add isl_val_int_from_chunks and isl_val_get_abs_num_chunks

These allow for a backend independent way of converting from/to
multiple precision integers.

Requested-by: Tobias Grosser <tobias@grosser.es>
Signed-off-by: Sven Verdoolaege <skimo@kotnet.org>

diff --git a/doc/user.pod b/doc/user.pod
index 9fbff36..47af664 100644 (file)
--- a/doc/user.pod
+++ b/doc/user.pod
@@ -363,8 +363,14 @@ Specific integer values can be created using the following functions.
                long i);
        __isl_give isl_val *isl_val_int_from_ui(isl_ctx *ctx,
                unsigned long u);
+       __isl_give isl_val *isl_val_int_from_chunks(isl_ctx *ctx,
+               size_t n, size_t size, const void *chunks);
 
-They can be copied and freed using the following functions.
+The function C<isl_val_int_from_chunks> constructs an C<isl_val>
+from the C<n> I<digits>, each consisting of C<size> bytes, stored at C<chunks>.
+The least significant digit is assumed to be stored first.
+
+Value objects can be copied and freed using the following functions.
 
        #include <isl/val.h>
        __isl_give isl_val *isl_val_copy(__isl_keep isl_val *v);
@@ -377,9 +383,20 @@ They can be inspected using the following functions.
        long isl_val_get_num_si(__isl_keep isl_val *v);
        long isl_val_get_den_si(__isl_keep isl_val *v);
        double isl_val_get_d(__isl_keep isl_val *v);
-
-Note that C<isl_val_get_num_si>, C<isl_val_get_den_si> and
-C<isl_val_get_d> can only be applied to rational values.
+       size_t isl_val_n_abs_num_chunks(__isl_keep isl_val *v,
+               size_t size);
+       int isl_val_get_abs_num_chunks(__isl_keep isl_val *v,
+               size_t size, void *chunks);
+
+C<isl_val_n_abs_num_chunks> returns the number of I<digits>
+of C<size> bytes needed to store the absolute value of the
+numerator of C<v>.
+C<isl_val_get_abs_num_chunks> stores these digits at C<chunks>,
+which is assumed to have been preallocated by the caller.
+The least significant digit is stored first.
+Note that C<isl_val_get_num_si>, C<isl_val_get_den_si>,
+C<isl_val_get_d>, C<isl_val_n_abs_num_chunks>
+and C<isl_val_get_abs_num_chunks> can only be applied to rational values.
 
 An C<isl_val> can be modified using the following function.
 

diff --git a/include/isl/val.h b/include/isl/val.h
index f762a7b..caf506d 100644 (file)
--- a/include/isl/val.h
+++ b/include/isl/val.h
@@ -27,6 +27,8 @@ __isl_give isl_val *isl_val_infty(isl_ctx *ctx);
 __isl_give isl_val *isl_val_neginfty(isl_ctx *ctx);
 __isl_give isl_val *isl_val_int_from_si(isl_ctx *ctx, long i);
 __isl_give isl_val *isl_val_int_from_ui(isl_ctx *ctx, unsigned long u);
+__isl_give isl_val *isl_val_int_from_chunks(isl_ctx *ctx, size_t n,
+       size_t size, const void *chunks);
 
 __isl_give isl_val *isl_val_copy(__isl_keep isl_val *v);
 void *isl_val_free(__isl_take isl_val *v);
@@ -35,6 +37,9 @@ isl_ctx *isl_val_get_ctx(__isl_keep isl_val *val);
 long isl_val_get_num_si(__isl_keep isl_val *v);
 long isl_val_get_den_si(__isl_keep isl_val *v);
 double isl_val_get_d(__isl_keep isl_val *v);
+size_t isl_val_n_abs_num_chunks(__isl_keep isl_val *v, size_t size);
+int isl_val_get_abs_num_chunks(__isl_keep isl_val *v, size_t size,
+       void *chunks);
 
 __isl_give isl_val *isl_val_set_si(__isl_take isl_val *v, long i);
 

diff --git a/isl_val_gmp.c b/isl_val_gmp.c
index aed8bb1..42e8d44 100644 (file)
--- a/isl_val_gmp.c
+++ b/isl_val_gmp.c
@@ -1,3 +1,4 @@
+#include <string.h>
 #include <isl/val_gmp.h>
 #include <isl_val_private.h>
 
@@ -62,3 +63,66 @@ int isl_val_get_den_gmp(__isl_keep isl_val *v, mpz_t z)
        mpz_set(z, v->d);
        return 0;
 }
+
+/* Return a reference to an isl_val representing the unsigned
+ * integer value stored in the "n" chunks of size "size" at "chunks".
+ * The least significant chunk is assumed to be stored first.
+ */
+__isl_give isl_val *isl_val_int_from_chunks(isl_ctx *ctx, size_t n,
+       size_t size, const void *chunks)
+{
+       isl_val *v;
+
+       v = isl_val_alloc(ctx);
+       if (!v)
+               return NULL;
+
+       mpz_import(v->n, n, -1, size, 0, 0, chunks);
+       isl_int_set_si(v->d, 1);
+
+       return v;
+}
+
+/* Return the number of chunks of size "size" required to
+ * store the absolute value of the numerator of "v".
+ */
+size_t isl_val_n_abs_num_chunks(__isl_keep isl_val *v, size_t size)
+{
+       if (!v)
+               return 0;
+
+       if (!isl_val_is_rat(v))
+               isl_die(isl_val_get_ctx(v), isl_error_invalid,
+                       "expecting rational value", return 0);
+
+       size *= 8;
+       return (mpz_sizeinbase(v->n, 2) + size - 1) / size;
+}
+
+/* Store a representation of the absolute value of the numerator of "v"
+ * in terms of chunks of size "size" at "chunks".
+ * The least significant chunk is stored first.
+ * The number of chunks in the result can be obtained by calling
+ * isl_val_n_abs_num_chunks.  The user is responsible for allocating
+ * enough memory to store the results.
+ *
+ * In the special case of a zero value, isl_val_n_abs_num_chunks will
+ * return one, while mpz_export will not fill in any chunks.  We therefore
+ * do it ourselves.
+ */
+int isl_val_get_abs_num_chunks(__isl_keep isl_val *v, size_t size,
+       void *chunks)
+{
+       if (!v || !chunks)
+               return -1;
+
+       if (!isl_val_is_rat(v))
+               isl_die(isl_val_get_ctx(v), isl_error_invalid,
+                       "expecting rational value", return -1);
+
+       mpz_export(chunks, NULL, -1, size, 0, 0, v->n);
+       if (isl_val_is_zero(v))
+               memset(chunks, 0, size);
+
+       return 0;
+}