mirror of https://github.com/neovim/neovim.git
77 lines
1.4 KiB
C
77 lines
1.4 KiB
C
// uncrustify:off
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#include <math.h>
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// uncrustify:on
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#include <stdint.h>
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#include <string.h>
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#ifdef _MSC_VER
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# include <intrin.h> // Required for _BitScanForward64
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#endif
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#include "nvim/math.h"
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#ifdef INCLUDE_GENERATED_DECLARATIONS
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# include "math.c.generated.h"
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#endif
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int xfpclassify(double d)
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FUNC_ATTR_CONST
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{
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uint64_t m;
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memcpy(&m, &d, sizeof(m));
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int e = 0x7ff & (m >> 52);
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m = 0xfffffffffffffULL & m;
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switch (e) {
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default:
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return FP_NORMAL;
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case 0x000:
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return m ? FP_SUBNORMAL : FP_ZERO;
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case 0x7ff:
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return m ? FP_NAN : FP_INFINITE;
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}
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}
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int xisinf(double d)
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FUNC_ATTR_CONST
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{
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return FP_INFINITE == xfpclassify(d);
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}
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int xisnan(double d)
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FUNC_ATTR_CONST
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{
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return FP_NAN == xfpclassify(d);
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}
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/// Count trailing zeroes at the end of bit field.
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int xctz(uint64_t x)
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{
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// If x == 0, that means all bits are zeroes.
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if (x == 0) {
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return 8 * sizeof(x);
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}
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// Use compiler builtin if possible.
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#if defined(__clang__) || (defined(__GNUC__) && (__GNUC__ >= 4))
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return __builtin_ctzll(x);
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#elif defined(HAVE_BITSCANFORWARD64)
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unsigned long index;
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_BitScanForward64(&index, x);
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return (int)index;
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#else
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int count = 0;
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// Set x's trailing zeroes to ones and zero the rest.
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x = (x ^ (x - 1)) >> 1;
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// Increment count until there are just zero bits remaining.
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while (x) {
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count++;
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x >>= 1;
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}
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return count;
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#endif
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}
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