diff options
Diffstat (limited to 'libguile/numbers.c')
| -rw-r--r-- | libguile/numbers.c | 40 |
1 files changed, 38 insertions, 2 deletions
diff --git a/libguile/numbers.c b/libguile/numbers.c index 458a92f1c..d09b7c575 100644 --- a/libguile/numbers.c +++ b/libguile/numbers.c @@ -6767,7 +6767,25 @@ scm_less_p (SCM x, SCM y) return scm_from_bool (sgn > 0); } else if (SCM_REALP (y)) - return scm_from_bool ((double) xx < SCM_REAL_VALUE (y)); + { + /* We can safely take the ceiling of y without changing the + result of x<y, given that x is an integer. */ + double yy = ceil (SCM_REAL_VALUE (y)); + + /* In the following comparisons, it's important that the right + hand side always be a power of 2, so that it can be + losslessly converted to a double even on 64-bit + machines. */ + if (yy >= (double) (SCM_MOST_POSITIVE_FIXNUM+1)) + return SCM_BOOL_T; + else if (!(yy > (double) SCM_MOST_NEGATIVE_FIXNUM)) + /* The condition above is carefully written to include the + case where yy==NaN. */ + return SCM_BOOL_F; + else + /* yy is a finite integer that fits in an inum. */ + return scm_from_bool (xx < (scm_t_inum) yy); + } else if (SCM_FRACTIONP (y)) { /* "x < a/b" becomes "x*b < a" */ @@ -6810,7 +6828,25 @@ scm_less_p (SCM x, SCM y) else if (SCM_REALP (x)) { if (SCM_I_INUMP (y)) - return scm_from_bool (SCM_REAL_VALUE (x) < (double) SCM_I_INUM (y)); + { + /* We can safely take the floor of x without changing the + result of x<y, given that y is an integer. */ + double xx = floor (SCM_REAL_VALUE (x)); + + /* In the following comparisons, it's important that the right + hand side always be a power of 2, so that it can be + losslessly converted to a double even on 64-bit + machines. */ + if (xx < (double) SCM_MOST_NEGATIVE_FIXNUM) + return SCM_BOOL_T; + else if (!(xx < (double) (SCM_MOST_POSITIVE_FIXNUM+1))) + /* The condition above is carefully written to include the + case where xx==NaN. */ + return SCM_BOOL_F; + else + /* xx is a finite integer that fits in an inum. */ + return scm_from_bool ((scm_t_inum) xx < SCM_I_INUM (y)); + } else if (SCM_BIGP (y)) { int cmp; |