diff options
author | Andy Wingo <wingo@pobox.com> | 2021-12-19 11:06:36 +0100 |
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committer | Andy Wingo <wingo@pobox.com> | 2022-01-13 09:37:16 +0100 |
commit | 89cd48fcac6c8b11a1a1cb155d3ddf6747719e7c (patch) | |
tree | 1a429a377d5f2fa90c9284d0b148a1d30160dcd7 /libguile | |
parent | 6298d731155ea35aecf68f21af81f1c4fd2f5e87 (diff) | |
download | guile-89cd48fcac6c8b11a1a1cb155d3ddf6747719e7c.tar.gz |
Implement scm_logbit_p with new integer library
* libguile/integers.c (scm_integer_logbit_ui, scm_integer_logbit_uz):
* libguile/integers.h: Declare the new internal functions.
* libguile/numbers.c (scm_logbit_p): Use new internal functions.
Diffstat (limited to 'libguile')
-rw-r--r-- | libguile/integers.c | 20 | ||||
-rw-r--r-- | libguile/integers.h | 3 | ||||
-rw-r--r-- | libguile/numbers.c | 18 |
3 files changed, 25 insertions, 16 deletions
diff --git a/libguile/integers.c b/libguile/integers.c index ff5499af9..fc71c7acc 100644 --- a/libguile/integers.c +++ b/libguile/integers.c @@ -2008,3 +2008,23 @@ scm_integer_logtest_zz (SCM x, SCM y) { return scm_is_eq (scm_integer_logand_zz (x, y), SCM_INUM0); } + +int +scm_integer_logbit_ui (unsigned long index, scm_t_inum n) +{ + if (index < SCM_LONG_BIT) + /* Assume two's complement representation. */ + return (n >> index) & 1; + else + return n < 0; +} + +int +scm_integer_logbit_uz (unsigned long index, SCM n) +{ + mpz_t zn; + alias_bignum_to_mpz (scm_bignum (n), zn); + int val = mpz_tstbit (zn, index); + scm_remember_upto_here_1 (n); + return val; +} diff --git a/libguile/integers.h b/libguile/integers.h index 56334f0a8..feba5963f 100644 --- a/libguile/integers.h +++ b/libguile/integers.h @@ -148,6 +148,9 @@ SCM_INTERNAL int scm_integer_logtest_ii (scm_t_inum x, scm_t_inum y); SCM_INTERNAL int scm_integer_logtest_zi (SCM x, scm_t_inum y); SCM_INTERNAL int scm_integer_logtest_zz (SCM x, SCM y); +SCM_INTERNAL int scm_integer_logbit_ui (unsigned long bit, scm_t_inum n); +SCM_INTERNAL int scm_integer_logbit_uz (unsigned long bit, SCM n); + #endif /* SCM_INTEGERS_H */ diff --git a/libguile/numbers.c b/libguile/numbers.c index 26d1c061f..548618e74 100644 --- a/libguile/numbers.c +++ b/libguile/numbers.c @@ -3155,23 +3155,9 @@ SCM_DEFINE (scm_logbit_p, "logbit?", 2, 0, 0, iindex = scm_to_ulong (index); if (SCM_I_INUMP (j)) - { - if (iindex < SCM_LONG_BIT - 1) - /* Arrange for the number to be converted to unsigned before - checking the bit, to ensure that we're testing the bit in a - two's complement representation (regardless of the native - representation. */ - return scm_from_bool ((1UL << iindex) & SCM_I_INUM (j)); - else - /* Portably check the sign. */ - return scm_from_bool (SCM_I_INUM (j) < 0); - } + return scm_from_bool (scm_integer_logbit_ui (iindex, SCM_I_INUM (j))); else if (SCM_BIGP (j)) - { - int val = mpz_tstbit (SCM_I_BIG_MPZ (j), iindex); - scm_remember_upto_here_1 (j); - return scm_from_bool (val); - } + return scm_from_bool (scm_integer_logbit_uz (iindex, j)); else SCM_WRONG_TYPE_ARG (SCM_ARG2, j); } |