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// SPDX-FileCopyrightText: 2025-2026 Jonathan Busse <jonathan@jbusse.de>

//

// SPDX-License-Identifier: AGPL-3.0-only


#ifndef EPSTEIN_HPDYAD

#define EPSTEIN_HPDYAD


#define HPDYAD_MAX_LIMBS 32


typedef struct {

    signed char sign; // +1 or -1

    unsigned char n;  // number of used limbs (0 => zero)

    int exp2;         // global power of two (negative for dyadic rationals)

    unsigned int limb[HPDYAD_MAX_LIMBS];

} hpdyad_t;


unsigned ctz64(unsigned long long x);


int msb32(unsigned int x);


void hpdyad_set_ull(hpdyad_t *a, unsigned long long x, signed char sign);


void hpdyad_normalize(hpdyad_t *a);


void hpdyad_mul(hpdyad_t *out, const hpdyad_t *a, const hpdyad_t *b);


void hpdyad_shr_bits_sticky(hpdyad_t *dst, const hpdyad_t *src, unsigned int bits);


void hpdyad_shl_bits(hpdyad_t *dst, const hpdyad_t *src, int bits);


void hpdyad_add(hpdyad_t *out, const hpdyad_t *a, const hpdyad_t *b);


double hpdyad_to_double(const hpdyad_t *a);


#endif

ctz64
unsigned ctz64(unsigned long long x)
Count trailing zero bits in a 64-bit unsigned integer.
Definition hpdyad.c:17

hpdyad_set_ull
void hpdyad_set_ull(hpdyad_t *a, unsigned long long x, signed char sign)
Initialize hpdyad from unsigned long long with sign.
Definition hpdyad.c:65

msb32
int msb32(unsigned int x)
Find index of most significant bit in a 32-bit unsigned integer.
Definition hpdyad.c:33

hpdyad_mul
void hpdyad_mul(hpdyad_t *out, const hpdyad_t *a, const hpdyad_t *b)
Multiply two high precision dyadic numbers (hpdyad's): out = a * b.
Definition hpdyad.c:162

hpdyad_add
void hpdyad_add(hpdyad_t *out, const hpdyad_t *a, const hpdyad_t *b)
Add two high precision dyadic numbers (hpdyad's): out = a + b.
Definition hpdyad.c:512

HPDYAD_MAX_LIMBS
#define HPDYAD_MAX_LIMBS
Maximum number of 32-bit limbs in fixed-size representation (1024 bits total).
Definition hpdyad.h:16

hpdyad_to_double
double hpdyad_to_double(const hpdyad_t *a)
Convert hpdyad to double with round-to-nearest-even.
Definition hpdyad.c:614

hpdyad_normalize
void hpdyad_normalize(hpdyad_t *a)
Normalize hpdyad: trim leading zeros and left-shift mantissa so MSB of top limb is 1.
Definition hpdyad.c:94

hpdyad_shr_bits_sticky
void hpdyad_shr_bits_sticky(hpdyad_t *dst, const hpdyad_t *src, unsigned int bits)
Right-shift mantissa with sticky bit (value-preserving)
Definition hpdyad.c:240

hpdyad_shl_bits
void hpdyad_shl_bits(hpdyad_t *dst, const hpdyad_t *src, int bits)
Left-shift mantissa by specified number of bits (value-preserving)
Definition hpdyad.c:446

hpdyad_t
Fixed-size high-precision dyadic number (hpdyad) with separate sign and binary exponent.
Definition hpdyad.h:28