ddf_io.c

一个简单的小型操作系统

/*****************************************************************************
 * 
 * Module       : ddf_io.c
 * Description  : interface to the low level drivers. io conform
 *                with DDF 0.01 specification.
 * OS           : SLOS 0.09
 * Platform     : e7t
 * History      :
 *
 * 20th November 2001 Andrew N. Sloss
 * - created io.c from the DDF 0.01 test program
 *
 *****************************************************************************/

/*****************************************************************************
 * IMPORT 
 *****************************************************************************/

#include "../e7t/devices/ddf_tree.h"

/*****************************************************************************
 * ROUTINES 
 *****************************************************************************/

/* -- ioInitalizeDrivers ------------------------------------------------------
 *
 * Description  : initializes all the device driver in the device_treestr
 *
 * Parameters   : DDF does not take any parameter
 * Return       : none...
 * Notes        :
 * 
 */

void ioInitializeDrivers(void) 
{
device_treestr *driver = devices;

  while (*driver->init != 0) 
  {
  driver->init();
  driver ++;
  }
}

/* -- ioOpenDriver ------------------------------------------------------------
 * 
 * Description  : open a driver for access
 *
 * Parameters   : int *id - pointer the id 
 *              : unsigned major - major device i.e. DEVICE_SERIAL_E7T
 *              : unsigned minor - minor device i.e. COM1
 * Return       : device_treestr * ptr
 * Notes        :
 *
 */ 

device_treestr *ioOpenDriver(int *id,unsigned int major,unsigned int minor) 
{
device_treestr *driver = devices;

  while (*driver->init != 0) 
  {
  *id = driver->open(major,minor);  	

    if (*id>0) 
    {
    return driver;
    }

  driver ++;
  }

return (device_treestr *)0; /* no driver found */
}

/* -- ioCloseDriver -----------------------------------------------------------
 * 
 * Description  : close a driver for access
 *
 * Parameters   : device_treestr * - pointer to device node. 
 *              : UID id - id of particular device
 * Return       : int 
 * Notes        : 
 *
 */ 

int ioCloseDriver(device_treestr *d, UID id) 
{
  if (d==(device_treestr *)0) {return -2;}

return d->close(id);
}

/* -- ioBitWrite --------------------------------------------------------------
 * 
 * Description  : write a bit to the device
 *
 * Parameters   : device_treestr * - pointer to device node. 
 *              : UID id - id of particular device
 *              : BYTE bit - only least significant used
 * Return       : none...
 * Notes        : 
 *
 */ 

void ioWriteBit(device_treestr *d,UID id,BYTE bit) 
{
  if (d==(device_treestr *)0) {return;}

d->write.bit(id,bit);
}

/* -- ioBitRead ---------------------------------------------------------------
 * 
 * Description  : read a bit to the device
 *
 * Parameters   : device_treestr * - pointer to device node. 
 *              : UID id - id of particular device
 *              : BYTE bit - only least significant used
 * Return       : BYTE if = 255 then error
 * Notes        : 
 *
 */ 

BYTE ioReadBit(device_treestr *d,UID id) 
{
  if (d==(device_treestr *)0) {return 255;}

  return d->read.bit(id);
}

/* -- ioWriteByte -------------------------------------------------------------
 * 
 * Description  : write a byte to the device
 *
 * Parameters   : device_treestr * - pointer to device node. 
 *              : UID id - id of particular device
 *              : BYTE byte - byte to be written
 * Return       : none...
 * Notes        : 
 *
 */ 

void ioWriteByte(device_treestr *d,UID id,BYTE byte) 
{
  if (d==(device_treestr *)0) {return;}

d->write.byte(id,byte);
}

/* -- ioReadByte --------------------------------------------------------------
 * 
 * Description  : read a byte to the device
 *
 * Parameters   : device_treestr * - pointer to device node. 
 *              : UID id - id of particular device
 * Return       : BYTE if = 255 then error
 * Notes        : 
 *
 */ 

BYTE ioReadByte(device_treestr *d,UID id) 
{
  if (d==(device_treestr *)0) {return 255;}

return d->read.byte(id);
}

/* -- ioWriteBlock ------------------------------------------------------------
 * 
 * Description  : write a block to the device
 *
 * Parameters   : device_treestr * - pointer to device node. 
 *              : UID id - id of particular device
 *              : block_data_t * block
 * Return       : none...
 * Notes        : 
 *
 */ 

void ioWriteBlock(device_treestr *d,UID id, block_data_t *block) 
{
  if (d==(device_treestr *)0) {return;}

d->write.block(id,block);
}

/* -- ioReadBlock -------------------------------------------------------------
 * 
 * Description  : read a block from a device
 *
 * Parameters   : device_treestr * - pointer to device node. 
 *              : UID id - id of particular device
 * Return       : block_data_t *
 * Notes        : 
 *
 */ 

block_data_t *ioReadBlock (device_treestr *d,UID id) 
{
  if (d==(device_treestr *)0) {return 0;}

return d->read.block(id);
}