diff options
Diffstat (limited to 'libguile/numbers.c')
-rw-r--r-- | libguile/numbers.c | 13 |
1 files changed, 11 insertions, 2 deletions
diff --git a/libguile/numbers.c b/libguile/numbers.c index 21dcdb62c..a11ed3a8c 100644 --- a/libguile/numbers.c +++ b/libguile/numbers.c @@ -5053,6 +5053,11 @@ round_right_shift_exact_integer (SCM n, long count) assert (0); } +/* 'scm_ash' and 'scm_round_ash' assume that fixnums fit within a long, + and moreover that they can be negated without overflow. */ +verify (SCM_MOST_NEGATIVE_FIXNUM >= LONG_MIN + 1 + && SCM_MOST_POSITIVE_FIXNUM <= LONG_MAX); + SCM_DEFINE (scm_ash, "ash", 2, 0, 0, (SCM n, SCM count), "Return @math{floor(@var{n} * 2^@var{count})}.\n" @@ -5078,7 +5083,9 @@ SCM_DEFINE (scm_ash, "ash", 2, 0, 0, if (SCM_I_INUMP (count)) /* fast path, not strictly needed */ bits_to_shift = SCM_I_INUM (count); - else if (scm_is_signed_integer (count, LONG_MIN, LONG_MAX)) + else if (scm_is_signed_integer (count, LONG_MIN + 1, LONG_MAX)) + /* We exclude LONG_MIN to ensure that 'bits_to_shift' can be + negated without overflowing. */ bits_to_shift = scm_to_long (count); else if (scm_is_false (scm_positive_p (scm_sum (scm_integer_length (n), count)))) @@ -5130,7 +5137,9 @@ SCM_DEFINE (scm_round_ash, "round-ash", 2, 0, 0, if (SCM_I_INUMP (count)) /* fast path, not strictly needed */ bits_to_shift = SCM_I_INUM (count); - else if (scm_is_signed_integer (count, LONG_MIN, LONG_MAX)) + else if (scm_is_signed_integer (count, LONG_MIN + 1, LONG_MAX)) + /* We exclude LONG_MIN to ensure that 'bits_to_shift' can be + negated without overflowing. */ bits_to_shift = scm_to_long (count); else if (scm_is_true (scm_negative_p (scm_sum (scm_integer_length (n), count))) |