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out.i32[2] = (uint32_t)(val & 0xFFFFFFFFULL);
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val >>= 32;
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val += (a.high >> 32) + (b.high >> 32);
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out.i32[3] = (uint32_t)val;
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return out;
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}
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static inline util_uint128_t util_lshift64_internal_32(uint64_t a)
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{
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util_uint128_t val;
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val.low = a << 32;
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val.high = a >> 32;
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return val;
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}
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static inline util_uint128_t util_lshift64_internal_64(uint64_t a)
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{
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util_uint128_t val;
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val.low = 0;
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val.high = a;
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return val;
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}
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static inline util_uint128_t util_mul64_64(uint64_t a, uint64_t b)
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{
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util_uint128_t out;
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uint64_t m;
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m = (a & 0xFFFFFFFFULL) * (b & 0xFFFFFFFFULL);
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out.low = m;
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out.high = 0;
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m = (a >> 32) * (b & 0xFFFFFFFFULL);
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out = util_add128(out, util_lshift64_internal_32(m));
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m = (a & 0xFFFFFFFFULL) * (b >> 32);
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out = util_add128(out, util_lshift64_internal_32(m));
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m = (a >> 32) * (b >> 32);
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out = util_add128(out, util_lshift64_internal_64(m));
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return out;
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}
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static inline util_uint128_t util_div128_32(util_uint128_t a, uint32_t b)
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{
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util_uint128_t out;
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uint64_t val = 0;
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for (int i = 3; i >= 0; i--) {
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val = (val << 32) | a.i32[i];
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if (val < b) {
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out.i32[i] = 0;
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continue;
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}
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out.i32[i] = (uint32_t)(val / b);
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val = val % b;
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}
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return out;
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}
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