lib/bio/mem.c

/*
 * Copyright (c) 2009 Travis Geiselbrecht
 *
 * 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.
 */
#include <debug.h>
#include <string.h>
#include <stdlib.h>
#include <lib/bio.h>

#define LOCAL_TRACE 0

#define BLOCKSIZE 512

typedef struct mem_bdev {
	bdev_t dev; // base device

	void *ptr;
} mem_bdev_t;

static ssize_t mem_bdev_read(bdev_t *bdev, void *buf, off_t offset, size_t len)
{
	mem_bdev_t *mem = (mem_bdev_t *)bdev;

	LTRACEF("bdev %s, buf %p, offset %lld, len %zu\n", bdev->name, buf, offset, len);

	memcpy(buf, (uint8_t *)mem->ptr + offset, len);

	return len;
}

static ssize_t mem_bdev_read_block(struct bdev *bdev, void *buf, bnum_t block, uint count)
{
	mem_bdev_t *mem = (mem_bdev_t *)bdev;

	LTRACEF("bdev %s, buf %p, block %u, count %u\n", bdev->name, buf, block, count);

	memcpy(buf, (uint8_t *)mem->ptr + block * BLOCKSIZE, count * BLOCKSIZE);

	return count * BLOCKSIZE;
}

static ssize_t mem_bdev_write(bdev_t *bdev, const void *buf, off_t offset, size_t len)
{
	mem_bdev_t *mem = (mem_bdev_t *)bdev;

	LTRACEF("bdev %s, buf %p, offset %lld, len %zu\n", bdev->name, buf, offset, len);

	memcpy((uint8_t *)mem->ptr + offset, buf, len);

	return len;
}

static ssize_t mem_bdev_write_block(struct bdev *bdev, const void *buf, bnum_t block, uint count)
{
	mem_bdev_t *mem = (mem_bdev_t *)bdev;

	LTRACEF("bdev %s, buf %p, block %u, count %u\n", bdev->name, buf, block, count);

	memcpy((uint8_t *)mem->ptr + block * BLOCKSIZE, buf, count * BLOCKSIZE);

	return count * BLOCKSIZE;
}

int create_membdev(const char *name, void *ptr, size_t len)
{
	mem_bdev_t *mem = malloc(sizeof(mem_bdev_t));

	/* set up the base device */
	bio_initialize_bdev(&mem->dev, name, BLOCKSIZE, len / BLOCKSIZE);

	/* our bits */
	mem->ptr = ptr;
	mem->dev.read = mem_bdev_read;
	mem->dev.read_block = mem_bdev_read_block;
	mem->dev.write = mem_bdev_write;
	mem->dev.write_block = mem_bdev_write_block;

	/* register it */
	bio_register_device(&mem->dev);

	return 0;
}