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/* Created (MFS based):
* February 2010 (Evgeniy Ivanov)
*/
#include "fs.h"
#include "buf.h"
#include "inode.h"
#include "super.h"
/*===========================================================================*
* get_block *
*===========================================================================*/
struct buf *get_block(dev_t dev, block_t block, int how)
{
/* Wrapper routine for lmfs_get_block(). This ext2 implementation does not deal
* well with block read errors pretty much anywhere. To prevent corruption due
* to unchecked error conditions, we panic upon an I/O failure here.
*/
struct buf *bp;
int r;
if ((r = lmfs_get_block(&bp, dev, block, how)) != OK && r != ENOENT)
panic("ext2: error getting block (%llu,%u): %d", dev, block, r);
assert(r == OK || how == PEEK);
return (r == OK) ? bp : NULL;
}
/*===========================================================================*
* conv2 *
*===========================================================================*/
unsigned conv2(norm, w)
int norm; /* TRUE if no swap, FALSE for byte swap */
int w; /* promotion of 16-bit word to be swapped */
{
/* Possibly swap a 16-bit word between 8086 and 68000 byte order. */
if (norm) return( (unsigned) w & 0xFFFF);
return( ((w&BYTE) << 8) | ( (w>>8) & BYTE));
}
/*===========================================================================*
* conv4 *
*===========================================================================*/
long conv4(norm, x)
int norm; /* TRUE if no swap, FALSE for byte swap */
long x; /* 32-bit long to be byte swapped */
{
/* Possibly swap a 32-bit long between 8086 and 68000 byte order. */
unsigned lo, hi;
long l;
if (norm) return(x); /* byte order was already ok */
lo = conv2(FALSE, (int) x & 0xFFFF); /* low-order half, byte swapped */
hi = conv2(FALSE, (int) (x>>16) & 0xFFFF); /* high-order half, swapped */
l = ( (long) lo <<16) | hi;
return(l);
}
/*===========================================================================*
* ansi_strcmp *
*===========================================================================*/
int ansi_strcmp(register const char* ansi_s, register const char *s2,
register size_t ansi_s_length)
{
/* Compare non null-terminated string ansi_s (length=ansi_s_length)
* with C-string s2.
* It returns 0 if strings are equal, otherwise -1 is returned.
*/
if (ansi_s_length) {
do {
if (*s2 == '\0')
return -1;
if (*ansi_s++ != *s2++)
return -1;
} while (--ansi_s_length > 0);
if (*s2 == '\0')
return 0;
else
return -1;
}
return 0;
}
/*===========================================================================*
* setbit *
*===========================================================================*/
bit_t setbit(bitchunk_t *bitmap, bit_t max_bits, unsigned int word)
{
/* Find free bit in bitmap and set. Return number of the bit,
* if failed return -1.
*/
bitchunk_t *wptr, *wlim;
bit_t b = -1;
/* TODO: do we need to add 1? I saw a situation, when it was
* required, and since we check bit number with max_bits it
* should be safe.
*/
wlim = &bitmap[FS_BITMAP_CHUNKS(max_bits >> 3)];
/* Iterate over the words in block. */
for (wptr = &bitmap[word]; wptr < wlim; wptr++) {
bit_t i;
bitchunk_t k;
/* Does this word contain a free bit? */
if (*wptr == (bitchunk_t) ~0)
continue;
/* Find and allocate the free bit. */
k = (int) *wptr;
for (i = 0; (k & (1 << i)) != 0; ++i) {}
/* Bit number from the start of the bit map. */
b = (wptr - &bitmap[0]) * FS_BITCHUNK_BITS + i;
/* Don't allocate bits beyond the end of the map. */
if (b >= max_bits) {
b = -1;
continue;
}
/* Allocate bit number. */
k |= 1 << i;
*wptr = (int) k;
break;
}
return b;
}
/*===========================================================================*
* setbyte *
*===========================================================================*/
bit_t setbyte(bitchunk_t *bitmap, bit_t max_bits)
{
/* Find free byte in bitmap and set it. Return number of the starting bit,
* if failed return -1.
*/
unsigned char *wptr, *wlim;
bit_t b = -1;
wptr = (unsigned char*) &bitmap[0];
/* TODO: do we need to add 1? I saw a situation, when it was
* required, and since we check bit number with max_bits it
* should be safe.
*/
wlim = &wptr[(max_bits >> 3)];
/* Iterate over the words in block. */
for ( ; wptr < wlim; wptr++) {
/* Is it a free byte? */
if (*wptr | 0)
continue;
/* Bit number from the start of the bit map. */
b = (wptr - (unsigned char*) &bitmap[0]) * CHAR_BIT;
/* Don't allocate bits beyond the end of the map. */
if (b + CHAR_BIT >= max_bits) {
b = -1;
continue;
}
/* Allocate byte number. */
*wptr = (unsigned char) ~0;
break;
}
return b;
}
/*===========================================================================*
* unsetbit *
*===========================================================================*/
int unsetbit(bitchunk_t *bitmap, bit_t bit)
{
/* Unset specified bit. If requested bit is already free return -1,
* otherwise return 0.
*/
unsigned int word; /* bit_returned word in bitmap */
bitchunk_t k, mask;
word = bit / FS_BITCHUNK_BITS;
bit = bit % FS_BITCHUNK_BITS; /* index in word */
mask = 1 << bit;
k = (int) bitmap[word];
if (!(k & mask))
return -1;
k &= ~mask;
bitmap[word] = (int) k;
return 0;
}
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