kernel: ringbuffer

kernel-src/include/ringbuffer.h

@@ -0,0 +1,21 @@
+#ifndef _RINGBUFFER_H
+#define _RINGBUFFER_H
+
+#include <stddef.h>
+#include <stdint.h>
+
+typedef struct {
+	size_t size;
+	uintmax_t write;
+	uintmax_t read;
+	void *data;
+} ringbuffer_t;
+
+int ringbuffer_init(ringbuffer_t *ringbuffer, size_t size);
+void ringbuffer_destroy(ringbuffer_t *ringbuffer);
+size_t ringbuffer_read(ringbuffer_t* ringbuffer, void *buffer, size_t count);
+size_t ringbuffer_write(ringbuffer_t* ringbuffer, void *buffer, size_t count);
+
+#define RINGBUFFER_DATACOUNT(x) ((x)->write - (x)->read)
+
+#endif

kernel-src/lib/ringbuffer.c

@@ -0,0 +1,47 @@
+#include <ringbuffer.h>
+#include <kernel/vmm.h>
+#include <util.h>
+#include <errno.h>
+
+int ringbuffer_init(ringbuffer_t *ringbuffer, size_t size) {
+	ringbuffer->data = vmm_map(NULL, ROUND_UP(size, PAGE_SIZE), VMM_FLAGS_ALLOCATE, ARCH_MMU_FLAGS_WRITE | ARCH_MMU_FLAGS_READ | ARCH_MMU_FLAGS_NOEXEC, NULL);
+	if (ringbuffer->data == NULL)
+		return ENOMEM;
+
+	ringbuffer->size = size;
+	ringbuffer->write = 0;
+	ringbuffer->read = 0;
+	return 0;
+}
+
+void ringbuffer_destroy(ringbuffer_t *ringbuffer) {
+	vmm_unmap(ringbuffer->data, ROUND_UP(ringbuffer->size, PAGE_SIZE), 0);
+}
+
+size_t ringbuffer_read(ringbuffer_t* ringbuffer, void *buffer, size_t count) {
+	uint8_t *ptr = buffer;
+	size_t readc = 0;
+	for (; readc < count; ++readc) {
+		if (ringbuffer->read == ringbuffer->write)
+			break;
+
+		uintmax_t readoffset = ringbuffer->read % ringbuffer->size;
+		*ptr++ = *((uint8_t *)ringbuffer->data + readoffset);
+		++ringbuffer->read;
+	}
+	return readc;
+}
+
+size_t ringbuffer_write(ringbuffer_t* ringbuffer, void *buffer, size_t count) {
+	uint8_t *ptr = buffer;
+	size_t writec = 0;
+	for (;writec < count; ++writec) {
+		if (ringbuffer->write == ringbuffer->read + ringbuffer->size)
+			break;
+
+		uintmax_t writeoffset = ringbuffer->write % ringbuffer->size;
+		*((uint8_t *)ringbuffer->data + writeoffset) = *ptr++;
+		++ringbuffer->write;
+	}
+	return writec;
+}