X-Git-Url: https://git.distorted.org.uk/u/mdw/catacomb/blobdiff_plain/fa16f6d37b362288e3086fbb34344bc817c09796..f09e814abfcb58c0bb5423589e2940c205106e8d:/mp-io.c

diff --git a/mp-io.c b/mp-io.c
index c510649..2f87892 100644
--- a/mp-io.c
+++ b/mp-io.c
@@ -1,6 +1,6 @@
 /* -*-c-*-
  *
- * $Id: mp-io.c,v 1.4 2000/06/17 11:45:09 mdw Exp $
+ * $Id: mp-io.c,v 1.5 2002/10/06 22:52:50 mdw Exp $
  *
  * Loading and storing of multiprecision integers
  *
@@ -30,6 +30,9 @@
 /*----- Revision history --------------------------------------------------* 
  *
  * $Log: mp-io.c,v $
+ * Revision 1.5  2002/10/06 22:52:50  mdw
+ * Pile of changes for supporting two's complement properly.
+ *
  * Revision 1.4  2000/06/17 11:45:09  mdw
  * Major memory management overhaul.  Added arena support.  Use the secure
  * arena for secret integers.  Replace and improve the MP management macros
@@ -69,6 +72,23 @@ size_t mp_octets(const mp *m)
   return (sz);
 }
 
+/* --- @mp_octets2c@ --- *
+ *
+ * Arguments:	@const mp *m@ = a multiprecision integer
+ *
+ * Returns:	The number of octets required to represent @m@.
+ *
+ * Use:		Calculates the external storage required for a multiprecision
+ *		integer represented as two's complement.
+ */
+
+size_t mp_octets2c(const mp *m)
+{
+  size_t sz;
+  MPX_OCTETS2C(sz, m->v, m->vl);
+  return (sz);
+}
+
 /* --- @mp_bits@ --- *
  *
  * Arguments:	@const mp *m@ = a multiprecision integer
@@ -176,4 +196,108 @@ void mp_storeb(const mp *m, void *pv, size_t sz)
   mpx_storeb(m->v, m->vl, pv, sz);
 }
 
+/* --- @mp_loadl2c@ --- *
+ *
+ * Arguments:	@mp *d@ = destination
+ *		@const void *pv@ = pointer to source data
+ *		@size_t sz@ = size of the source data
+ *
+ * Returns:	Resulting multiprecision number.
+ *
+ * Use:		Loads a multiprecision number from an array of octets as
+ *		two's complement.  The first byte in the array is the least
+ *		significant.
+ */
+
+mp *mp_loadl2c(mp *d, const void *pv, size_t sz)
+{
+  const octet *ov = pv;
+  MP_DEST(d, MPW_RQ(sz), MP_UNDEF);
+  if (!sz || !(ov[sz - 1] & 0x80)) {
+    mpx_loadl(d->v, d->vl, pv, sz);
+    d->f &= ~MP_NEG;
+  } else {
+    mpx_loadl2cn(d->v, d->vl, pv, sz);
+    d->f |= MP_NEG;
+  }
+  d->f &= ~MP_UNDEF;
+  mp_shrink(d);
+  return (d);
+}
+
+/* --- @mp_storel2c@ --- *
+ *
+ * Arguments:	@const mp *m@ = source
+ *		@void *pv@ = pointer to output array
+ *		@size_t sz@ = size of the output array
+ *
+ * Returns:	---
+ *
+ * Use:		Stores a multiprecision number in an array of octets as two's
+ *		complement.  The first byte in the array is the least
+ *		significant.  If the array is too small to represent the
+ *		number, high-order bits are truncated; if the array is too
+ *		large, high order bytes are sign-extended.
+ */
+
+void mp_storel2c(const mp *m, void *pv, size_t sz)
+{
+  if (m->f & MP_NEG)
+    mpx_storel2cn(m->v, m->vl, pv, sz);
+  else
+    mpx_storel(m->v, m->vl, pv, sz);
+}
+
+/* --- @mp_loadb2c@ --- *
+ *
+ * Arguments:	@mp *d@ = destination
+ *		@const void *pv@ = pointer to source data
+ *		@size_t sz@ = size of the source data
+ *
+ * Returns:	Resulting multiprecision number.
+ *
+ * Use:		Loads a multiprecision number from an array of octets as
+ *		two's complement.  The last byte in the array is the least
+ *		significant.
+ */
+
+mp *mp_loadb2c(mp *d, const void *pv, size_t sz)
+{
+  const octet *ov = pv;
+  MP_DEST(d, MPW_RQ(sz), MP_UNDEF);
+  if (!sz || !(ov[0] & 0x80)) {
+    mpx_loadl(d->v, d->vl, pv, sz);
+    d->f &= ~MP_NEG;
+  } else {
+    mpx_loadl2cn(d->v, d->vl, pv, sz);
+    d->f |= MP_NEG;
+  }
+  d->f &= ~MP_UNDEF;
+  mp_shrink(d);
+  return (d);
+}
+
+/* --- @mp_storeb2c@ --- *
+ *
+ * Arguments:	@const mp *m@ = source
+ *		@void *pv@ = pointer to output array
+ *		@size_t sz@ = size of the output array
+ *
+ * Returns:	---
+ *
+ * Use:		Stores a multiprecision number in an array of octets, as
+ *		two's complement.  The last byte in the array is the least
+ *		significant.  If the array is too small to represent the
+ *		number, high-order bits are truncated; if the array is too
+ *		large, high order bytes are sign-extended.
+ */
+
+void mp_storeb2c(const mp *m, void *pv, size_t sz)
+{
+  if (m->f & MP_NEG)
+    mpx_storeb2cn(m->v, m->vl, pv, sz);
+  else
+    mpx_storeb(m->v, m->vl, pv, sz);
+}
+
 /*----- That's all, folks -------------------------------------------------*/