From 74d7ad2704011d724b41e5dcee7f7c05e90412cb Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?V=C3=ADtor=20Santos=20Costa?= <vsc@dcc.fc.up.pt>
Date: Wed, 14 Mar 2012 11:08:28 +0000
Subject: [PATCH] extend interface to copy fast lists of integers or floats.

---
 C/c_interface.c        | 104 +++++++++++++++++++++++++++++++++++++----
 docs/yap.tex           |  16 ++++++-
 include/YapInterface.h |   4 ++
 3 files changed, 113 insertions(+), 11 deletions(-)

diff --git a/C/c_interface.c b/C/c_interface.c
index 610dc9c00..d9d773f88 100644
--- a/C/c_interface.c
+++ b/C/c_interface.c
@@ -442,6 +442,9 @@ X_API void    STD_PROTO(YAP_FreeSpaceFromYap,(void *));
 X_API int     STD_PROTO(YAP_StringToBuffer, (Term, char *, unsigned int));
 X_API Term    STD_PROTO(YAP_ReadBuffer, (char *,Term *));
 X_API Term    STD_PROTO(YAP_FloatsToList, (double *, size_t));
+X_API Int     STD_PROTO(YAP_ListToFloats, (Term, double *, size_t));
+X_API Term    STD_PROTO(YAP_IntsToList, (Int *, size_t));
+X_API Int     STD_PROTO(YAP_ListToInts, (Term, Int *, size_t));
 X_API Term    STD_PROTO(YAP_BufferToString, (char *));
 X_API Term    STD_PROTO(YAP_NBufferToString, (char *, size_t));
 X_API Term    STD_PROTO(YAP_WideBufferToString, (wchar_t *));
@@ -3594,6 +3597,89 @@ YAP_FloatsToList(double *dblp, size_t sz)
   return t;
 }
 
+X_API Int
+YAP_ListToFloats(Term t, double *dblp, size_t sz)
+{
+  size_t i = 0;
+
+  t = Deref(t);
+  do {
+    Term hd;
+    if (IsVarTerm(t))
+	return -1;
+    if (t == TermNil)
+      return i;
+    if (!IsPairTerm(t))
+      return -1;
+    hd = HeadOfTerm(t);
+    if (!IsFloatTerm(hd))
+      return -1;
+    dblp[i++] = FloatOfTerm(hd);
+    if (i == sz)
+      return sz;
+    t = TailOfTerm(t);
+  } while (TRUE);
+}
+
+X_API Term
+YAP_IntsToList(Int *dblp, size_t sz)
+{
+  CACHE_REGS
+  Term t;
+  CELL *oldH;
+  BACKUP_H();
+
+  if (!sz)
+    return TermNil;
+  while (ASP-1024 < H + sz*3) {
+    if ((CELL *)dblp > H0 && (CELL *)dblp < H) {
+      /* we are in trouble */
+      LOCAL_OpenArray =  (CELL *)dblp;
+    }
+    if (!dogc( 0, NULL PASS_REGS )) {
+      RECOVER_H();
+      return 0L;
+    }
+    dblp = (Int *)LOCAL_OpenArray;
+    LOCAL_OpenArray = NULL;
+  }
+  t = AbsPair(H);
+  while (sz) {
+    oldH = H;
+    H +=2;
+    oldH[0] = MkIntegerTerm(*dblp++);
+    oldH[1] = AbsPair(H);
+    sz--;
+  }
+  oldH[1] = TermNil;
+  RECOVER_H();
+  return t;
+}
+
+X_API Int
+YAP_ListToInts(Term t, Int *dblp, size_t sz)
+{
+  size_t i = 0;
+
+  t = Deref(t);
+  do {
+    Term hd;
+    if (IsVarTerm(t))
+	return -1;
+    if (t == TermNil)
+      return i;
+    if (!IsPairTerm(t))
+      return -1;
+    hd = HeadOfTerm(t);
+    if (!IsIntTerm(hd))
+      return -1;
+    dblp[i++] = IntOfTerm(hd);
+    if (i == sz)
+      return sz;
+    t = TailOfTerm(t);
+  } while (TRUE);
+}
+
 X_API Term
 YAP_OpenList(int n)
 {
@@ -3975,16 +4061,14 @@ Term YAP_BPROLOG_curr_toam_status;
 
 Int
 YAP_ListLength(Term t) {
-  Int l = 0;
-  while (TRUE) {
-    if (IsVarTerm(t)) return -1;
-    if (t == TermNil)
-      return l;
-    if (!IsPairTerm(t)) 
-      return -1;
-    l++;
-    t = TailOfTerm(t);
-  }
+  Term *aux;
+
+  Int n = Yap_SkipList(&t, &aux);
+  if (IsVarTerm(*aux))
+    return -1;
+  if (*aux == TermNil)
+    return n;
+  return -1;
 }
 
 Int
diff --git a/docs/yap.tex b/docs/yap.tex
index 2d3730475..5709a446c 100644
--- a/docs/yap.tex
+++ b/docs/yap.tex
@@ -16536,13 +16536,27 @@ The user-provided string must include a terminating null
 character. Syntax errors will cause returning @code{FALSE} and binding
 @var{error} to a Prolog term.
 
+@findex YAP_IntsToList (C-Interface function)
 @findex YAP_FloatsToList (C-Interface function)
 These C-interface functions are useful when converting chunks of data to Prolog:
 @example
       YAP_Term YAP_FloatsToList(double *@var{buf},size_t @var{sz})
+      YAP_Term YAP_IntsToList(YAP_Int *@var{buf},size_t @var{sz})
 @end example
 @noindent
-Notice that they are unsafe, and may call the garbage collector.
+Notice that they are unsafe, and may call the garbage collector. They
+return 0 on error.
+
+@findex YAP_ListToInts (C-Interface function)
+@findex YAP_ToListFloats (C-Interface function)
+These C-interface functions are useful when converting Prolog lists to arrays:
+@example
+      YAP_Int YAP_IntsToList(YAP_Term t, YAP_Int *@var{buf},size_t @var{sz})
+      YAP_Int YAP_FloatsToList(YAP_Term t, double *@var{buf},size_t @var{sz})
+@end example
+@noindent
+They return the number of integers scanned, up to a maximum of @t{sz},
+and @t{-1} on error.
 
 @node Memory Allocation, Controlling Streams, Manipulating Strings, C-Interface
 @section Memory Allocation
diff --git a/include/YapInterface.h b/include/YapInterface.h
index 371863aba..f58bfd159 100644
--- a/include/YapInterface.h
+++ b/include/YapInterface.h
@@ -357,6 +357,10 @@ extern X_API void PROTO(YAP_PutValue,(YAP_Atom, YAP_Term));
 extern X_API YAP_Term PROTO(YAP_GetValue,(YAP_Atom));
 
 extern X_API YAP_Term PROTO(YAP_FloatsToList,(YAP_Float *, size_t));
+extern X_API YAP_Int  PROTO(YAP_ListToFloats,(YAP_Term, YAP_Float *, size_t));
+
+extern X_API YAP_Term PROTO(YAP_IntsToList,(YAP_Int *, size_t));
+extern X_API YAP_Int  PROTO(YAP_ListToInts,(YAP_Term, YAP_Int *, size_t));
 
 /*  int StringToBuffer(YAP_Term,char *,unsigned int) */
 extern X_API int PROTO(YAP_StringToBuffer,(YAP_Term,char *,unsigned int));