32 lines
931 B
C
32 lines
931 B
C
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#ifndef COSMOPOLITAN_LIBC_ALG_BISECTCARLEFT_H_
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#define COSMOPOLITAN_LIBC_ALG_BISECTCARLEFT_H_
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#if !(__ASSEMBLER__ + __LINKER__ + 0)
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COSMOPOLITAN_C_START_
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/**
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* Floor binary search of low 32-bits of 64-bit array items.
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*
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* This is well-suited to NexGen-32e, requiring less than 32 bytes of
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* code. It's particularly useful for frozen maps, requiring less effort
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* and memory than a perfect hash table.
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*/
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forceinline int32_t bisectcarleft(const int32_t (*cons)[2], size_t count,
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const int32_t key) {
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size_t left = 0;
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size_t right = count;
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while (left < right) {
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size_t m = (left + right) >> 1;
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if (cons[m][0] < key) {
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left = m + 1;
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} else {
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right = m;
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}
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}
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if (left && (left == count || cons[left][0] > key)) left--;
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return left;
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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_LIBC_ALG_BISECTCARLEFT_H_ */
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