changer.c

这是一个同样来自贝尔实验室的和UNIX有着渊源的操作系统, 其简洁的设计和实现易于我们学习和理解

#include <u.h>
#include <libc.h>

#include "scsireq.h"

long
SReinitialise(ScsiReq *rp)
{
	uchar cmd[6];

	memset(cmd, 0, sizeof(cmd));
	cmd[0] = ScmdEInitialise;
	rp->cmd.p = cmd;
	rp->cmd.count = sizeof(cmd);
	rp->data.p = cmd;
	rp->data.count = 0;
	rp->data.write = 1;
	return SRrequest(rp);
}

long
SRmmove(ScsiReq *rp, int transport, int source, int destination, int invert)
{
	uchar cmd[12];

	memset(cmd, 0, sizeof(cmd));
	cmd[0] = ScmdMMove;
	cmd[2] = transport>>8;
	cmd[3] = transport;
	cmd[4] = source>>8;
	cmd[5] = source;
	cmd[6] = destination>>8;
	cmd[7] = destination;
	cmd[10] = invert & 0x01;
	rp->cmd.p = cmd;
	rp->cmd.count = sizeof(cmd);
	rp->data.p = cmd;
	rp->data.count = 0;
	rp->data.write = 1;
	return SRrequest(rp);
}

long
SRestatus(ScsiReq *rp, uchar type, uchar *list, int nbytes)
{
	uchar cmd[12];

	memset(cmd, 0, sizeof(cmd));
	cmd[0] = ScmdEStatus;
	cmd[1] = type & 0x07;
	cmd[4] = 0xFF;
	cmd[5] = 0xFF;
	cmd[7] = nbytes>>16;
	cmd[8] = nbytes>>8;
	cmd[9] = nbytes;
	rp->cmd.p = cmd;
	rp->cmd.count = sizeof(cmd);
	rp->data.p = list;
	rp->data.count = nbytes;
	rp->data.write = 0;
	return SRrequest(rp);
}