hash: use full width unsigned type for hash values.

Throughout the hashing framework, hashes are reduced into the
fixnum range, and returned as cnum.  This is not necessary;
only the hash-eql and hash-equal functions need to reduce
hashes to fixnums. Let's make it ucnum everywhere else, using
its full range (no reduction into the [0, NUM_MAX) range).

* hash.c (struct hash_ops): hash_fun function pointer returns
ucnum instead of cnum.
(hash_double): Return unreduced ucnum. Obsolete #ifdef-s
removed; the ucnum type gives us a pointer-wide unsigned
integer on all platforms.
(equal_hash, eql_hash): Return ucnum. Don't reduce values to
fixnum range. Some of the way we combine hashes from recursive
calls changes; we multiply by at most 2 not to lose too many
bits.
(eql_hash_op, cobj_eq_hash_op, hash_hash_op): Return ucnum.

* hash.h (equal_hash): Declaration updated.

* lib.c (cobj_handle_hash_op): Return value changes to ucnum.

* lib.h (struct cobj_ops): Hash function pointer's return
type changes.
(cobj_eq_hash_op, cobj_handle_hash_op): Declarations updated.

* struct.c (struct_inst_hash): Return value changes to ucnum.

1 files changed, 3 insertions, 3 deletions

diff --git a/lib.h b/lib.h
index 384812d2..718e2c86 100644
--- a/lib.h
+++ b/lib.h
@@ -244,7 +244,7 @@ struct cobj_ops {
   void (*print)(val self, val stream, val pretty, struct strm_ctx *);
   void (*destroy)(val self);
   void (*mark)(val self);
-  cnum (*hash)(val self, int *count, ucnum seed);
+  ucnum (*hash)(val self, int *count, ucnum seed);
   val (*equalsub)(val self);
 };
 
@@ -265,8 +265,8 @@ val cobj_equal_handle_op(val left, val right);
 void cobj_destroy_stub_op(val);
 void cobj_destroy_free_op(val);
 void cobj_mark_op(val);
-cnum cobj_eq_hash_op(val, int *, ucnum);
-cnum cobj_handle_hash_op(val, int *, ucnum);
+ucnum cobj_eq_hash_op(val, int *, ucnum);
+ucnum cobj_handle_hash_op(val, int *, ucnum);
 
 struct env {
   obj_common;