randread: run 2x faster on 64-bit hosts, don't assume no padding bits

* gl/lib/rand-isaac.c: 	Remove the I/O; this belongs elsewhere.
Add support for ISAAC64.  Port to hosts with padding bits.
Add self to author list.  Include <limits.h>, for CHAR_BIT.
Don't include string.h, sys/time.h, unistd.h.
(min, just): New functions.
(IF32): New macros.
(ind, ISAAC_STEP, isaac_refill, mix, isaac_init, isaac_seed):
Add support for ISAAC64.  Port to hosts with padding bits.
(ind): Now an inline function rather than a macro; no need for it
to be a macro with modern compilers.
(ISAAC_STEP): Renamed from isaac_step, since it's not function-like.
Don't bother to pass args that are always the same.  All uses changed.
(ISAAC_STEP, ISAAC_SEED): Move to inside the only function body
that can use it.
(ISAAC_MIX): Renamed from isaac_mix, since it's now a macro and is
no longer function-like.  Don't bother saving and restoring state;
no longer needed now that we're not a function.  All uses changed.
(isaac_seed_start, isaac_seed_data, isaac_seed_finish): Remove.
(isaac_seed): Take just the one arg; the caller now sets s->m.
* gl/lib/rand-isaac.h: Use _GL_RAND_ISAAC_H to protect, instead
of RAND_ISAAC_H.  Try out " #" rather than "# " for indenting.
(ISAAC_BITS_LOG, ISAAC_BITS): New macros.
(ISAAC_WORDS_LOG): Renamed from ISAAC_LOG.
(isaac_word): New type.  All uses of uint32_t changed to isaac_word,
to support ISAAC64.
(struct isaac_state): Rename member MM to M, and make it public.
(isaac_seed, isaac_refill): Adjust to new API.
* gl/lib/randread.c: Include sys/time.h.
(get_nonce): New function, containing the nonce stuff that used
to be in rand-isaac.c but better belongs here.
(randread_new): Use it.
* gl/modules/randread (Depends-on): Add inline.
* gl/modules/randread-tests: New file.
* gl/tests/test-rand-isaac.c: New file.

1 files changed, 37 insertions, 16 deletions

diff --git a/gl/lib/rand-isaac.h b/gl/lib/rand-isaac.h
index 052dc9f3a..6e5af0676 100644
--- a/gl/lib/rand-isaac.h
+++ b/gl/lib/rand-isaac.h
@@ -1,4 +1,4 @@
-/* Bob Jenkins's cryptographic random number generator, ISAAC.
+/* Bob Jenkins's cryptographic random number generators, ISAAC and ISAAC64.
 
    Copyright (C) 1999-2005, 2009-2010 Free Software Foundation, Inc.
    Copyright (C) 1997, 1998, 1999 Colin Plumb.
@@ -16,29 +16,50 @@
    You should have received a copy of the GNU General Public License
    along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
-   Written by Colin Plumb.  */
+   Written by Colin Plumb and Paul Eggert.  */
 
-#ifndef RAND_ISAAC_H
-# define RAND_ISAAC_H
+#ifndef _GL_RAND_ISAAC_H
+#define _GL_RAND_ISAAC_H
 
-# include <stddef.h>
-# include <stdint.h>
+#include <stddef.h>
+#include <stdint.h>
 
-/* Size of the state tables to use.  ISAAC_LOG should be at least 3,
+/* Log base 2 of the number of useful bits in an ISAAC word.  It must
+   be either 5 or 6.  By default, this uses a value that should be
+   faster for this architecture.  */
+#ifndef ISAAC_BITS_LOG
+ #if SIZE_MAX >> 31 >> 31 < 3 /* SIZE_MAX < 2**64 - 1 */
+  #define ISAAC_BITS_LOG 5
+ #else
+  #define ISAAC_BITS_LOG 6
+ #endif
+#endif
+
+/* The number of bits in an ISAAC word.  */
+#define ISAAC_BITS (1 << ISAAC_BITS_LOG)
+
+#if ISAAC_BITS == 32
+  typedef uint_least32_t isaac_word;
+#else
+  typedef uint_least64_t isaac_word;
+#endif
+
+/* Size of the state tables to use.  ISAAC_WORDS_LOG should be at least 3,
    and smaller values give less security.  */
-# define ISAAC_LOG 8
-# define ISAAC_WORDS (1 << ISAAC_LOG)
-# define ISAAC_BYTES (ISAAC_WORDS * sizeof (uint32_t))
+#define ISAAC_WORDS_LOG 8
+#define ISAAC_WORDS (1 << ISAAC_WORDS_LOG)
+#define ISAAC_BYTES (ISAAC_WORDS * sizeof (isaac_word))
 
-/* RNG state variables.  The members of this structure are private.  */
+/* State variables for the random number generator.  The M member
+   should be seeded with nonce data before calling isaac_seed.  The
+   other members are private.  */
 struct isaac_state
   {
-    uint32_t mm[ISAAC_WORDS];	/* Main state array */
-    uint32_t iv[8];		/* Seeding initial vector */
-    uint32_t a, b, c;		/* Extra index variables */
+    isaac_word m[ISAAC_WORDS];	/* Main state array */
+    isaac_word a, b, c;		/* Extra variables */
   };
 
-void isaac_seed (struct isaac_state *, int, size_t);
-void isaac_refill (struct isaac_state *, uint32_t[ISAAC_WORDS]);
+void isaac_seed (struct isaac_state *);
+void isaac_refill (struct isaac_state *, isaac_word[ISAAC_WORDS]);
 
 #endif