1 files changed, 70 insertions, 0 deletions
diff --git a/buffers.h b/buffers.h
new file mode 100644
index 0000000..19edd2d
--- /dev/null
+++ b/buffers.h
@@ -0,0 +1,70 @@
+/* This defines common buffer code for whole library.
+ * It is preprocessor generated code.
+ * Preprocessor variables chose different implementations. But final
+ * implementation is only few lines of code. This way it is included directly
+ * to code.
+ */
+#ifndef _IOE_BUFFERS_H_
+#define _IOE_BUFFERS_H_
+
+// Define new buffer
+#define IOEBUFFER(name, size) struct { \
+        uint8_t rindex, windex; \
+        uint8_t data[size]; \
+    } name;
+
+#define IOEBUFFER_INIT(name, size) { \
+    name.windex = size - 1; \
+    name.rindex = size - 1; \
+    }
+
+#define IOEBUFFER_MODE_BLOCK 0
+#define IOEBUFFER_MODE_OVERWRITE 1
+#define IOEBUFFER_MODE_DROP 2
+// Add data to buffer. If buffer is full then behavior is defined by selected mode.
+#define IOEBUFFER_PUT(name, size, data, mode) \
+    if (mode == IOEBUFFER_MODE_BLOCK) { \
+        if (name.windex == 0) { \
+            while (name.rindex == size - 1); \
+        } else { \
+            while (name.rindex == name.windex - 1); \
+        } \
+    } \
+    name.data[name.windex] = data; \
+    if (mode != IOEBUFFER_MODE_DROP || \
+            (name.windex == 0 && name.rindex == size - 1) || \
+            (name.rindex + 1 == name.windex)) { \
+        if (name.windex == 0) \
+            name.windex = size - 1; \
+        else \
+            name.windex--; \
+    } \
+    if (mode == IOEBUFFER_MODE_OVERWRITE && name.windex == name.rindex) { \
+        if (name.windex == size - 1) \
+            name.windex = 0; \
+        else \
+            name.windex++; \
+    } else;
+
+// Get data from buffer and store it to variable
+#define IOEBUFFER_GET(name, size, variable) \
+    if (name.rindex != name.windex) { \
+        variable = name.data[name.rindex]; \
+        if (name.rindex == 0) \
+            name.rindex = size - 1; \
+        else \
+            name.rindex--; \
+    } else { \
+        variable = 0; \
+    }
+
+// Set count of buffered data to variable
+#define IOEBUFFER_CNT(name, size, variable) \
+    if (name.windex < name.rindex) \
+        variable = name.rindex - name.windex; \
+    else if (name.windex > name.rindex) \
+        variable = size - name.windex + name.rindex; \
+    else \
+        variable = 0;
+
+#endif /* _IOE_BUFFERS_H_ */