add comments

git-svn-id: https://svn.r-project.org/R/trunk@87895 00db46b3-68df-0310-9c12-caf00c1e9a41

Author: ripley

src/main/sort.c

@@ -83,6 +83,7 @@ static int scmp(SEXP x, SEXP y, Rboolean nalast)
 }
 
 #define R_INT_MIN 1 + INT_MIN //INT_MIN is NA_INTEGER
+// API: in Rinternals.h
 Rboolean isUnsorted(SEXP x, Rboolean strictly)
 {
     R_xlen_t n, i;
@@ -630,6 +631,7 @@ static void ssort2(SEXP *x, R_xlen_t n, Rboolean decreasing)
 }
 
 /* The meat of sort.int() */
+// Used in envir.c library/utils/src/io.c
 void sortVector(SEXP s, Rboolean decreasing)
 {
     R_xlen_t n = XLENGTH(s);
@@ -1118,6 +1120,7 @@ GREATER_2_SUB_DEF(intdbl2greater,    int, double, icmp, rcmp)
  * to the API */
 
 // Usage:  R_orderVector(indx, n,  Rf_lang2(x,y),  nalast, decreasing)
+// API
 void R_orderVector(int *indx, // must be pre-allocated to length >= n
 		   int n,
 		   SEXP arglist, // <- e.g.  Rf_lang2(x,y)
@@ -1130,6 +1133,7 @@ void R_orderVector(int *indx, // must be pre-allocated to length >= n
 }
 
 // Fast version of 1-argument case of R_orderVector()
+// API
 void R_orderVector1(int *indx, int n, SEXP x,
 		    Rboolean nalast, Rboolean decreasing)
 {
@@ -1143,6 +1147,7 @@ void R_orderVector1(int *indx, int n, SEXP x,
    Also used by do_options and  ../gnuwin32/extra.c
    Called with rho != R_NilValue only from do_rank, when NAs are not involved.
  */
+// used in envir.c options.c library/utils/src/windows/registry.c
 attribute_hidden void
 orderVector1(int *indx, int n, SEXP key, Rboolean nalast, Rboolean decreasing,
 	     SEXP rho)