variant2_int_sqrt.h File Reference

#include <math.h>
#include <float.h>

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Macros
#define	VARIANT2_INTEGER_MATH_SQRT_STEP_SSE2()
#define	VARIANT2_INTEGER_MATH_SQRT_STEP_FP64()
#define	VARIANT2_INTEGER_MATH_SQRT_STEP_REF()
#define	VARIANT2_INTEGER_MATH_SQRT_FIXUP(r)

Functions
static uint32_t	integer_square_root_v2 (uint64_t n)

Macro Definition Documentation

VARIANT2_INTEGER_MATH_SQRT_FIXUP

#define VARIANT2_INTEGER_MATH_SQRT_FIXUP

(

r

)

Value:

do { \
  const uint64_t s = r >> 1; \
  const uint64_t b = r & 1; \
  const uint64_t r2 = (uint64_t)(s) * (s + b) + (r << 32); \
  r += ((r2 + b > sqrt_input) ? -1 : 0) + ((r2 + (1ULL << 32) < sqrt_input - s) ? 1 : 0); \
} while(0)

VARIANT2_INTEGER_MATH_SQRT_STEP_FP64

#define VARIANT2_INTEGER_MATH_SQRT_STEP_FP64

(

)

Value:

do { \
  sqrt_result = sqrt(sqrt_input + 18446744073709551616.0) * 2.0 - 8589934592.0; \
} while(0)

VARIANT2_INTEGER_MATH_SQRT_STEP_REF

#define VARIANT2_INTEGER_MATH_SQRT_STEP_REF

(

)

Value:

sqrt_result = integer_square_root_v2(sqrt_input)

VARIANT2_INTEGER_MATH_SQRT_STEP_SSE2

#define VARIANT2_INTEGER_MATH_SQRT_STEP_SSE2

(

)

Value:

do { \
  const __m128i exp_double_bias = _mm_set_epi64x(0, 1023ULL << 52); \
  __m128d x = _mm_castsi128_pd(_mm_add_epi64(_mm_cvtsi64_si128(sqrt_input >> 12), exp_double_bias)); \
  x = _mm_sqrt_sd(_mm_setzero_pd(), x); \
  sqrt_result = (uint64_t)(_mm_cvtsi128_si64(_mm_sub_epi64(_mm_castpd_si128(x), exp_double_bias))) >> 19; \
} while(0)

Function Documentation

integer_square_root_v2()

uint32_t integer_square_root_v2 ( uint64_t n )

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