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#include <stdio.h>
#include "msdos.h"
extern int fd, dir_start, num_fat, fat_len, fat_error, fat_bits;
extern unsigned char *fat_buf;
/*
* Puts a code into the FAT table. Is the opposite of fat_decode(). No
* sanity checking is done on the code. Returns a 1 on error.
*/
int
fat_encode(num, code)
unsigned int num;
unsigned int code;
{
unsigned int start;
if (fat_bits == 12) {
/*
* | byte n | byte n+1 | byte n+2 |
* |7|6|5|4|3|2|1|0|7|6|5|4|3|2|1|0|7|6|5|4|3|2|1|0|
* | | | | | | | | | | | | | | | | | | | | | | | | |
* | n+0.0 | n+0.5 | n+1.0 | n+1.5 | n+2.0 | n+2.5 |
* \_____ \____ \______/________/_____ /
* ____\______\________/ _____/ ____\_/
* / \ \ / / \
* | n+1.5 | n+0.0 | n+0.5 | n+2.0 | n+2.5 | n+1.0 |
* | FAT entry k | FAT entry k+1 |
*/
/* which bytes contain the entry */
start = num * 3 / 2;
if (start <= 2 || start + 1 > (fat_len * MSECTOR_SIZE))
return(1);
/* (odd) not on byte boundary */
if (num % 2) {
*(fat_buf + start) = (*(fat_buf + start) & 0x0f) + ((code << 4) & 0xf0);
*(fat_buf + start + 1) = (code >> 4) & 0xff;
}
/* (even) on byte boundary */
else {
*(fat_buf + start) = code & 0xff;
*(fat_buf + start + 1) = (*(fat_buf + start + 1) & 0xf0) + ((code >> 8) & 0x0f);
}
}
else {
/*
* | byte n | byte n+1 |
* |7|6|5|4|3|2|1|0|7|6|5|4|3|2|1|0|
* | | | | | | | | | | | | | | | | |
* | FAT entry k |
*/
/* which bytes contain the entry */
start = num * 2;
if (start <= 3 || start + 1 > (fat_len * MSECTOR_SIZE))
return(1);
*(fat_buf + start + 1) = code / 0x100;
*(fat_buf + start) = code % 0x100;
}
return(0);
}
/*
* Write the FAT table to the disk. Up to now the FAT manipulation has
* been done in memory. All errors are fatal. (Might not be too smart
* to wait till the end of the program to write the table. Oh well...)
*/
void
fat_write()
{
int i, start, dups;
void disk_write();
if (fd < 0)
return;
start = dir_start - (fat_len * num_fat);
for (i=start; i<start+fat_len; i++)
disk_write((long) i, &fat_buf[(i-start)*MSECTOR_SIZE], MSECTOR_SIZE);
/*
* Only duplicate the FAT table if no errors were detected
*/
if (!fat_error) {
dups = num_fat - 1;
while (dups--) {
start += fat_len;
for (i=start; i<start+fat_len; i++)
disk_write((long) i, &fat_buf[(i-start)*MSECTOR_SIZE], MSECTOR_SIZE);
}
}
return;
}
These are the contents of the former NiCE NeXT User Group NeXTSTEP/OpenStep software archive, currently hosted by Netfuture.ch.