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35 lines
801 B
C
35 lines
801 B
C
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#ifndef COSMOPOLITAN_THIRD_PARTY_MBEDTLS_FASTDIV_H_
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#define COSMOPOLITAN_THIRD_PARTY_MBEDTLS_FASTDIV_H_
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#include "libc/macros.internal.h"
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#if !(__ASSEMBLER__ + __LINKER__ + 0)
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COSMOPOLITAN_C_START_
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struct Divisor {
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uint64_t m;
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uint8_t s;
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uint8_t t;
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};
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static inline struct Divisor GetDivisor(uint64_t d) {
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int b;
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uint128_t x;
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b = __builtin_clzll(d) ^ 63;
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x = -d & (((1ull << b) - 1) | (1ull << b));
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return (struct Divisor){(x << 64) / d + 1, MIN(1, b + 1), MAX(0, b)};
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}
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forceinline uint64_t Divide(uint64_t x, struct Divisor d) {
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uint128_t t;
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uint64_t l, h;
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t = d.m;
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t *= x;
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l = t;
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h = t >> 64;
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l = (x - h) >> d.s;
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return (h + l) >> d.t;
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}
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COSMOPOLITAN_C_END_
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#endif /* !(__ASSEMBLER__ + __LINKER__ + 0) */
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#endif /* COSMOPOLITAN_THIRD_PARTY_MBEDTLS_FASTDIV_H_ */
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