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Start porting srfi-60 off the bad bignum interfaces

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* libguile/integers.h:
* libguile/integers.c (scm_integer_scan1_i):
(scm_integer_scan1_z): New internal functions.
* libguile/srfi-60.c (scm_srfi60_log2_binary_factors): Use scan1
functions.
(scm_srfi60_copy_bit): Use integers lib.
This commit is contained in:
Andy Wingo 2022-01-07 12:07:44 +01:00
parent bdddef3cfd
commit 399d0c8745
3 changed files with 31 additions and 48 deletions
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19
libguile/integers.c
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@ -3168,3 +3168,22 @@ scm_integer_inexact_sqrt_z (struct scm_bignum *k)
double result = ldexp (sqrt (signif), expon / 2);
return negative ? -result : result;
}
SCM
scm_integer_scan1_i (scm_t_inum n)
{
if (n == 0)
return SCM_I_MAKINUM (-1);
n = n ^ (n-1); /* 1 bits for each low 0 and lowest 1 */
return scm_integer_logcount_i (n >> 1);
}
SCM
scm_integer_scan1_z (struct scm_bignum *n)
{
mpz_t zn;
alias_bignum_to_mpz (n, zn);
unsigned long pos = mpz_scan1 (zn, 0L);
scm_remember_upto_here_1 (n);
return ulong_to_scm (pos);
}