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#include "monitor.h"
#ifndef MINI_BUF
int disk_drive = 0;
int disk_spt = 7;
int disk_heads = 2;
int disk_cyls = 0;
static int last_drive = 0;
static int data_len = 0;
static long data_trk1 = 0;
static char * data_buf1 = 0;
static long data_trk2 = 0;
static char * data_buf2 = 0;
static long bad_track = -1; /* Track number of last unsuccesful read */
static long get_dpt();
void reset_disk()
{
if( data_buf1 ) free(data_buf1);
if( data_buf2 ) free(data_buf2);
data_buf1 = data_buf2 = 0;
last_drive = disk_drive;
bad_track = -1;
if( !(disk_drive & 0x80 ) )
{
disk_spt = 7; /* Defaults for reading Boot area. */
disk_heads = 2;
disk_cyls = 0;
}
#if defined(__MSDOS__) || defined(__STANDALONE__)
else
{
/* Hard disk, get parameters from bios */
long dpt;
int v;
disk_spt = 17; /* Defaults for reading Boot area. */
disk_heads = 1;
disk_cyls = 0;
dpt = get_dpt(disk_drive);
v = ((dpt>>16) & 0xFF);
if( v == 0xFF || v <= (disk_drive&0x7F) ) return; /* Bad dpt */
disk_spt = (dpt & 0x3F); /* Max sector number 1-63 */
if( disk_spt == 0 ) disk_spt = 64; /* 1-64 ? */
disk_heads = ((dpt>>24) & 0xFF) + 1; /* Head count 1-256 */
disk_cyls = ((dpt>>8) & 0xFF) + ((dpt<<2) & 0x300) + 1;
/* Cyls count, unchecked, only needs != 0, if AMI 386 bios can be
* upto 4096 cylinder, otherwise BIOS limit is 1024 cyl.
*/
}
#endif
}
char * read_lsector(sectno)
long sectno;
{
int tries = 6;
int rv;
int phy_s = 1;
int phy_h = 0;
int phy_c = 0;
if( disk_drive != last_drive || sectno == 0 ) reset_disk();
if( disk_spt < 0 || disk_spt > 63 || disk_heads < 1 )
{
phy_s = sectno;
reset_disk();
#ifdef __ELKS__
fprintf(stderr, "read_sector(%ld = %d,%d,%d)\n",
sectno, phy_c, phy_h, phy_s+1);
#endif
}
else
{
phy_s = sectno%disk_spt;
phy_h = sectno/disk_spt%disk_heads;
phy_c = sectno/disk_spt/disk_heads;
#ifdef __ELKS__
fprintf(stderr, "read_sector(%ld = %d,%d,%d)\n",
sectno, phy_c, phy_h, phy_s+1);
#endif
if( fetch_track_buf(phy_c, phy_h, phy_s) >= 0 )
return data_buf1 + (phy_s % data_len) * 512;
}
data_len = -1; /* Zap the cache */
if( data_buf1 == 0 )
data_buf1 = malloc(512);
if( data_buf1 == 0 )
{
printf("Cannot allocate memory for disk read!!!\n");
return 0;
}
#ifdef __ELKS__
fprintf(stderr, "WARNING: Single sector read\n");
#endif
do
{
rv = phy_read(disk_drive, phy_c, phy_h, phy_s+1, 1, data_buf1);
tries--;
}
while(rv && tries > 0);
if( rv ) printf("Disk error 0x%02x %d:%d:%d:%d[%2d] -> 0x%04x[]\n",
rv, disk_drive, phy_c, phy_h, phy_s+1, 1, data_buf1);
if(rv) return 0; else return data_buf1;
}
fetch_track_buf(phy_c, phy_h, phy_s)
int phy_c, phy_h, phy_s;
{
long trk_no, t;
char * p;
int tries = 3;
int rv, nlen;
/* Big tracks get us short of memory so limit it. */
nlen = (disk_spt-1)/24;
nlen = (disk_spt+nlen)/(nlen+1);
trk_no = (long)phy_c*disk_heads*4+phy_h*4+phy_s/nlen+1;
if( data_len != nlen )
{
if( data_buf1 ) free(data_buf1);
if( data_buf2 ) free(data_buf2);
data_buf1 = data_buf2 = 0;
data_len = disk_spt;
}
if( trk_no == bad_track ) return -1;
if( data_buf1 && trk_no == data_trk1 ) return 0;
/* Two cases:
* 1) buffer2 has the one we want, need to swap to make it most recent
* 2) Neither has it, need to swap to overwrite least recent.
*/
/* So we always swap */
p = data_buf1; data_buf1 = data_buf2; data_buf2 = p;
t = data_trk1; data_trk1 = data_trk2; data_trk2 = t;
/* The other one right ? */
if( data_buf1 && trk_no == data_trk1 ) return 0;
/* If we get here we have to do a physical read ... */
/* into data_buf1. */
if( data_buf1 == 0 )
{
data_buf1 = malloc(disk_spt*512);
#ifdef __ELKS__
fprintf(stderr, "Allocated buffer to %d\n", data_buf1);
#endif
}
if( data_buf1 == 0 )
{
/* Is buf2 allocated ? Yes take it! */
data_buf1 = data_buf2; data_buf2 = 0; data_trk2 = -1;
}
data_trk1 = -1;
/* Not enough memory for track read. */
if( data_buf1 == 0 ) return -1;
do /* the physical read */
{
rv = phy_read(disk_drive, phy_c, phy_h, phy_s/data_len+1, data_len,
data_buf1);
tries--;
}
while(rv && tries > 0);
if( rv ) printf("Disk error 0x%02x %d:%d:%d:%d[%2d] -> 0x%04x[]\n",
rv, disk_drive, phy_c, phy_h, phy_s/data_len+1, data_len, data_buf1);
/* Disk error, it'll try one at a time, _very_ slowly! */
if(rv)
{
bad_track = trk_no;
return -1;
}
/* Yes! */
data_trk1 = trk_no;
return 0;
}
#if defined(__MSDOS__) || defined(__STANDALONE__)
phy_read(drive, cyl, head, sect, length, buffer)
{
#asm
push bp
mov bp,sp
push es
push ds
pop es
mov dl,[bp+2+_phy_read.drive]
mov ch,[bp+2+_phy_read.cyl]
mov dh,[bp+2+_phy_read.head]
mov bx,[bp+2+_phy_read.buffer]
mov ax,[bp+2+_phy_read.cyl] ! Bits 10-11 of cylinder, AMI BIOS.
mov cl,#4
sar ax,cl
and al,#$C0
xor dh,al
mov cl,[bp+2+_phy_read.sect]
and cl,#$3F
mov ax,[bp+2+_phy_read.cyl] ! Bits 8-9 of cylinder.
sar ax,#1
sar ax,#1
and al,#$C0
or cl,al
mov al,[bp+2+_phy_read.length]
mov ah,#$02
int $13
jc read_err
mov ax,#0
read_err:
pop es
pop bp
#endasm
}
long
get_dpt(drive)
{
#asm
push bp
mov bp,sp
push di
push es
mov dl,[bp+2+_get_dpt.drive]
mov ah,#$08
int $13
jnc func_ok
mov cx,ax
mov dx,#-1
func_ok:
mov ax,cx
pop es
pop di
pop bp
#endasm
}
#endif
#endif
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