Move ISAAC code out of shred.c.

diff --git a/src/rand-isaac.h b/src/rand-isaac.h
new file mode 100644 (file)
index 0000000..e6413f9
--- /dev/null
+++ b/src/rand-isaac.h
@@ -0,0 +1,93 @@
+/* rand-isaac.h - header for ISAAC
+
+   Copyright (C) 1999-2005 Free Software Foundation, Inc.
+   Copyright (C) 1997, 1998, 1999 Colin Plumb.
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 2, or (at your option)
+   any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program; if not, write to the Free Software Foundation,
+   Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+
+   Written by Colin Plumb.  */
+
+/* Size of the state tables to use. */
+/* (You may change ISAAC_LOG but it should be >= 3, and smaller values
+ * give less security) */
+#ifndef ISAAC_LOG
+# define ISAAC_LOG 8
+#endif
+#define ISAAC_MAX_WORDS (1 << ISAAC_LOG)
+#define ISAAC_MAX_BYTES (ISAAC_MAX_WORDS * sizeof (uint32_t))
+
+/* RNG state variables */
+struct isaac_state
+  {
+    uint32_t iv[8];                /* Seeding initial vector */
+    uint32_t a, b, c;              /* Extra index variables */
+    uint32_t words;                 /* Words in main state array */
+    uint32_t log;                   /* Log of words */
+    uint32_t mm[ISAAC_MAX_WORDS];   /* Main state array */
+  };
+
+/* This index operation is more efficient on many processors */
+#define ind(words, mm, x) \
+  (* (uint32_t *) ((char *) (mm) \
+                  + ((x) & (words - 1) * sizeof (uint32_t))))
+
+/*
+ * The central step. This uses two temporaries, x and y. s is the
+ * state, while m is a pointer to the current word. off is the offset
+ * from m to the word s->words/2 words away in the mm array, i.e.
+ * +/- s->words/2.
+ */
+#define isaac_step(s, mix, a, b, m, off, r)  \
+( \
+  a = ((a) ^ (mix)) + (m)[off], \
+  x = *(m), \
+  *(m) = y = ind (s->words, s->mm, x) + (a) + (b),  \
+  *(r) = b = ind (s->words, s->mm, (y) >> s->log) + x      \
+)
+
+struct isaac_state *
+isaac_new (struct isaac_state *s, int words);
+void
+isaac_copy (struct isaac_state *dst, struct isaac_state *src);
+void
+isaac_refill (struct isaac_state *s, uint32_t r[/* s->words */]);
+void
+isaac_mix (struct isaac_state *s, uint32_t const seed[/* s->words */]);
+void
+isaac_init (struct isaac_state *s, uint32_t const *seed, size_t seedsize);
+void
+isaac_seed_start (struct isaac_state *s);
+void
+isaac_seed_data (struct isaac_state *s, void const *buffer, size_t size);
+void
+isaac_seed_finish (struct isaac_state *s);
+#define ISAAC_SEED(s,x) isaac_seed_data (s, &(x), sizeof (x))
+void
+isaac_seed (struct isaac_state *s);
+
+/* Single-word RNG built on top of ISAAC */
+struct irand_state
+{
+  uint32_t r[ISAAC_MAX_WORDS];
+  unsigned int numleft;
+  struct isaac_state *s;
+};
+
+void
+irand_init (struct irand_state *r, struct isaac_state *s);
+uint32_t
+irand32 (struct irand_state *r);
+uint32_t
+irand_mod (struct irand_state *r, uint32_t n);