Added the interface specification for windowing.

There is no change in the implementation. The nWindows parameter
is currently ignored.

median.c

diff --git a/median.c b/median.c
index e47bb61..a2062a4 100644
--- a/median.c
+++ b/median.c
@@ -23,7 +23,7 @@
   size_t occupancy;       // Number of occupants for this buffer.
   unsigned char data[0];  // Start of the data block, cast as unsigned char.
   median_data_t
-      median_data[0];  // The data for this buffer cast as median_data_t.
+     median_data[0];      // The data for this buffer cast as median_data_t.
 };
 
 // ----------------------------------------------------------------------------
@@ -318,7 +318,9 @@
 // ----------------------------------------------------------------------------
 // Suggest the size of the buffer needed for a fixed epsilon and maxN.
 // ----------------------------------------------------------------------------
-median_error_t median_suggest_buffer_size(double epsilon, size_t maxN,
+median_error_t median_suggest_buffer_size(double epsilon,
+                                          size_t maxN,
+                                          size_t nWindows,
                                           size_t *suggested_size) {
   // First check for sane parameters.
 
@@ -374,14 +376,14 @@
 // Initialize an allocated buffer.
 // ----------------------------------------------------------------------------
 median_error_t median_init_buffer(void *buffer, size_t buffer_size,
-                                  double epsilon, size_t maxN,
+                                  double epsilon, size_t maxN, size_t nWindows,
                                   median_buffer_t *initialized_buffer) {
   // Initialize.
   size_t expectedSize = 0;
   median_error_t error = MEDIAN_OK;
 
   // First run median_suggest_buffer_size
-  if ((error = median_suggest_buffer_size(epsilon, maxN, &expectedSize)) !=
+  if ((error = median_suggest_buffer_size(epsilon, maxN, nWindows, &expectedSize)) !=
       MEDIAN_OK)
     return error;
   // Ensure that the buffer is large enough.

median.h

diff --git a/median.h b/median.h
index d4a83a2..0b1ceba 100644
--- a/median.h
+++ b/median.h
@@ -55,15 +55,23 @@
 // The default size of the largest possible dataset.
 static const size_t MEDIAN_MAX_N_DEFAULT = 1024 * 1024 * 1024;  // 1G.
 
+static const size_t N_WINDOWS_DEFAULT = 1;
+
 // This routine returns a suggested size for a buffer to hold all the
 // state needed for a median calculation. Here epsilon is the permissible error.
 // maxN is the largest dataset that we anticipate. If maxN is set to
 // MEDIAN_MAX_N_UNKNOWN (or zero), then we assume MEDIAN_MAX_N_DEFAULT to be the
-// value of maxN. The value return parameter is conventionally the last one. In
+// value of maxN.
+// nWindows is the number of concurrently active windows. The default value
+// for nWindows is 1 (aka N_WINDOWS_DEFAULT). If no windowing is desired,
+// N_WINDOWS_DEFAULT should be used.
+// The value return parameter is conventionally the last one. In
 // this case, it contains the suggested_size of the buffer, assuming that the
 // return value is MEDIAN_ERROR_OK. In all reasonable calls, the returned value
 // will be MEDIAN_ERROR_OK.
-median_error_t median_suggest_buffer_size(double epsilon, size_t maxN,
+median_error_t median_suggest_buffer_size(double epsilon,
+                                          size_t maxN,
+                                          size_t nWindows,
                                           size_t *suggested_size);
 // Suggest a size of the buffer for scratch space. This is needed
 // so that the buffer is not corrupted by the output and merge steps.
@@ -89,7 +97,7 @@
 // is initialized. In all reasonable calls, the returned value will be
 // MEDIAN_ERROR_OK.
 median_error_t median_init_buffer(void *buffer, size_t buffer_size,
-                                  double epsilon, size_t maxN,
+                                  double epsilon, size_t maxN, size_t nWindows,
                                   median_buffer_t *initialized_buffer);
 // This frees up any internal resource consumed with the buffer, including
 // mutex locks and other provisioned resources.

median.main.c

diff --git a/median.main.c b/median.main.c
index 15cbb36..1aca550 100644
--- a/median.main.c
+++ b/median.main.c
@@ -15,11 +15,11 @@
 
   // Allocate the buffer of the required size. And then
   // initialize it (median_init_buffer).
-  assert(median_suggest_buffer_size(.001, TEST_SIZE, &n) == MEDIAN_OK);
+  assert(median_suggest_buffer_size(.001, TEST_SIZE, N_WINDOWS_DEFAULT, &n) == MEDIAN_OK);
   void* b = malloc(n);
   assert(b);
   median_buffer_t buf;
-  assert(median_init_buffer(b, n, .001, TEST_SIZE, &buf) == MEDIAN_OK);
+  assert(median_init_buffer(b, n, .001, TEST_SIZE, N_WINDOWS_DEFAULT, &buf) == MEDIAN_OK);
 
   // Initialize the spare buffer.
   assert(median_suggest_scratch_buffer_size(buf, &n) == MEDIAN_OK);