updates.

[silc.git] / lib / silcmath / mpbin.c

diff --git a/lib/silcmath/mpbin.c b/lib/silcmath/mpbin.c
index 6e0e6eadb384663e068cf60c28445d6f26c2d86e..8b598aa1a1f4759196ee96291b3510cd95dcba27 100644 (file)
--- a/lib/silcmath/mpbin.c
+++ b/lib/silcmath/mpbin.c
@@ -4,7 +4,7 @@
 
   Author: Pekka Riikonen <priikone@poseidon.pspt.fi>
 
-  Copyright (C) 2000 Pekka Riikonen
+  Copyright (C) 2000 - 2001 Pekka Riikonen
 
   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
@@ -22,18 +22,20 @@
 #include "silcincludes.h"
 
 /* Encodes MP integer into binary data. Returns allocated data that
-   must be free'd by the caller. */
+   must be free'd by the caller. If `len' is provided the destination
+   buffer is allocated that large. If zero then the size is approximated. */
 
-unsigned char *silc_mp_mp2bin(SilcInt *val, unsigned int *ret_len)
+unsigned char *silc_mp_mp2bin(SilcInt *val, unsigned int len,
+                             unsigned int *ret_len)
 {
   int i;
   unsigned int size;
   unsigned char *ret;
   SilcInt tmp;
 
-  size = (silc_mp_sizeinbase(val, 2) + 7) / 8;
+  size = (len ? len : ((silc_mp_sizeinbase(val, 2) + 7) / 8));
   ret = silc_calloc(size, sizeof(*ret));
-
+  
   silc_mp_init_set(&tmp, val);
 
   for (i = size; i > 0; i--) {
@@ -49,6 +51,27 @@ unsigned char *silc_mp_mp2bin(SilcInt *val, unsigned int *ret_len)
   return ret;
 }
 
+/* Samve as above but does not allocate any memory.  The encoded data is
+   returned into `dst' and it's length to the `ret_len'. If `dst_len is
+   non-zero then the destination buffer is assumbed to be that large. */
+
+void silc_mp_mp2bin_noalloc(SilcInt *val, unsigned char *dst,
+                           unsigned int dst_len)
+{
+  int i;
+  unsigned int size = dst_len;
+  SilcInt tmp;
+
+  silc_mp_init_set(&tmp, val);
+
+  for (i = size; i > 0; i--) {
+    dst[i - 1] = (unsigned char)(silc_mp_get_ui(&tmp) & 0xff);
+    silc_mp_fdiv_q_2exp(&tmp, &tmp, 8);
+  }
+
+  silc_mp_clear(&tmp);
+}
+
 /* Decodes binary data into MP integer. The integer sent as argument
    must be initialized. */