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biosdisk_ll.c revision 1.2 
      1 /*	$NetBSD: biosdisk_ll.c,v 1.2 1997/03/22 01:41:36 thorpej Exp $	 */
      2 
      3 /*
      4  * Copyright (c) 1996
      5  * 	Matthias Drochner.  All rights reserved.
      6  * Copyright (c) 1996
      7  * 	Perry E. Metzger.  All rights reserved.
      8  *
      9  * Redistribution and use in source and binary forms, with or without
     10  * modification, are permitted provided that the following conditions
     11  * are met:
     12  * 1. Redistributions of source code must retain the above copyright
     13  *    notice, this list of conditions and the following disclaimer.
     14  * 2. Redistributions in binary form must reproduce the above copyright
     15  *    notice, this list of conditions and the following disclaimer in the
     16  *    documentation and/or other materials provided with the distribution.
     17  * 3. All advertising materials mentioning features or use of this software
     18  *    must display the following acknowledgements:
     19  *	This product includes software developed for the NetBSD Project
     20  *	by Matthias Drochner.
     21  *	This product includes software developed for the NetBSD Project
     22  *	by Perry E. Metzger.
     23  * 4. The names of the authors may not be used to endorse or promote products
     24  *    derived from this software without specific prior written permission.
     25  *
     26  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
     27  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
     28  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
     29  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
     30  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
     31  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
     32  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
     33  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
     34  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
     35  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     36  */
     37 
     38 /*
     39  * shared by bootsector startup (bootsectmain) and biosdisk.c needs lowlevel
     40  * parts from bios_disk.S
     41  */
     42 
     43 #include <lib/libsa/stand.h>
     44 
     45 #include "biosdisk_ll.h"
     46 #include "diskbuf.h"
     47 
     48 extern int get_diskinfo __P((int));
     49 extern int biosread __P((int, int, int, int, int, char *));
     50 
     51 #define	SPT(di)		((di)&0xff)
     52 #define	HEADS(di)	((((di)>>8)&0xff)+1)
     53 
     54 int
     55 set_geometry(d)
     56 	struct biosdisk_ll *d;
     57 {
     58 	int             diskinfo;
     59 
     60 	diskinfo = get_diskinfo(d->dev);
     61 
     62 	d->spc = (d->spt = SPT(diskinfo)) * HEADS(diskinfo);
     63 
     64 	/*
     65 	 * get_diskinfo assumes floppy if BIOS call fails. Check at least
     66 	 * "valid" geometry.
     67 	 */
     68 	return (!d->spc || !d->spt);
     69 }
     70 
     71 /*
     72  * Global shared "diskbuf" is used as read ahead buffer.  For reading from
     73  * floppies, the bootstrap has to be loaded on a 64K boundary to ensure that
     74  * this buffer doesn't cross a 64K DMA boundary.
     75  */
     76 #define RA_SECTORS      (DISKBUFSIZE / BIOSDISK_SECSIZE)
     77 static int      ra_dev;
     78 static int      ra_end;
     79 static int      ra_first;
     80 
     81 int
     82 readsects(d, dblk, num, buf, cold)	/* reads ahead if (!cold) */
     83 	struct biosdisk_ll *d;
     84 	int             dblk, num;
     85 	char           *buf;
     86 	int             cold;	/* don't use data segment or bss, don't call
     87 				 * library functions */
     88 {
     89 	while (num) {
     90 		int             nsec;
     91 
     92 		/* check for usable data in read-ahead buffer */
     93 		if (cold || diskbuf_user != &ra_dev || d->dev != ra_dev
     94 		    || dblk < ra_first || dblk >= ra_end) {
     95 
     96 			/* no, read from disk */
     97 			int             cyl, head, sec;
     98 			char           *trbuf;
     99 
    100 			cyl = dblk / d->spc;
    101 			head = (dblk % d->spc) / d->spt;
    102 			sec = dblk % d->spt;
    103 			nsec = d->spt - sec;
    104 
    105 			if (cold) {
    106 				/* transfer directly to buffer */
    107 				trbuf = buf;
    108 				if (nsec > num)
    109 					nsec = num;
    110 			} else {
    111 				/* fill read-ahead buffer */
    112 				trbuf = diskbuf;
    113 				if (nsec > RA_SECTORS)
    114 					nsec = RA_SECTORS;
    115 
    116 				ra_dev = d->dev;
    117 				ra_first = dblk;
    118 				ra_end = dblk + nsec;
    119 				diskbuf_user = &ra_dev;
    120 			}
    121 
    122 			if (biosread(d->dev, cyl, head, sec, nsec, trbuf)) {
    123 				if (!cold)
    124 					diskbuf_user = 0; /* mark invalid */
    125 				return (-1);	/* XXX cannot output here if
    126 						 * (cold) */
    127 			}
    128 		} else		/* can take blocks from end of read-ahead
    129 				 * buffer */
    130 			nsec = ra_end - dblk;
    131 
    132 		if (!cold) {
    133 			/* copy data from read-ahead to user buffer */
    134 			if (nsec > num)
    135 				nsec = num;
    136 			bcopy(diskbuf + (dblk - ra_first) * BIOSDISK_SECSIZE,
    137 			    buf, nsec * BIOSDISK_SECSIZE);
    138 		}
    139 		buf += nsec * BIOSDISK_SECSIZE;
    140 		num -= nsec;
    141 		dblk += nsec;
    142 	}
    143 
    144 	return (0);
    145 }
    146