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mruby-bigint: always use 32-bit limbs by default

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Remove automatic downgrade to 16-bit limbs on 32-bit Windows.
Modern compilers (including MSVC) have supported uint64_t for decades.
MRB_NO_MPZ64BIT remains available for constrained platforms.

Adjust BATCH_DIVISOR and BATCH_DIGITS for 16-bit limb compatibility:
- 32-bit limbs: 10^9 (9 digits per batch)
- 16-bit limbs: 10^4 (4 digits per batch)

Co-authored-by: Claude <noreply@anthropic.com>
This commit is contained in:
Yukihiro "Matz" Matsumoto
2026-01-14 10:08:05 +09:00
parent 86c6048767
commit c747c77f40
2 changed files with 17 additions and 12 deletions
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mrbgems/mruby-bigint/core/bigint.c
+17 -8
View File
@@ -2545,13 +2545,20 @@ dc_scratch_clear(mpz_ctx_t *ctx, dc_to_s_scratch_t *scratch)
* The caller must ensure num_digits >= actual digits in x.
* Leading zeros are added if x has fewer digits than num_digits.
*/
/* Batch divisor: 10^9 for extracting 9 digits at once */
/* Batch divisor for extracting multiple digits at once */
#ifdef MRB_NO_MPZ64BIT
/* 16-bit limbs: 10^4 fits in 16 bits */
#define BATCH_DIVISOR 10000UL
#define BATCH_DIGITS 4
#else
/* 32-bit limbs: 10^9 fits in 32 bits */
#define BATCH_DIVISOR 1000000000UL
#define BATCH_DIGITS 9
#endif
/*
* Divide limb array by 10^9 in place, returning remainder.
* Used for extracting 9 decimal digits at a time.
* Divide limb array by BATCH_DIVISOR in place, returning remainder.
* Used for extracting BATCH_DIGITS decimal digits at a time.
* Compilers optimize constant division to multiplication+shift.
*/
static mp_limb
@@ -2598,18 +2605,20 @@ mpz_get_str_dc_recur(mpz_ctx_t *ctx, char *s, mpz_t *x, size_t num_digits,
mpz_set(ctx, tmp, x);
while (pos > 0 && !zero_p(tmp)) {
/* Divide by 10^9 in place, get remainder as 9 digits */
/* Divide by BATCH_DIVISOR in place, get remainder as BATCH_DIGITS digits */
mp_limb batch = mpn_div_batch(tmp->p, tmp->sz);
trim(tmp);
/* Convert remainder (0-999999999) to 9 digits using table lookup */
/* Extract last digit (9th) separately since 9 is odd */
/* Convert remainder to BATCH_DIGITS digits using table lookup */
#if (BATCH_DIGITS % 2) == 1
/* Extract last digit separately since BATCH_DIGITS is odd */
if (pos > 0) {
s[--pos] = '0' + (char)(batch % 10);
batch /= 10;
}
/* Extract remaining 8 digits as 4 pairs using lookup table */
for (int d = 0; d < 4 && pos >= 2; d++) {
#endif
/* Extract remaining digits as pairs using lookup table */
for (int d = 0; d < BATCH_DIGITS / 2 && pos >= 2; d++) {
mp_limb pair = batch % 100;
batch /= 100;
s[--pos] = digit_pairs[pair * 2 + 1];
mrbgems/mruby-bigint/core/bigint.h
-4
View File
@@ -30,10 +30,6 @@
#include <sys/types.h>
#if defined(MRB_INT32) && defined(_WIN32) && !defined(MRB_NO_MPZ64BIT)
#define MRB_NO_MPZ64BIT
#endif
#ifdef MRB_NO_MPZ64BIT
typedef uint16_t mp_limb;
typedef uint32_t mp_dbl_limb;