[Guile-commits] GNU Guile branch, master, updated. release_1-9-11-233-g2af6e13

[Andy Wingo]

This is an automated email from the git hooks/post-receive script. It was
generated because a ref change was pushed to the repository containing
the project "GNU Guile".

http://git.savannah.gnu.org/cgit/guile.git/commit/?id=2af6e1351da68c09d6b50be535901a4f85a4807a

The branch, master has been updated
       via  2af6e1351da68c09d6b50be535901a4f85a4807a (commit)
      from  7387c231ee382a36a13a04c9f3b247b1667f0397 (commit)

Those revisions listed above that are new to this repository have
not appeared on any other notification email; so we list those
revisions in full, below.

- Log -----------------------------------------------------------------
commit 2af6e1351da68c09d6b50be535901a4f85a4807a
Author: Andreas Rottmann <address@hidden>
Date:   Sun Aug 1 21:53:29 2010 +0200

    Fix the range of `random' on 64-bit platforms
    
    For > 32 bit integers still in the fixnum range, scm_random() would
    return random numbers with a lower range than specified.
    
    * libguile/random.c (scm_i_mask32): New static inline function.
      (scm_c_random): Use `scm_i_mask32'.
      (scm_c_random64): New function, 64-bit variant of scm_c_random.
      (scm_random): Use `scm_c_random64' instead of forming the 64-bit random
      number in a bogus way.
    * libguile/random.h: Added `scm_c_random64'.

-----------------------------------------------------------------------

Summary of changes:
 libguile/random.c |   42 +++++++++++++++++++++++++++---------------
 libguile/random.h |    1 +
 2 files changed, 28 insertions(+), 15 deletions(-)

diff --git a/libguile/random.c b/libguile/random.c
index 83870f6..c0a3e04 100644
--- a/libguile/random.c
+++ b/libguile/random.c
@@ -241,21 +241,42 @@ scm_c_exp1 (scm_t_rstate *state)
 
 unsigned char scm_masktab[256];
 
-scm_t_uint32
-scm_c_random (scm_t_rstate *state, scm_t_uint32 m)
+static inline scm_t_uint32
+scm_i_mask32 (scm_t_uint32 m)
 {
-  scm_t_uint32 r, mask;
-  mask = (m < 0x100
+  return (m < 0x100
          ? scm_masktab[m]
          : (m < 0x10000
             ? scm_masktab[m >> 8] << 8 | 0xff
             : (m < 0x1000000
                ? scm_masktab[m >> 16] << 16 | 0xffff
                : scm_masktab[m >> 24] << 24 | 0xffffff)));
+}
+
+scm_t_uint32
+scm_c_random (scm_t_rstate *state, scm_t_uint32 m)
+{
+  scm_t_uint32 r, mask = scm_i_mask32 (m);
   while ((r = state->rng->random_bits (state) & mask) >= m);
   return r;
 }
 
+scm_t_uint64
+scm_c_random64 (scm_t_rstate *state, scm_t_uint64 m)
+{
+  scm_t_uint64 r;
+  scm_t_uint32 mask;
+
+  if (m <= SCM_T_UINT32_MAX)
+    return scm_c_random (state, (scm_t_uint32) m);
+  
+  mask = scm_i_mask32 (m >> 32);
+  while ((r = ((scm_t_uint64) (state->rng->random_bits (state) & mask) << 32)
+          | state->rng->random_bits (state)) >= m)
+    ;
+  return r;
+}
+
 /*
   SCM scm_c_random_bignum (scm_t_rstate *state, SCM m)
 
@@ -377,17 +398,8 @@ SCM_DEFINE (scm_random, "random", 1, 1, 0,
       return scm_from_uint32 (scm_c_random (SCM_RSTATE (state),
                                             (scm_t_uint32) m));
 #elif SCM_SIZEOF_UNSIGNED_LONG <= 8
-      if (m <= SCM_T_UINT32_MAX)
-        return scm_from_uint32 (scm_c_random (SCM_RSTATE (state),
-                                              (scm_t_uint32) m));
-      else
-        {
-          scm_t_uint64 upper, lower;
-          
-          upper = scm_c_random (SCM_RSTATE (state), (scm_t_uint32) (m >> 32));
-          lower = scm_c_random (SCM_RSTATE (state), SCM_T_UINT32_MAX);
-          return scm_from_uint64 ((upper << 32) | lower);
-        }
+      return scm_from_uint64 (scm_c_random64 (SCM_RSTATE (state),
+                                              (scm_t_uint64) m));
 #else
 #error "Cannot deal with this platform's unsigned long size"
 #endif
diff --git a/libguile/random.h b/libguile/random.h
index 512b7d2..2f1f0f6 100644
--- a/libguile/random.h
+++ b/libguile/random.h
@@ -67,6 +67,7 @@ SCM_API double scm_c_uniform01 (scm_t_rstate *);
 SCM_API double scm_c_normal01 (scm_t_rstate *);
 SCM_API double scm_c_exp1 (scm_t_rstate *);
 SCM_API scm_t_uint32 scm_c_random (scm_t_rstate *, scm_t_uint32 m);
+SCM_API scm_t_uint64 scm_c_random64 (scm_t_rstate *state, scm_t_uint64 m);
 SCM_API SCM scm_c_random_bignum (scm_t_rstate *, SCM m);
 
 


hooks/post-receive
-- 
GNU Guile