C++ (Cpp) usb_disk_prepare_partial_buffer примеры использования

Пример #1

Файл: usb_disk.cpp Проект: earl-colby-pottinger/CRAM

static status_t
usb_disk_write(void *cookie, off_t position, const void *buffer,
	size_t *length)
{
	if (buffer == NULL || length == NULL)
		return B_BAD_VALUE;

	TRACE("write(%lld, %ld)\n", position, *length);
	device_lun *lun = (device_lun *)cookie;
	disk_device *device = lun->device;
	mutex_lock(&device->lock);
	if (device->removed) {
		*length = 0;
		mutex_unlock(&device->lock);
		return B_DEV_NOT_READY;
	}

	status_t result = B_ERROR;
	uint32 blockPosition = 0;
	uint16 blockCount = 0;
	bool needsPartial = usb_disk_needs_partial_buffer(lun, position,
		*length, blockPosition, blockCount);
	if (needsPartial) {
		void *partialBuffer = NULL;
		void *blockBuffer = NULL;
		result = usb_disk_prepare_partial_buffer(lun, position, *length,
			partialBuffer, blockBuffer, blockPosition, blockCount);
		if (result == B_OK) {
			memcpy(partialBuffer, buffer, *length);
			size_t blockLength = blockCount * lun->block_size;
			result = usb_disk_block_write(lun, blockPosition, blockCount,
				blockBuffer, &blockLength);
			free(blockBuffer);
		}
	} else {
		result = usb_disk_block_write(lun, blockPosition, blockCount,
			(void *)buffer, length);
	}

	mutex_unlock(&device->lock);
	if (result == B_OK) {
		TRACE("write successful with %ld bytes\n", *length);
		return B_OK;
	}

	*length = 0;
	TRACE_ALWAYS("write fails with 0x%08lx\n", result);
	return result;
}

Пример #2

Файл: usb_disk.cpp Проект: DonCN/haiku

static status_t
usb_disk_read(void *cookie, off_t position, void *buffer, size_t *length)
{
	if (buffer == NULL || length == NULL)
		return B_BAD_VALUE;

	TRACE("read(%" B_PRIdOFF ", %ld)\n", position, *length);
	device_lun *lun = (device_lun *)cookie;
	disk_device *device = lun->device;
	mutex_lock(&device->lock);
	if (device->removed) {
		*length = 0;
		mutex_unlock(&device->lock);
		return B_DEV_NOT_READY;
	}

	status_t result = B_ERROR;
	uint32 blockPosition = 0;
	uint16 blockCount = 0;
	bool needsPartial = usb_disk_needs_partial_buffer(lun, position, *length,
		blockPosition, blockCount);
	if (needsPartial) {
		void *partialBuffer = NULL;
		void *blockBuffer = NULL;
		result = usb_disk_prepare_partial_buffer(lun, position, *length,
			partialBuffer, blockBuffer, blockPosition, blockCount);
		if (result == B_OK) {
			memcpy(buffer, partialBuffer, *length);
			free(blockBuffer);
		}
	} else {
		result = usb_disk_block_read(lun, blockPosition, blockCount, buffer,
			length);
	}

	mutex_unlock(&device->lock);
	if (result == B_OK) {
		TRACE("read successful with %ld bytes\n", *length);
		return B_OK;
	}

	*length = 0;
	TRACE_ALWAYS("read failed: %s\n", strerror(result));
	return result;
}