factorial: Fix usage message to fit in with conventions.

[u/mdw/catacomb] / field.h

diff --git a/field.h b/field.h
index 5790284..c2ad26e 100644 (file)
--- a/field.h
+++ b/field.h
@@ -1,6 +1,6 @@
 /* -*-c-*-
  *
- * $Id: field.h,v 1.11 2004/04/08 01:36:15 mdw Exp $
+ * $Id$
  *
  * Definitions for field arithmetic
  *
@@ -56,6 +56,7 @@ typedef struct field {
   mp *m;                               /* Modulus (prime and binary) */
   unsigned long nbits;                 /* Length of field element in bits */
   size_t noctets;                      /* Length of element in octets */
+  mp *q;                               /* Number of elements in field */
 } field;
 
 enum {
@@ -170,6 +171,25 @@ extern int field_samep(field */*f*/, field */*g*/);
 
 extern int field_stdsamep(field */*f*/, field */*g*/);
 
+/*----- Arithmetic --------------------------------------------------------*/
+
+/* --- @field_exp@ --- *
+ *
+ * Arguments:  @field *f@ = pointer to field
+ *             @mp *d@ = fake destination
+ *             @mp *a@ = base
+ *             @mp *e@ = exponent
+ *
+ * Returns:    Result, %$a^e$%.
+ *
+ * Use:                Exponentiation in a finite field.  Note that all quantities
+ *             are in internal format.  This is a generic implementation
+ *             suitable for use with all fields and is not intended to be
+ *             optimal.
+ */
+
+extern mp *field_exp(field */*f*/, mp */*d*/, mp */*a*/, mp */*e*/);
+
 /*----- Creating fields ---------------------------------------------------*/
 
 /* --- @field_prime@ --- *
@@ -188,7 +208,7 @@ extern field *field_prime(mp */*p*/);
  *
  * Arguments:  @mp *p@ = the characteristic of the field
  *
- * Returns:    A pointer to the field.
+ * Returns:    A pointer to the field, or null.
  *
  * Use:                Creates a field structure for a prime field of size %$p$%,
  *             using efficient reduction for nice primes.