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| author | Andy Wingo <wingo@pobox.com> | 2013-10-03 21:35:21 +0200 |
|---|---|---|
| committer | Andy Wingo <wingo@pobox.com> | 2013-10-03 21:35:21 +0200 |
| commit | d7928d7c61f297dca574e20bb5815253e90b3a36 (patch) | |
| tree | f8b4ac0103eaded5c3b61573212ab0dc5fd5fcd1 /libguile/numbers.c | |
| parent | ae07b8e70bfc53220d7017bb7edcdb6c329d5bd5 (diff) | |
| parent | d7794a9d07ba657a29f7e608c3e558c437806def (diff) | |
Merge remote-tracking branch 'origin/stable-2.0'
Conflicts:
libguile/deprecated.h
libguile/programs.c
libguile/programs.h
Diffstat (limited to 'libguile/numbers.c')
| -rw-r--r-- | libguile/numbers.c | 11 |
1 files changed, 7 insertions, 4 deletions
diff --git a/libguile/numbers.c b/libguile/numbers.c index 7ccbeecf3..b91f4c308 100644 --- a/libguile/numbers.c +++ b/libguile/numbers.c @@ -4977,11 +4977,14 @@ left_shift_exact_integer (SCM n, long count) { scm_t_inum nn = SCM_I_INUM (n); - /* Left shift of count >= SCM_I_FIXNUM_BIT-1 will always + /* Left shift of count >= SCM_I_FIXNUM_BIT-1 will almost[*] always overflow a non-zero fixnum. For smaller shifts we check the bits going into positions above SCM_I_FIXNUM_BIT-1. If they're all 0s for nn>=0, or all 1s for nn<0 then there's no overflow. - Those bits are "nn >> (SCM_I_FIXNUM_BIT-1 - count)". */ + Those bits are "nn >> (SCM_I_FIXNUM_BIT-1 - count)". + + [*] There's one exception: + (-1) << SCM_I_FIXNUM_BIT-1 == SCM_MOST_NEGATIVE_FIXNUM */ if (nn == 0) return n; @@ -4994,8 +4997,8 @@ left_shift_exact_integer (SCM n, long count) SCM result = scm_i_inum2big (nn); mpz_mul_2exp (SCM_I_BIG_MPZ (result), SCM_I_BIG_MPZ (result), count); - return result; - } + return scm_i_normbig (result); + } } else if (SCM_BIGP (n)) { |