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Annotation of Gnu-Mach/device/kmsg.c, revision 1.1

1.1     ! root        1: /* GNU Mach Kernel Message Device.
        !             2:    Copyright (C) 1998, 1999 Free Software Foundation, Inc.
        !             3:    Written by OKUJI Yoshinori.
        !             4: 
        !             5: This is free software; you can redistribute it and/or modify
        !             6: it under the terms of the GNU General Public License as published by
        !             7: the Free Software Foundation; either version 2, or (at your option)
        !             8: any later version.
        !             9: 
        !            10: This software is distributed in the hope that it will be useful,
        !            11: but WITHOUT ANY WARRANTY; without even the implied warranty of
        !            12: MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
        !            13: GNU General Public License for more details.
        !            14: 
        !            15: You should have received a copy of the GNU General Public License
        !            16: along with the software; see the file COPYING.  If not, write to
        !            17: the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.  */
        !            18: 
        !            19: /* Now kmsg provides stream interface, not random access methods.  */
        !            20: 
        !            21: #include <sys/types.h>
        !            22: #include <device/conf.h>
        !            23: #include <device/io_req.h>
        !            24: #include <mach/boolean.h>
        !            25: #include <kern/lock.h>
        !            26: #include <kmsg.h>
        !            27: 
        !            28: 
        !            29: #define KMSGBUFSIZE    (4096)  /* XXX */
        !            30: 
        !            31: /* Simple array for buffering messages */
        !            32: static char kmsg_buffer[KMSGBUFSIZE];
        !            33: /* Point to the offset to write */
        !            34: static int kmsg_write_offset;
        !            35: /* Point to the offset to read */
        !            36: static int kmsg_read_offset;
        !            37: /* I/O request queue for blocking read */
        !            38: static queue_head_t kmsg_read_queue;
        !            39: /* Used for exclusive access to the device */
        !            40: static int kmsg_in_use;
        !            41: /* Used for exclusive access to the routines */
        !            42: static simple_lock_data_t kmsg_lock;
        !            43: /* If already initialized or not  */
        !            44: static int kmsg_init_done = 0;
        !            45: 
        !            46: /* Kernel Message Initializer */
        !            47: static void
        !            48: kmsginit (void)
        !            49: {
        !            50:   kmsg_write_offset = 0;
        !            51:   kmsg_read_offset = 0;
        !            52:   queue_init (&kmsg_read_queue);
        !            53:   kmsg_in_use = 0;
        !            54:   simple_lock_init (&kmsg_lock);
        !            55: }
        !            56: 
        !            57: /* Kernel Message Open Handler */
        !            58: io_return_t
        !            59: kmsgopen (dev_t dev, int flag, io_req_t ior)
        !            60: {
        !            61:   simple_lock (&kmsg_lock);
        !            62:   if (kmsg_in_use)
        !            63:     {
        !            64:       simple_unlock (&kmsg_lock);
        !            65:       return D_ALREADY_OPEN;
        !            66:     }
        !            67:   
        !            68:   kmsg_in_use = 1;
        !            69: 
        !            70:   simple_unlock (&kmsg_lock);
        !            71:   return D_SUCCESS;
        !            72: }
        !            73: 
        !            74: /* Kernel Message Close Handler */
        !            75: io_return_t
        !            76: kmsgclose (dev_t dev, int flag)
        !            77: {
        !            78:   simple_lock (&kmsg_lock);
        !            79:   kmsg_in_use = 0;
        !            80:   
        !            81:   simple_unlock (&kmsg_lock);
        !            82:   return D_SUCCESS;
        !            83: }
        !            84: 
        !            85: static boolean_t kmsg_read_done (io_req_t ior);
        !            86: 
        !            87: /* Kernel Message Read Handler */
        !            88: io_return_t
        !            89: kmsgread (dev_t dev, io_req_t ior)
        !            90: {
        !            91:   int err;
        !            92:   int amt, len;
        !            93:   
        !            94:   err = device_read_alloc (ior, ior->io_count);
        !            95:   if (err != KERN_SUCCESS)
        !            96:     return err;
        !            97: 
        !            98:   simple_lock (&kmsg_lock);
        !            99:   if (kmsg_read_offset == kmsg_write_offset)
        !           100:     {
        !           101:       /* The queue is empty.  */
        !           102:       if (ior->io_mode & D_NOWAIT)
        !           103:        {
        !           104:          simple_unlock (&kmsg_lock);
        !           105:          return D_WOULD_BLOCK;
        !           106:        }
        !           107: 
        !           108:       ior->io_done = kmsg_read_done;
        !           109:       enqueue_tail (&kmsg_read_queue, ior);
        !           110:       simple_unlock (&kmsg_lock);
        !           111:       return D_IO_QUEUED;
        !           112:     }
        !           113: 
        !           114:   len = kmsg_write_offset - kmsg_read_offset;
        !           115:   if (len < 0)
        !           116:     len += KMSGBUFSIZE;
        !           117: 
        !           118:   amt = ior->io_count;
        !           119:   if (amt > len)
        !           120:     amt = len;
        !           121:   
        !           122:   if (kmsg_read_offset + amt <= KMSGBUFSIZE)
        !           123:     {
        !           124:       memcpy (ior->io_data, kmsg_buffer + kmsg_read_offset, amt);
        !           125:     }
        !           126:   else
        !           127:     {
        !           128:       int cnt;
        !           129: 
        !           130:       cnt = KMSGBUFSIZE - kmsg_read_offset;
        !           131:       memcpy (ior->io_data, kmsg_buffer + kmsg_read_offset, cnt);
        !           132:       memcpy (ior->io_data + cnt, kmsg_buffer, amt - cnt);
        !           133:     }
        !           134: 
        !           135:   kmsg_read_offset += amt;
        !           136:   if (kmsg_read_offset >= KMSGBUFSIZE)
        !           137:     kmsg_read_offset -= KMSGBUFSIZE;
        !           138:   
        !           139:   ior->io_residual = ior->io_count - amt;
        !           140:   
        !           141:   simple_unlock (&kmsg_lock);
        !           142:   return D_SUCCESS;
        !           143: }
        !           144: 
        !           145: static boolean_t
        !           146: kmsg_read_done (io_req_t ior)
        !           147: {
        !           148:   int err;
        !           149:   int amt, len;
        !           150: 
        !           151:   simple_lock (&kmsg_lock);
        !           152:   if (kmsg_read_offset == kmsg_write_offset)
        !           153:     {
        !           154:       /* The queue is empty.  */
        !           155:       ior->io_done = kmsg_read_done;
        !           156:       enqueue_tail (&kmsg_read_queue, ior);
        !           157:       simple_unlock (&kmsg_lock);
        !           158:       return FALSE;
        !           159:     }
        !           160: 
        !           161:   len = kmsg_write_offset - kmsg_read_offset;
        !           162:   if (len < 0)
        !           163:     len += KMSGBUFSIZE;
        !           164: 
        !           165:   amt = ior->io_count;
        !           166:   if (amt > len)
        !           167:     amt = len;
        !           168:   
        !           169:   if (kmsg_read_offset + amt <= KMSGBUFSIZE)
        !           170:     {
        !           171:       memcpy (ior->io_data, kmsg_buffer + kmsg_read_offset, amt);
        !           172:     }
        !           173:   else
        !           174:     {
        !           175:       int cnt;
        !           176: 
        !           177:       cnt = KMSGBUFSIZE - kmsg_read_offset;
        !           178:       memcpy (ior->io_data, kmsg_buffer + kmsg_read_offset, cnt);
        !           179:       memcpy (ior->io_data + cnt, kmsg_buffer, amt - cnt);
        !           180:     }
        !           181: 
        !           182:   kmsg_read_offset += amt;
        !           183:   if (kmsg_read_offset >= KMSGBUFSIZE)
        !           184:     kmsg_read_offset -= KMSGBUFSIZE;
        !           185:   
        !           186:   ior->io_residual = ior->io_count - amt;
        !           187: 
        !           188:   simple_unlock (&kmsg_lock);
        !           189:   ds_read_done (ior);
        !           190:   
        !           191:   return TRUE;
        !           192: }
        !           193: 
        !           194: io_return_t
        !           195: kmsggetstat (dev_t dev, int flavor, int *data, unsigned int *count)
        !           196: {
        !           197:   switch (flavor)
        !           198:     {
        !           199:     case DEV_GET_SIZE:
        !           200:       data[DEV_GET_SIZE_DEVICE_SIZE] = 0;
        !           201:       data[DEV_GET_SIZE_RECORD_SIZE] = 1;
        !           202:       *count = DEV_GET_SIZE_COUNT;
        !           203:       break;
        !           204: 
        !           205:     default:
        !           206:       return D_INVALID_OPERATION;
        !           207:     }
        !           208: 
        !           209:   return D_SUCCESS;
        !           210: }
        !           211: 
        !           212: /* Write to Kernel Message Buffer */
        !           213: void
        !           214: kmsg_putchar (int c)
        !           215: {
        !           216:   io_req_t ior;
        !           217:   int offset;
        !           218: 
        !           219:   /* XXX: cninit is not called before cnputc is used. So call kmsginit
        !           220:      here if not initialized yet.  */
        !           221:   if (!kmsg_init_done)
        !           222:     {
        !           223:       kmsginit ();
        !           224:       kmsg_init_done = 1;
        !           225:     }
        !           226:   
        !           227:   simple_lock (&kmsg_lock);
        !           228:   offset = kmsg_write_offset + 1;
        !           229:   if (offset == KMSGBUFSIZE)
        !           230:     offset = 0;
        !           231: 
        !           232:   if (offset == kmsg_read_offset)
        !           233:     {
        !           234:       /* Discard C.  */
        !           235:       simple_unlock (&kmsg_lock);
        !           236:       return;
        !           237:     }
        !           238: 
        !           239:   kmsg_buffer[kmsg_write_offset++] = c;
        !           240:   if (kmsg_write_offset == KMSGBUFSIZE)
        !           241:     kmsg_write_offset = 0;
        !           242: 
        !           243:   while ((ior = (io_req_t) dequeue_head (&kmsg_read_queue)) != NULL)
        !           244:     iodone (ior);
        !           245: 
        !           246:   simple_unlock (&kmsg_lock);
        !           247: }

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