ringbuffer: add a simple ringbuffer data structure

Signed-off-by: Sven Peter <sven@svenpeter.dev>

Makefile

@@ -49,6 +49,7 @@ OBJECTS := \
 	payload.o \
 	pmgr.o \
 	proxy.o \
+	ringbuffer.o \
 	smp.o \
 	start.o \
 	startup.o \

src/ringbuffer.c

@@ -0,0 +1,81 @@
+#include "ringbuffer.h"
+#include "malloc.h"
+#include "types.h"
+
+ringbuffer_t *ringbuffer_alloc(size_t len)
+{
+    ringbuffer_t *bfr = malloc(sizeof(*bfr));
+    if (!bfr)
+        return NULL;
+
+    bfr->buffer = malloc(len);
+    if (!bfr->buffer) {
+        free(bfr);
+        return NULL;
+    }
+
+    bfr->read = 0;
+    bfr->write = 0;
+    bfr->len = len;
+
+    return bfr;
+}
+
+void ringbuffer_free(ringbuffer_t *bfr)
+{
+    if (bfr)
+        free(bfr->buffer);
+    free(bfr);
+}
+
+size_t ringbuffer_read(u8 *target, size_t len, ringbuffer_t *bfr)
+{
+    size_t read;
+
+    for (read = 0; read < len; ++read) {
+        if (bfr->read == bfr->write)
+            break;
+
+        *target = bfr->buffer[bfr->read];
+        target++;
+
+        bfr->read++;
+        bfr->read %= bfr->len;
+    }
+
+    return read;
+}
+
+size_t ringbuffer_write(const u8 *src, size_t len, ringbuffer_t *bfr)
+{
+    size_t written;
+
+    for (written = 0; written < len; ++written) {
+        if (((bfr->write + 1) % bfr->len) == bfr->read)
+            break;
+
+        bfr->buffer[bfr->write] = *src;
+        src++;
+
+        bfr->write++;
+        bfr->write %= bfr->len;
+    }
+
+    return written;
+}
+
+size_t ringbuffer_get_used(ringbuffer_t *bfr)
+{
+    size_t read = bfr->read;
+    size_t write = bfr->write;
+
+    if (write < read)
+        write += bfr->len;
+
+    return write - read;
+}
+
+size_t ringbuffer_get_free(ringbuffer_t *bfr)
+{
+    return bfr->len - ringbuffer_get_used(bfr);
+}

src/ringbuffer.h

@@ -0,0 +1,22 @@
+#ifndef RINGBUFFER_H
+#define RINGBUFFER_H
+
+#include "types.h"
+
+typedef struct {
+    u8 *buffer;
+    size_t len;
+    size_t read;
+    size_t write;
+} ringbuffer_t;
+
+ringbuffer_t *ringbuffer_alloc(size_t len);
+void ringbuffer_free(ringbuffer_t *bfr);
+
+size_t ringbuffer_read(u8 *target, size_t len, ringbuffer_t *bfr);
+size_t ringbuffer_write(const u8 *src, size_t len, ringbuffer_t *bfr);
+
+size_t ringbuffer_get_used(ringbuffer_t *bfr);
+size_t ringbuffer_get_free(ringbuffer_t *bfr);
+
+#endif