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amiflop.c
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amiflop.c
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/*
* linux/amiga/amiflop.c
*
* Copyright (C) 1993 Greg Harp
* Portions of this driver are based on code contributed by Brad Pepers
*
* revised 28.5.95 by Joerg Dorchain
* - now no bugs(?) any more for both HD & DD
* - added support for 40 Track 5.25" drives, 80-track hopefully behaves
* like 3.5" dd (no way to test - are there any 5.25" drives out there
* that work on an A4000?)
* - wrote formatting routine (maybe dirty, but works)
*
* june/july 1995 added ms-dos support by Joerg Dorchain
* (portions based on messydos.device and various contributors)
* - currently only 9 and 18 sector disks
*
* - fixed a bug with the internal trackbuffer when using multiple
* disks the same time
* - made formatting a bit safer
* - added command line and machine based default for "silent" df0
*
* december 1995 adapted for 1.2.13pl4 by Joerg Dorchain
* - works but I think it's inefficient. (look in redo_fd_request)
* But the changes were very efficient. (only three and a half lines)
*
* january 1996 added special ioctl for tracking down read/write problems
* - usage ioctl(d, RAW_TRACK, ptr); the raw track buffer (MFM-encoded data
* is copied to area. (area should be large enough since no checking is
* done - 30K is currently sufficient). return the actual size of the
* trackbuffer
* - replaced udelays() by a timer (CIAA timer B) for the waits
* needed for the disk mechanic.
*
* february 1996 fixed error recovery and multiple disk access
* - both got broken the first time I tampered with the driver :-(
* - still not safe, but better than before
*
* revised Marts 3rd, 1996 by Jes Sorensen for use in the 1.3.28 kernel.
* - Minor changes to accept the kdev_t.
* - Replaced some more udelays with ms_delays. Udelay is just a loop,
* and so the delay will be different depending on the given
* processor :-(
* - The driver could use a major cleanup because of the new
* major/minor handling that came with kdev_t. It seems to work for
* the time being, but I can't guarantee that it will stay like
* that when we start using 16 (24?) bit minors.
*
* restructured jan 1997 by Joerg Dorchain
* - Fixed Bug accessing multiple disks
* - some code cleanup
* - added trackbuffer for each drive to speed things up
* - fixed some race conditions (who finds the next may send it to me ;-)
*/
#include <linux/module.h>
#include <linux/fd.h>
#include <linux/hdreg.h>
#include <linux/delay.h>
#include <linux/init.h>
#include <linux/amifdreg.h>
#include <linux/amifd.h>
#include <linux/buffer_head.h>
#include <linux/blkdev.h>
#include <linux/elevator.h>
#include <linux/interrupt.h>
#include <asm/setup.h>
#include <asm/uaccess.h>
#include <asm/amigahw.h>
#include <asm/amigaints.h>
#include <asm/irq.h>
#undef DEBUG /* print _LOTS_ of infos */
#define RAW_IOCTL
#ifdef RAW_IOCTL
#define IOCTL_RAW_TRACK 0x5254524B /* 'RTRK' */
#endif
/*
* Defines
*/
/*
* Error codes
*/
#define FD_OK 0 /* operation succeeded */
#define FD_ERROR -1 /* general error (seek, read, write, etc) */
#define FD_NOUNIT 1 /* unit does not exist */
#define FD_UNITBUSY 2 /* unit already active */
#define FD_NOTACTIVE 3 /* unit is not active */
#define FD_NOTREADY 4 /* unit is not ready (motor not on/no disk) */
#define MFM_NOSYNC 1
#define MFM_HEADER 2
#define MFM_DATA 3
#define MFM_TRACK 4
/*
* Floppy ID values
*/
#define FD_NODRIVE 0x00000000 /* response when no unit is present */
#define FD_DD_3 0xffffffff /* double-density 3.5" (880K) drive */
#define FD_HD_3 0x55555555 /* high-density 3.5" (1760K) drive */
#define FD_DD_5 0xaaaaaaaa /* double-density 5.25" (440K) drive */
static unsigned long int fd_def_df0 = FD_DD_3; /* default for df0 if it doesn't identify */
module_param(fd_def_df0, ulong, 0);
MODULE_LICENSE("GPL");
static struct request_queue *floppy_queue;
/*
* Macros
*/
#define MOTOR_ON (ciab.prb &= ~DSKMOTOR)
#define MOTOR_OFF (ciab.prb |= DSKMOTOR)
#define SELECT(mask) (ciab.prb &= ~mask)
#define DESELECT(mask) (ciab.prb |= mask)
#define SELMASK(drive) (1 << (3 + (drive & 3)))
static struct fd_drive_type drive_types[] = {
/* code name tr he rdsz wrsz sm pc1 pc2 sd st st*/
/* warning: times are now in milliseconds (ms) */
{ FD_DD_3, "DD 3.5", 80, 2, 14716, 13630, 1, 80,161, 3, 18, 1},
{ FD_HD_3, "HD 3.5", 80, 2, 28344, 27258, 2, 80,161, 3, 18, 1},
{ FD_DD_5, "DD 5.25", 40, 2, 14716, 13630, 1, 40, 81, 6, 30, 2},
{ FD_NODRIVE, "No Drive", 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}
};
static int num_dr_types = ARRAY_SIZE(drive_types);
static int amiga_read(int), dos_read(int);
static void amiga_write(int), dos_write(int);
static struct fd_data_type data_types[] = {
{ "Amiga", 11 , amiga_read, amiga_write},
{ "MS-Dos", 9, dos_read, dos_write}
};
/* current info on each unit */
static struct amiga_floppy_struct unit[FD_MAX_UNITS];
static struct timer_list flush_track_timer[FD_MAX_UNITS];
static struct timer_list post_write_timer;
static struct timer_list motor_on_timer;
static struct timer_list motor_off_timer[FD_MAX_UNITS];
static int on_attempts;
/* Synchronization of FDC access */
/* request loop (trackbuffer) */
static volatile int fdc_busy = -1;
static volatile int fdc_nested;
static DECLARE_WAIT_QUEUE_HEAD(fdc_wait);
static DECLARE_COMPLETION(motor_on_completion);
static volatile int selected = -1; /* currently selected drive */
static int writepending;
static int writefromint;
static char *raw_buf;
static DEFINE_SPINLOCK(amiflop_lock);
#define RAW_BUF_SIZE 30000 /* size of raw disk data */
/*
* These are global variables, as that's the easiest way to give
* information to interrupts. They are the data used for the current
* request.
*/
static volatile char block_flag;
static DECLARE_WAIT_QUEUE_HEAD(wait_fd_block);
/* MS-Dos MFM Coding tables (should go quick and easy) */
static unsigned char mfmencode[16]={
0x2a, 0x29, 0x24, 0x25, 0x12, 0x11, 0x14, 0x15,
0x4a, 0x49, 0x44, 0x45, 0x52, 0x51, 0x54, 0x55
};
static unsigned char mfmdecode[128];
/* floppy internal millisecond timer stuff */
static DECLARE_COMPLETION(ms_wait_completion);
#define MS_TICKS ((amiga_eclock+50)/1000)
/*
* Note that MAX_ERRORS=X doesn't imply that we retry every bad read
* max X times - some types of errors increase the errorcount by 2 or
* even 3, so we might actually retry only X/2 times before giving up.
*/
#define MAX_ERRORS 12
#define custom amiga_custom
/* Prevent "aliased" accesses. */
static int fd_ref[4] = { 0,0,0,0 };
static int fd_device[4] = { 0, 0, 0, 0 };
/*
* Here come the actual hardware access and helper functions.
* They are not reentrant and single threaded because all drives
* share the same hardware and the same trackbuffer.
*/
/* Milliseconds timer */
static irqreturn_t ms_isr(int irq, void *dummy)
{
complete(&ms_wait_completion);
return IRQ_HANDLED;
}
/* all waits are queued up
A more generic routine would do a schedule a la timer.device */
static void ms_delay(int ms)
{
int ticks;
static DEFINE_MUTEX(mutex);
if (ms > 0) {
mutex_lock(&mutex);
ticks = MS_TICKS*ms-1;
ciaa.tblo=ticks%256;
ciaa.tbhi=ticks/256;
ciaa.crb=0x19; /*count eclock, force load, one-shoot, start */
wait_for_completion(&ms_wait_completion);
mutex_unlock(&mutex);
}
}
/* Hardware semaphore */
/* returns true when we would get the semaphore */
static inline int try_fdc(int drive)
{
drive &= 3;
return ((fdc_busy < 0) || (fdc_busy == drive));
}
static void get_fdc(int drive)
{
unsigned long flags;
drive &= 3;
#ifdef DEBUG
printk("get_fdc: drive %d fdc_busy %d fdc_nested %d\n",drive,fdc_busy,fdc_nested);
#endif
local_irq_save(flags);
wait_event(fdc_wait, try_fdc(drive));
fdc_busy = drive;
fdc_nested++;
local_irq_restore(flags);
}
static inline void rel_fdc(void)
{
#ifdef DEBUG
if (fdc_nested == 0)
printk("fd: unmatched rel_fdc\n");
printk("rel_fdc: fdc_busy %d fdc_nested %d\n",fdc_busy,fdc_nested);
#endif
fdc_nested--;
if (fdc_nested == 0) {
fdc_busy = -1;
wake_up(&fdc_wait);
}
}
static void fd_select (int drive)
{
unsigned char prb = ~0;
drive&=3;
#ifdef DEBUG
printk("selecting %d\n",drive);
#endif
if (drive == selected)
return;
get_fdc(drive);
selected = drive;
if (unit[drive].track % 2 != 0)
prb &= ~DSKSIDE;
if (unit[drive].motor == 1)
prb &= ~DSKMOTOR;
ciab.prb |= (SELMASK(0)|SELMASK(1)|SELMASK(2)|SELMASK(3));
ciab.prb = prb;
prb &= ~SELMASK(drive);
ciab.prb = prb;
rel_fdc();
}
static void fd_deselect (int drive)
{
unsigned char prb;
unsigned long flags;
drive&=3;
#ifdef DEBUG
printk("deselecting %d\n",drive);
#endif
if (drive != selected) {
printk(KERN_WARNING "Deselecting drive %d while %d was selected!\n",drive,selected);
return;
}
get_fdc(drive);
local_irq_save(flags);
selected = -1;
prb = ciab.prb;
prb |= (SELMASK(0)|SELMASK(1)|SELMASK(2)|SELMASK(3));
ciab.prb = prb;
local_irq_restore (flags);
rel_fdc();
}
static void motor_on_callback(unsigned long nr)
{
if (!(ciaa.pra & DSKRDY) || --on_attempts == 0) {
complete_all(&motor_on_completion);
} else {
motor_on_timer.expires = jiffies + HZ/10;
add_timer(&motor_on_timer);
}
}
static int fd_motor_on(int nr)
{
nr &= 3;
del_timer(motor_off_timer + nr);
if (!unit[nr].motor) {
unit[nr].motor = 1;
fd_select(nr);
INIT_COMPLETION(motor_on_completion);
motor_on_timer.data = nr;
mod_timer(&motor_on_timer, jiffies + HZ/2);
on_attempts = 10;
wait_for_completion(&motor_on_completion);
fd_deselect(nr);
}
if (on_attempts == 0) {
on_attempts = -1;
#if 0
printk (KERN_ERR "motor_on failed, turning motor off\n");
fd_motor_off (nr);
return 0;
#else
printk (KERN_WARNING "DSKRDY not set after 1.5 seconds - assuming drive is spinning notwithstanding\n");
#endif
}
return 1;
}
static void fd_motor_off(unsigned long drive)
{
long calledfromint;
#ifdef MODULE
long decusecount;
decusecount = drive & 0x40000000;
#endif
calledfromint = drive & 0x80000000;
drive&=3;
if (calledfromint && !try_fdc(drive)) {
/* We would be blocked in an interrupt, so try again later */
motor_off_timer[drive].expires = jiffies + 1;
add_timer(motor_off_timer + drive);
return;
}
unit[drive].motor = 0;
fd_select(drive);
udelay (1);
fd_deselect(drive);
}
static void floppy_off (unsigned int nr)
{
int drive;
drive = nr & 3;
/* called this way it is always from interrupt */
motor_off_timer[drive].data = nr | 0x80000000;
mod_timer(motor_off_timer + drive, jiffies + 3*HZ);
}
static int fd_calibrate(int drive)
{
unsigned char prb;
int n;
drive &= 3;
get_fdc(drive);
if (!fd_motor_on (drive))
return 0;
fd_select (drive);
prb = ciab.prb;
prb |= DSKSIDE;
prb &= ~DSKDIREC;
ciab.prb = prb;
for (n = unit[drive].type->tracks/2; n != 0; --n) {
if (ciaa.pra & DSKTRACK0)
break;
prb &= ~DSKSTEP;
ciab.prb = prb;
prb |= DSKSTEP;
udelay (2);
ciab.prb = prb;
ms_delay(unit[drive].type->step_delay);
}
ms_delay (unit[drive].type->settle_time);
prb |= DSKDIREC;
n = unit[drive].type->tracks + 20;
for (;;) {
prb &= ~DSKSTEP;
ciab.prb = prb;
prb |= DSKSTEP;
udelay (2);
ciab.prb = prb;
ms_delay(unit[drive].type->step_delay + 1);
if ((ciaa.pra & DSKTRACK0) == 0)
break;
if (--n == 0) {
printk (KERN_ERR "fd%d: calibrate failed, turning motor off\n", drive);
fd_motor_off (drive);
unit[drive].track = -1;
rel_fdc();
return 0;
}
}
unit[drive].track = 0;
ms_delay(unit[drive].type->settle_time);
rel_fdc();
fd_deselect(drive);
return 1;
}
static int fd_seek(int drive, int track)
{
unsigned char prb;
int cnt;
#ifdef DEBUG
printk("seeking drive %d to track %d\n",drive,track);
#endif
drive &= 3;
get_fdc(drive);
if (unit[drive].track == track) {
rel_fdc();
return 1;
}
if (!fd_motor_on(drive)) {
rel_fdc();
return 0;
}
if (unit[drive].track < 0 && !fd_calibrate(drive)) {
rel_fdc();
return 0;
}
fd_select (drive);
cnt = unit[drive].track/2 - track/2;
prb = ciab.prb;
prb |= DSKSIDE | DSKDIREC;
if (track % 2 != 0)
prb &= ~DSKSIDE;
if (cnt < 0) {
cnt = - cnt;
prb &= ~DSKDIREC;
}
ciab.prb = prb;
if (track % 2 != unit[drive].track % 2)
ms_delay (unit[drive].type->side_time);
unit[drive].track = track;
if (cnt == 0) {
rel_fdc();
fd_deselect(drive);
return 1;
}
do {
prb &= ~DSKSTEP;
ciab.prb = prb;
prb |= DSKSTEP;
udelay (1);
ciab.prb = prb;
ms_delay (unit[drive].type->step_delay);
} while (--cnt != 0);
ms_delay (unit[drive].type->settle_time);
rel_fdc();
fd_deselect(drive);
return 1;
}
static unsigned long fd_get_drive_id(int drive)
{
int i;
ulong id = 0;
drive&=3;
get_fdc(drive);
/* set up for ID */
MOTOR_ON;
udelay(2);
SELECT(SELMASK(drive));
udelay(2);
DESELECT(SELMASK(drive));
udelay(2);
MOTOR_OFF;
udelay(2);
SELECT(SELMASK(drive));
udelay(2);
DESELECT(SELMASK(drive));
udelay(2);
/* loop and read disk ID */
for (i=0; i<32; i++) {
SELECT(SELMASK(drive));
udelay(2);
/* read and store value of DSKRDY */
id <<= 1;
id |= (ciaa.pra & DSKRDY) ? 0 : 1; /* cia regs are low-active! */
DESELECT(SELMASK(drive));
}
rel_fdc();
/*
* RB: At least A500/A2000's df0: don't identify themselves.
* As every (real) Amiga has at least a 3.5" DD drive as df0:
* we default to that if df0: doesn't identify as a certain
* type.
*/
if(drive == 0 && id == FD_NODRIVE)
{
id = fd_def_df0;
printk(KERN_NOTICE "fd: drive 0 didn't identify, setting default %08lx\n", (ulong)fd_def_df0);
}
/* return the ID value */
return (id);
}
static irqreturn_t fd_block_done(int irq, void *dummy)
{
if (block_flag)
custom.dsklen = 0x4000;
if (block_flag == 2) { /* writing */
writepending = 2;
post_write_timer.expires = jiffies + 1; /* at least 2 ms */
post_write_timer.data = selected;
add_timer(&post_write_timer);
}
else { /* reading */
block_flag = 0;
wake_up (&wait_fd_block);
}
return IRQ_HANDLED;
}
static void raw_read(int drive)
{
drive&=3;
get_fdc(drive);
wait_event(wait_fd_block, !block_flag);
fd_select(drive);
/* setup adkcon bits correctly */
custom.adkcon = ADK_MSBSYNC;
custom.adkcon = ADK_SETCLR|ADK_WORDSYNC|ADK_FAST;
custom.dsksync = MFM_SYNC;
custom.dsklen = 0;
custom.dskptr = (u_char *)ZTWO_PADDR((u_char *)raw_buf);
custom.dsklen = unit[drive].type->read_size/sizeof(short) | DSKLEN_DMAEN;
custom.dsklen = unit[drive].type->read_size/sizeof(short) | DSKLEN_DMAEN;
block_flag = 1;
wait_event(wait_fd_block, !block_flag);
custom.dsklen = 0;
fd_deselect(drive);
rel_fdc();
}
static int raw_write(int drive)
{
ushort adk;
drive&=3;
get_fdc(drive); /* corresponds to rel_fdc() in post_write() */
if ((ciaa.pra & DSKPROT) == 0) {
rel_fdc();
return 0;
}
wait_event(wait_fd_block, !block_flag);
fd_select(drive);
/* clear adkcon bits */
custom.adkcon = ADK_PRECOMP1|ADK_PRECOMP0|ADK_WORDSYNC|ADK_MSBSYNC;
/* set appropriate adkcon bits */
adk = ADK_SETCLR|ADK_FAST;
if ((ulong)unit[drive].track >= unit[drive].type->precomp2)
adk |= ADK_PRECOMP1;
else if ((ulong)unit[drive].track >= unit[drive].type->precomp1)
adk |= ADK_PRECOMP0;
custom.adkcon = adk;
custom.dsklen = DSKLEN_WRITE;
custom.dskptr = (u_char *)ZTWO_PADDR((u_char *)raw_buf);
custom.dsklen = unit[drive].type->write_size/sizeof(short) | DSKLEN_DMAEN|DSKLEN_WRITE;
custom.dsklen = unit[drive].type->write_size/sizeof(short) | DSKLEN_DMAEN|DSKLEN_WRITE;
block_flag = 2;
return 1;
}
/*
* to be called at least 2ms after the write has finished but before any
* other access to the hardware.
*/
static void post_write (unsigned long drive)
{
#ifdef DEBUG
printk("post_write for drive %ld\n",drive);
#endif
drive &= 3;
custom.dsklen = 0;
block_flag = 0;
writepending = 0;
writefromint = 0;
unit[drive].dirty = 0;
wake_up(&wait_fd_block);
fd_deselect(drive);
rel_fdc(); /* corresponds to get_fdc() in raw_write */
}
/*
* The following functions are to convert the block contents into raw data
* written to disk and vice versa.
* (Add other formats here ;-))
*/
static unsigned long scan_sync(unsigned long raw, unsigned long end)
{
ushort *ptr = (ushort *)raw, *endp = (ushort *)end;
while (ptr < endp && *ptr++ != 0x4489)
;
if (ptr < endp) {
while (*ptr == 0x4489 && ptr < endp)
ptr++;
return (ulong)ptr;
}
return 0;
}
static inline unsigned long checksum(unsigned long *addr, int len)
{
unsigned long csum = 0;
len /= sizeof(*addr);
while (len-- > 0)
csum ^= *addr++;
csum = ((csum>>1) & 0x55555555) ^ (csum & 0x55555555);
return csum;
}
static unsigned long decode (unsigned long *data, unsigned long *raw,
int len)
{
ulong *odd, *even;
/* convert length from bytes to longwords */
len >>= 2;
odd = raw;
even = odd + len;
/* prepare return pointer */
raw += len * 2;
do {
*data++ = ((*odd++ & 0x55555555) << 1) | (*even++ & 0x55555555);
} while (--len != 0);
return (ulong)raw;
}
struct header {
unsigned char magic;
unsigned char track;
unsigned char sect;
unsigned char ord;
unsigned char labels[16];
unsigned long hdrchk;
unsigned long datachk;
};
static int amiga_read(int drive)
{
unsigned long raw;
unsigned long end;
int scnt;
unsigned long csum;
struct header hdr;
drive&=3;
raw = (long) raw_buf;
end = raw + unit[drive].type->read_size;
for (scnt = 0;scnt < unit[drive].dtype->sects * unit[drive].type->sect_mult; scnt++) {
if (!(raw = scan_sync(raw, end))) {
printk (KERN_INFO "can't find sync for sector %d\n", scnt);
return MFM_NOSYNC;
}
raw = decode ((ulong *)&hdr.magic, (ulong *)raw, 4);
raw = decode ((ulong *)&hdr.labels, (ulong *)raw, 16);
raw = decode ((ulong *)&hdr.hdrchk, (ulong *)raw, 4);
raw = decode ((ulong *)&hdr.datachk, (ulong *)raw, 4);
csum = checksum((ulong *)&hdr,
(char *)&hdr.hdrchk-(char *)&hdr);
#ifdef DEBUG
printk ("(%x,%d,%d,%d) (%lx,%lx,%lx,%lx) %lx %lx\n",
hdr.magic, hdr.track, hdr.sect, hdr.ord,
*(ulong *)&hdr.labels[0], *(ulong *)&hdr.labels[4],
*(ulong *)&hdr.labels[8], *(ulong *)&hdr.labels[12],
hdr.hdrchk, hdr.datachk);
#endif
if (hdr.hdrchk != csum) {
printk(KERN_INFO "MFM_HEADER: %08lx,%08lx\n", hdr.hdrchk, csum);
return MFM_HEADER;
}
/* verify track */
if (hdr.track != unit[drive].track) {
printk(KERN_INFO "MFM_TRACK: %d, %d\n", hdr.track, unit[drive].track);
return MFM_TRACK;
}
raw = decode ((ulong *)(unit[drive].trackbuf + hdr.sect*512),
(ulong *)raw, 512);
csum = checksum((ulong *)(unit[drive].trackbuf + hdr.sect*512), 512);
if (hdr.datachk != csum) {
printk(KERN_INFO "MFM_DATA: (%x:%d:%d:%d) sc=%d %lx, %lx\n",
hdr.magic, hdr.track, hdr.sect, hdr.ord, scnt,
hdr.datachk, csum);
printk (KERN_INFO "data=(%lx,%lx,%lx,%lx)\n",
((ulong *)(unit[drive].trackbuf+hdr.sect*512))[0],
((ulong *)(unit[drive].trackbuf+hdr.sect*512))[1],
((ulong *)(unit[drive].trackbuf+hdr.sect*512))[2],
((ulong *)(unit[drive].trackbuf+hdr.sect*512))[3]);
return MFM_DATA;
}
}
return 0;
}
static void encode(unsigned long data, unsigned long *dest)
{
unsigned long data2;
data &= 0x55555555;
data2 = data ^ 0x55555555;
data |= ((data2 >> 1) | 0x80000000) & (data2 << 1);
if (*(dest - 1) & 0x00000001)
data &= 0x7FFFFFFF;
*dest = data;
}
static void encode_block(unsigned long *dest, unsigned long *src, int len)
{
int cnt, to_cnt = 0;
unsigned long data;
/* odd bits */
for (cnt = 0; cnt < len / 4; cnt++) {
data = src[cnt] >> 1;
encode(data, dest + to_cnt++);
}
/* even bits */
for (cnt = 0; cnt < len / 4; cnt++) {
data = src[cnt];
encode(data, dest + to_cnt++);
}
}
static unsigned long *putsec(int disk, unsigned long *raw, int cnt)
{
struct header hdr;
int i;
disk&=3;
*raw = (raw[-1]&1) ? 0x2AAAAAAA : 0xAAAAAAAA;
raw++;
*raw++ = 0x44894489;
hdr.magic = 0xFF;
hdr.track = unit[disk].track;
hdr.sect = cnt;
hdr.ord = unit[disk].dtype->sects * unit[disk].type->sect_mult - cnt;
for (i = 0; i < 16; i++)
hdr.labels[i] = 0;
hdr.hdrchk = checksum((ulong *)&hdr,
(char *)&hdr.hdrchk-(char *)&hdr);
hdr.datachk = checksum((ulong *)(unit[disk].trackbuf+cnt*512), 512);
encode_block(raw, (ulong *)&hdr.magic, 4);
raw += 2;
encode_block(raw, (ulong *)&hdr.labels, 16);
raw += 8;
encode_block(raw, (ulong *)&hdr.hdrchk, 4);
raw += 2;
encode_block(raw, (ulong *)&hdr.datachk, 4);
raw += 2;
encode_block(raw, (ulong *)(unit[disk].trackbuf+cnt*512), 512);
raw += 256;
return raw;
}
static void amiga_write(int disk)
{
unsigned int cnt;
unsigned long *ptr = (unsigned long *)raw_buf;
disk&=3;
/* gap space */
for (cnt = 0; cnt < 415 * unit[disk].type->sect_mult; cnt++)
*ptr++ = 0xaaaaaaaa;
/* sectors */
for (cnt = 0; cnt < unit[disk].dtype->sects * unit[disk].type->sect_mult; cnt++)
ptr = putsec (disk, ptr, cnt);
*(ushort *)ptr = (ptr[-1]&1) ? 0x2AA8 : 0xAAA8;
}
struct dos_header {
unsigned char track, /* 0-80 */
side, /* 0-1 */
sec, /* 0-...*/
len_desc;/* 2 */
unsigned short crc; /* on 68000 we got an alignment problem,
but this compiler solves it by adding silently
adding a pad byte so data won't fit
and this took about 3h to discover.... */
unsigned char gap1[22]; /* for longword-alignedness (0x4e) */
};
/* crc routines are borrowed from the messydos-handler */
/* excerpt from the messydos-device
; The CRC is computed not only over the actual data, but including
; the SYNC mark (3 * $a1) and the 'ID/DATA - Address Mark' ($fe/$fb).
; As we don't read or encode these fields into our buffers, we have to
; preload the registers containing the CRC with the values they would have
; after stepping over these fields.
;
; How CRCs "really" work:
;
; First, you should regard a bitstring as a series of coefficients of
; polynomials. We calculate with these polynomials in modulo-2
; arithmetic, in which both add and subtract are done the same as
; exclusive-or. Now, we modify our data (a very long polynomial) in
; such a way that it becomes divisible by the CCITT-standard 16-bit
; 16 12 5
; polynomial: x + x + x + 1, represented by $11021. The easiest
; way to do this would be to multiply (using proper arithmetic) our
; datablock with $11021. So we have:
; data * $11021 =
; data * ($10000 + $1021) =
; data * $10000 + data * $1021
; The left part of this is simple: Just add two 0 bytes. But then
; the right part (data $1021) remains difficult and even could have
; a carry into the left part. The solution is to use a modified
; multiplication, which has a result that is not correct, but with
; a difference of any multiple of $11021. We then only need to keep
; the 16 least significant bits of the result.
;
; The following algorithm does this for us:
;
; unsigned char *data, c, crclo, crchi;
; while (not done) {
; c = *data++ + crchi;
; crchi = (@ c) >> 8 + crclo;
; crclo = @ c;
; }
;
; Remember, + is done with EOR, the @ operator is in two tables (high
; and low byte separately), which is calculated as
;
; $1021 * (c & $F0)
; xor $1021 * (c & $0F)
; xor $1021 * (c >> 4) (* is regular multiplication)
;
;
; Anyway, the end result is the same as the remainder of the division of
; the data by $11021. I am afraid I need to study theory a bit more...
my only works was to code this from manx to C....
*/
static ushort dos_crc(void * data_a3, int data_d0, int data_d1, int data_d3)
{
static unsigned char CRCTable1[] = {
0x00,0x10,0x20,0x30,0x40,0x50,0x60,0x70,0x81,0x91,0xa1,0xb1,0xc1,0xd1,0xe1,0xf1,
0x12,0x02,0x32,0x22,0x52,0x42,0x72,0x62,0x93,0x83,0xb3,0xa3,0xd3,0xc3,0xf3,0xe3,
0x24,0x34,0x04,0x14,0x64,0x74,0x44,0x54,0xa5,0xb5,0x85,0x95,0xe5,0xf5,0xc5,0xd5,
0x36,0x26,0x16,0x06,0x76,0x66,0x56,0x46,0xb7,0xa7,0x97,0x87,0xf7,0xe7,0xd7,0xc7,
0x48,0x58,0x68,0x78,0x08,0x18,0x28,0x38,0xc9,0xd9,0xe9,0xf9,0x89,0x99,0xa9,0xb9,
0x5a,0x4a,0x7a,0x6a,0x1a,0x0a,0x3a,0x2a,0xdb,0xcb,0xfb,0xeb,0x9b,0x8b,0xbb,0xab,
0x6c,0x7c,0x4c,0x5c,0x2c,0x3c,0x0c,0x1c,0xed,0xfd,0xcd,0xdd,0xad,0xbd,0x8d,0x9d,
0x7e,0x6e,0x5e,0x4e,0x3e,0x2e,0x1e,0x0e,0xff,0xef,0xdf,0xcf,0xbf,0xaf,0x9f,0x8f,
0x91,0x81,0xb1,0xa1,0xd1,0xc1,0xf1,0xe1,0x10,0x00,0x30,0x20,0x50,0x40,0x70,0x60,
0x83,0x93,0xa3,0xb3,0xc3,0xd3,0xe3,0xf3,0x02,0x12,0x22,0x32,0x42,0x52,0x62,0x72,
0xb5,0xa5,0x95,0x85,0xf5,0xe5,0xd5,0xc5,0x34,0x24,0x14,0x04,0x74,0x64,0x54,0x44,
0xa7,0xb7,0x87,0x97,0xe7,0xf7,0xc7,0xd7,0x26,0x36,0x06,0x16,0x66,0x76,0x46,0x56,
0xd9,0xc9,0xf9,0xe9,0x99,0x89,0xb9,0xa9,0x58,0x48,0x78,0x68,0x18,0x08,0x38,0x28,
0xcb,0xdb,0xeb,0xfb,0x8b,0x9b,0xab,0xbb,0x4a,0x5a,0x6a,0x7a,0x0a,0x1a,0x2a,0x3a,
0xfd,0xed,0xdd,0xcd,0xbd,0xad,0x9d,0x8d,0x7c,0x6c,0x5c,0x4c,0x3c,0x2c,0x1c,0x0c,
0xef,0xff,0xcf,0xdf,0xaf,0xbf,0x8f,0x9f,0x6e,0x7e,0x4e,0x5e,0x2e,0x3e,0x0e,0x1e
};
static unsigned char CRCTable2[] = {
0x00,0x21,0x42,0x63,0x84,0xa5,0xc6,0xe7,0x08,0x29,0x4a,0x6b,0x8c,0xad,0xce,0xef,
0x31,0x10,0x73,0x52,0xb5,0x94,0xf7,0xd6,0x39,0x18,0x7b,0x5a,0xbd,0x9c,0xff,0xde,
0x62,0x43,0x20,0x01,0xe6,0xc7,0xa4,0x85,0x6a,0x4b,0x28,0x09,0xee,0xcf,0xac,0x8d,
0x53,0x72,0x11,0x30,0xd7,0xf6,0x95,0xb4,0x5b,0x7a,0x19,0x38,0xdf,0xfe,0x9d,0xbc,
0xc4,0xe5,0x86,0xa7,0x40,0x61,0x02,0x23,0xcc,0xed,0x8e,0xaf,0x48,0x69,0x0a,0x2b,
0xf5,0xd4,0xb7,0x96,0x71,0x50,0x33,0x12,0xfd,0xdc,0xbf,0x9e,0x79,0x58,0x3b,0x1a,
0xa6,0x87,0xe4,0xc5,0x22,0x03,0x60,0x41,0xae,0x8f,0xec,0xcd,0x2a,0x0b,0x68,0x49,
0x97,0xb6,0xd5,0xf4,0x13,0x32,0x51,0x70,0x9f,0xbe,0xdd,0xfc,0x1b,0x3a,0x59,0x78,
0x88,0xa9,0xca,0xeb,0x0c,0x2d,0x4e,0x6f,0x80,0xa1,0xc2,0xe3,0x04,0x25,0x46,0x67,
0xb9,0x98,0xfb,0xda,0x3d,0x1c,0x7f,0x5e,0xb1,0x90,0xf3,0xd2,0x35,0x14,0x77,0x56,
0xea,0xcb,0xa8,0x89,0x6e,0x4f,0x2c,0x0d,0xe2,0xc3,0xa0,0x81,0x66,0x47,0x24,0x05,
0xdb,0xfa,0x99,0xb8,0x5f,0x7e,0x1d,0x3c,0xd3,0xf2,0x91,0xb0,0x57,0x76,0x15,0x34,
0x4c,0x6d,0x0e,0x2f,0xc8,0xe9,0x8a,0xab,0x44,0x65,0x06,0x27,0xc0,0xe1,0x82,0xa3,
0x7d,0x5c,0x3f,0x1e,0xf9,0xd8,0xbb,0x9a,0x75,0x54,0x37,0x16,0xf1,0xd0,0xb3,0x92,
0x2e,0x0f,0x6c,0x4d,0xaa,0x8b,0xe8,0xc9,0x26,0x07,0x64,0x45,0xa2,0x83,0xe0,0xc1,
0x1f,0x3e,0x5d,0x7c,0x9b,0xba,0xd9,0xf8,0x17,0x36,0x55,0x74,0x93,0xb2,0xd1,0xf0
};
/* look at the asm-code - what looks in C a bit strange is almost as good as handmade */
register int i;
register unsigned char *CRCT1, *CRCT2, *data, c, crch, crcl;
CRCT1=CRCTable1;
CRCT2=CRCTable2;
data=data_a3;
crcl=data_d1;
crch=data_d0;
for (i=data_d3; i>=0; i--) {
c = (*data++) ^ crch;
crch = CRCT1[c] ^ crcl;
crcl = CRCT2[c];
}
return (crch<<8)|crcl;
}
static inline ushort dos_hdr_crc (struct dos_header *hdr)
{
return dos_crc(&(hdr->track), 0xb2, 0x30, 3); /* precomputed magic */
}
static inline ushort dos_data_crc(unsigned char *data)
{
return dos_crc(data, 0xe2, 0x95 ,511); /* precomputed magic */
}
static inline unsigned char dos_decode_byte(ushort word)
{
register ushort w2;
register unsigned char byte;
register unsigned char *dec = mfmdecode;