ffi: new carray-buf-sync function.

* ffi.c (carray_buf_sync): New function.
(ffi_init): carray-buf-sync intrinsic registered.

* ffi.h (carray_buf_sync): Declared.

* txr.1: Documented.

3 files changed, 42 insertions, 0 deletions

diff --git a/ffi.c b/ffi.c
index 6dfd663c..5624b9dd 100644
--- a/ffi.c
+++ b/ffi.c
@@ -2619,6 +2619,19 @@ val carray_buf(val buf, val type)
   return make_carray(type, data, nelem, buf);
 }
 
+val carray_buf_sync(val carray)
+{
+  val self = lit("carray-buf-sync");
+  struct carray *scry = carray_struct_checked(carray);
+  val buf = scry->ref;
+  mem_t *data = buf_get(buf, self);
+  cnum blen = c_num(length_buf(buf));
+  struct txr_ffi_type *tft = ffi_type_struct(scry->eltype);
+  scry->nelem = blen / tft->size;
+  scry->data = data;
+  return buf;
+}
+
 val carray_cptr(val cptr, val type, val len)
 {
   mem_t *data = cptr_get(cptr);
@@ -2756,6 +2769,7 @@ void ffi_init(void)
   reg_fun(intern(lit("carray-vec"), user_package), func_n3o(carray_vec, 2));
   reg_fun(intern(lit("carray-blank"), user_package), func_n2(carray_blank));
   reg_fun(intern(lit("carray-buf"), user_package), func_n2(carray_buf));
+  reg_fun(intern(lit("carray-buf-sync"), user_package), func_n1(carray_buf_sync));
   reg_fun(intern(lit("carray-cptr"), user_package), func_n3o(carray_cptr, 2));
   reg_fun(intern(lit("vec-carray"), user_package), func_n2o(vec_carray, 1));
   reg_fun(intern(lit("list-carray"), user_package), func_n2o(list_carray, 1));
diff --git a/ffi.h b/ffi.h
index 59a3ec30..5545126e 100644
--- a/ffi.h
+++ b/ffi.h
@@ -74,6 +74,7 @@ mem_t *carray_get(val carray, val type, val self);
 val carray_vec(val vec, val type, val null_term_p);
 val carray_blank(val nelem, val type);
 val carray_buf(val buf, val type);
+val carray_buf_sync(val carray);
 val carray_cptr(val cptr, val type, val len);
 val vec_carray(val carray, val null_term_p);
 val list_carray(val carray, val null_term_p);
diff --git a/txr.1 b/txr.1
index 4de55690..df361b52 100644
--- a/txr.1
+++ b/txr.1
@@ -54968,6 +54968,33 @@ type, the calculated number of elements is rounded down. The trailing portion
 of the buffer corresponding to the division remainder, being insufficient
 to constitute a whole array element, is excluded from the array view.
 
+.coNP Function @ carray-buf-sync
+.synb
+.mets (carray-buf-sync << carray )
+.syne
+.desc
+The
+.code carray-buf-sync
+function requires
+.meta carray
+to be a
+.code carray
+object which refers to a
+.code buf
+object for its storage. Such objects are created by the function
+.codn carray-buf .
+
+The
+.code carray-buf-sync
+function retrieves and returns the buffer object associated with
+.meta carray
+and at the same time also updates the internal properties of
+.meta carray
+using the current information: the pointer to the data, and the
+length of
+.meta carray
+are altered to reflect the current state of the buffer.
+
 .coNP Function @ carray-cptr
 .synb
 .mets (carray-cptr < cptr < type <> [ length ])