Add: Circular byte buffer implementation

.editorconfig

@@ -0,0 +1,18 @@
+# editorconfig.org
+
+root = true
+
+[*]
+charset = utf-8
+end_of_line = lf
+indent_size = 4
+indent_style = space
+insert_final_newline = true
+trim_trailing_whitespace = true
+
+[*.{cpp,C,hpp,c,h}]
+indent_size = 4
+indent_style = space
+
+[*.md]
+trim_trailing_whitespace = true

.gitignore

@@ -50,3 +50,5 @@ modules.order
 Module.symvers
 Mkfile.old
 dkms.conf
+
+.vscode

circular-byte-buffer.c

@@ -0,0 +1,92 @@
+/******************************************************************************
+
+                  Copyright (c) 2017 Siddharth Chandrasekaran
+
+  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.
+
+    Author : Siddharth Chandrasekaran
+    Email  : siddharth@embedjournal.com
+    Date   : Sun Aug  5 09:42:31 IST 2017
+
+******************************************************************************/
+
+#include "circular-byte-buffer.h"
+
+int circ_bbuf_push(circ_bbuf_t *c, uint8_t data)
+{
+    int next;
+
+    next = c->head + 1;  // next is where head will point to after this write.
+    if (next >= c->maxlen)
+        next = 0;
+
+    if (next == c->tail)  // if the head + 1 == tail, circular buffer is full
+        return -1;
+
+    c->buffer[c->head] = data;  // Load data and then move
+    c->head = next;             // head to next data offset.
+    return 0;  // return success to indicate successful push.
+}
+
+int circ_bbuf_pop(circ_bbuf_t *c, uint8_t *data)
+{
+    int next;
+
+    if (c->head == c->tail)  // if the head == tail, we don't have any data
+        return -1;
+
+    next = c->tail + 1;  // next is where tail will point to after this read.
+    if(next >= c->maxlen)
+        next = 0;
+
+    *data = c->buffer[c->tail];  // Read data and then move
+    c->tail = next;              // tail to next offset.
+    return 0;  // return success to indicate successful push.
+}
+
+#ifdef C_UTILS_TESTING
+/* To test this module,
+ * $ gcc -Wall -DC_UTILS_TESTING circular-byte-buffer.c
+ * $ ./a.out
+*/
+
+CIRC_BBUF_DEF(my_circ_buf, 32);
+
+#include <stdio.h>
+
+int main()
+{
+    uint8_t out_data=0, in_data = 0x55;
+
+    if (circ_bbuf_push(&my_circ_buf, in_data)) {
+        printf("Out of space in CB\n");
+        return -1;
+    }
+
+    if (circ_bbuf_pop(&my_circ_buf, &out_data)) {
+        printf("CB is empty\n");
+        return -1;
+    }
+
+    printf("Push: 0x%x\n", in_data);
+    printf("Pop:  0x%x\n", out_data);
+    return 0;
+}
+
+#endif

circular-byte-buffer.h

@@ -0,0 +1,65 @@
+/******************************************************************************
+
+                  Copyright (c) 2017 Siddharth Chandrasekaran
+
+  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.
+
+    Author : Siddharth Chandrasekaran
+    Email  : siddharth@embedjournal.com
+    Date   : Sun Aug  5 09:42:31 IST 2017
+
+******************************************************************************/
+#ifndef __CIRCULAR_BYTE_BUFFER_H_
+#define __CIRCULAR_BYTE_BUFFER_H_
+
+#include <stdint.h>
+
+typedef struct {
+    uint8_t * const buffer;
+    int head;
+    int tail;
+    const int maxlen;
+} circ_bbuf_t;
+
+#define CIRC_BBUF_DEF(x,y)                \
+    uint8_t x##_data_space[y];            \
+    circ_bbuf_t x = {                     \
+        .buffer = x##_data_space,         \
+        .head = 0,                        \
+        .tail = 0,                        \
+        .maxlen = y                       \
+    }
+
+/*
+ * Method: circ_buf_pop
+ * Returns:
+ *  0 - Success
+ * -1 - Empty
+ */
+int circ_bbuf_pop(circ_bbuf_t *c, uint8_t *data);
+
+/*
+ * Method: circ_buf_push
+ * Returns:
+ *  0 - Success
+ * -1 - Out of space
+ */
+int circ_bbuf_push(circ_bbuf_t *c, uint8_t data);
+
+#endif /* __CIRCULAR_BYTE_BUFFER_H_ */