1 files changed, 93 insertions, 0 deletions
diff --git a/src/stateful.c b/src/stateful.c
new file mode 100644
index 0000000..501db45
--- /dev/null
+++ b/src/stateful.c
@@ -0,0 +1,93 @@
+/*
+ * Copyright (C) 2012 Jamie Bullock
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to
+ * deal in the Software without restriction, including without limitation the
+ * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
+ * sell copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+ * IN THE SOFTWARE.
+ *
+ */
+
+/* stateful.c: declares functions that extract features that require stateful data to be retained between frames */
+
+#include "../xtract/xtract_stateful.h"
+#include "../xtract/libxtract.h"
+
+#include "c-ringbuf/ringbuf.h"
+
+#include <stdlib.h>
+#include <stdio.h>
+#include <float.h>
+
+struct xtract_last_n_state_
+{
+    ringbuf_t ringbuf;
+};
+
+
+xtract_last_n_state *xtract_last_n_state_new(size_t N)
+{
+    xtract_last_n_state *last_n_state = malloc(sizeof(xtract_last_n_state));
+    
+    if (last_n_state == NULL)
+    {
+        perror("could not allocate memory for xtract_last_n_state");
+        return NULL;
+    }
+    
+    last_n_state->ringbuf = ringbuf_new(N * sizeof(double));
+    
+    if (last_n_state->ringbuf)
+    {
+        perror("could not allocate memory for xtract_last_n_state->ringbuf");
+    }
+        
+    return last_n_state;
+}
+
+void xtract_last_n_state_delete(xtract_last_n_state *last_n_state)
+{
+    ringbuf_free(&last_n_state->ringbuf);
+    free(last_n_state);
+}
+
+int xtract_last_n(const xtract_last_n_state *state, const double *data, const int N, const void *argv, double *result)
+{
+    double *current = (double *)argv;
+    size_t N_bytes = N * sizeof(double);
+    
+    if (N_bytes != ringbuf_capacity(state->ringbuf))
+    {
+        fprintf(stderr, "libxtract: error: xtract_last_n(): inconsitent size");
+        return XTRACT_BAD_STATE;
+    }
+    
+    ringbuf_memcpy_into(state->ringbuf, current, sizeof(double));
+    size_t used = ringbuf_bytes_used(state->ringbuf);
+    ringbuf_memcpy_from(result, state->ringbuf, used, false);
+    
+    if (used < N_bytes)
+    {
+        /* zero pad */
+        for (size_t n = used / sizeof(double); n < N; ++n)
+        {
+            result[n] = 0.0;
+        }
+    }
+    
+    return XTRACT_SUCCESS;
+}
+