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* grub-core/fs/ext2.c (grub_ext2_read_block): Use shifts rather than

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divisions.
This commit is contained in:
Vladimir 'phcoder' Serbinenko 2013-01-05 18:37:34 +01:00
parent 033d0b4b0b
commit f797ec85a0
2 changed files with 21 additions and 14 deletions
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5
ChangeLog
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@ -1,3 +1,8 @@
2013-01-05 Vladimir Serbinenko <phcoder@gmail.com>
* grub-core/fs/ext2.c (grub_ext2_read_block): Use shifts rather than
divisions.
2013-01-05 Vladimir Serbinenko <phcoder@gmail.com> 2013-01-05 Vladimir Serbinenko <phcoder@gmail.com>
* grub-core/fs/ntfs.c: Eliminate useless divisions in favor of shifts. * grub-core/fs/ntfs.c: Eliminate useless divisions in favor of shifts.

30
grub-core/fs/ext2.c
View file

@ -454,11 +454,12 @@ grub_ext2_read_block (grub_fshelp_node_t node, grub_disk_addr_t fileblock)
blknr = grub_le_to_cpu32 (indir[fileblock - INDIRECT_BLOCKS]); blknr = grub_le_to_cpu32 (indir[fileblock - INDIRECT_BLOCKS]);
} }
/* Double indirect. */ /* Double indirect. */
else if (fileblock < INDIRECT_BLOCKS + blksz / 4 * (blksz / 4 + 1)) else if (fileblock < INDIRECT_BLOCKS
+ blksz / 4 * ((grub_disk_addr_t) blksz / 4 + 1))
{ {
unsigned int perblock = blksz / 4; int log_perblock = log2_blksz + 9 - 2;
unsigned int rblock = fileblock - (INDIRECT_BLOCKS grub_disk_addr_t rblock = fileblock - (INDIRECT_BLOCKS
+ blksz / 4); + blksz / 4);
grub_uint32_t indir[blksz / 4]; grub_uint32_t indir[blksz / 4];
if (grub_disk_read (data->disk, if (grub_disk_read (data->disk,
@ -470,21 +471,22 @@ grub_ext2_read_block (grub_fshelp_node_t node, grub_disk_addr_t fileblock)
if (grub_disk_read (data->disk, if (grub_disk_read (data->disk,
((grub_disk_addr_t) ((grub_disk_addr_t)
grub_le_to_cpu32 (indir[rblock / perblock])) grub_le_to_cpu32 (indir[rblock >> log_perblock]))
<< log2_blksz, << log2_blksz,
0, blksz, indir)) 0, blksz, indir))
return grub_errno; return grub_errno;
blknr = grub_le_to_cpu32 (indir[rblock % perblock]); blknr = grub_le_to_cpu32 (indir[rblock & ((1 << log_perblock) - 1)]);
} }
/* triple indirect. */ /* triple indirect. */
else if (fileblock < INDIRECT_BLOCKS + blksz / 4 * (blksz / 4 + 1) else if (fileblock < INDIRECT_BLOCKS + blksz / 4 * ((grub_disk_addr_t) blksz / 4 + 1)
+ (blksz / 4) * (blksz / 4) * (blksz / 4 + 1)) + ((grub_disk_addr_t) blksz / 4) * ((grub_disk_addr_t) blksz / 4)
* ((grub_disk_addr_t) blksz / 4 + 1))
{ {
unsigned int perblock = blksz / 4; int log_perblock = log2_blksz + 9 - 2;
unsigned int rblock = fileblock - (INDIRECT_BLOCKS + blksz / 4 grub_disk_addr_t rblock = fileblock - (INDIRECT_BLOCKS + blksz / 4
* (blksz / 4 + 1)); * (blksz / 4 + 1));
grub_uint32_t indir[blksz / 4]; grub_uint32_t indir[blksz / 4];
if (grub_disk_read (data->disk, if (grub_disk_read (data->disk,
@ -496,19 +498,19 @@ grub_ext2_read_block (grub_fshelp_node_t node, grub_disk_addr_t fileblock)
if (grub_disk_read (data->disk, if (grub_disk_read (data->disk,
((grub_disk_addr_t) ((grub_disk_addr_t)
grub_le_to_cpu32 (indir[(rblock / perblock) / perblock])) grub_le_to_cpu32 (indir[(rblock >> log_perblock) >> log_perblock]))
<< log2_blksz, << log2_blksz,
0, blksz, indir)) 0, blksz, indir))
return grub_errno; return grub_errno;
if (grub_disk_read (data->disk, if (grub_disk_read (data->disk,
((grub_disk_addr_t) ((grub_disk_addr_t)
grub_le_to_cpu32 (indir[(rblock / perblock) % perblock])) grub_le_to_cpu32 (indir[(rblock >> log_perblock) & ((1 << log_perblock) - 1)]))
<< log2_blksz, << log2_blksz,
0, blksz, indir)) 0, blksz, indir))
return grub_errno; return grub_errno;
blknr = grub_le_to_cpu32 (indir[rblock % perblock]); blknr = grub_le_to_cpu32 (indir[rblock & ((1 << log_perblock) - 1)]);
} }
else else
{ {