From f797ec85a02c0137a739fba7ee3f40d063bb7ade Mon Sep 17 00:00:00 2001 From: Vladimir 'phcoder' Serbinenko Date: Sat, 5 Jan 2013 18:37:34 +0100 Subject: [PATCH] * grub-core/fs/ext2.c (grub_ext2_read_block): Use shifts rather than divisions. --- ChangeLog | 5 +++++ grub-core/fs/ext2.c | 30 ++++++++++++++++-------------- 2 files changed, 21 insertions(+), 14 deletions(-) diff --git a/ChangeLog b/ChangeLog index 88fd76309..af2916120 100644 --- a/ChangeLog +++ b/ChangeLog @@ -1,3 +1,8 @@ +2013-01-05 Vladimir Serbinenko + + * grub-core/fs/ext2.c (grub_ext2_read_block): Use shifts rather than + divisions. + 2013-01-05 Vladimir Serbinenko * grub-core/fs/ntfs.c: Eliminate useless divisions in favor of shifts. diff --git a/grub-core/fs/ext2.c b/grub-core/fs/ext2.c index bd1ab2438..cf2e2f47d 100644 --- a/grub-core/fs/ext2.c +++ b/grub-core/fs/ext2.c @@ -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]); } /* 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; - unsigned int rblock = fileblock - (INDIRECT_BLOCKS - + blksz / 4); + int log_perblock = log2_blksz + 9 - 2; + grub_disk_addr_t rblock = fileblock - (INDIRECT_BLOCKS + + blksz / 4); grub_uint32_t indir[blksz / 4]; 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, ((grub_disk_addr_t) - grub_le_to_cpu32 (indir[rblock / perblock])) + grub_le_to_cpu32 (indir[rblock >> log_perblock])) << log2_blksz, 0, blksz, indir)) return grub_errno; - blknr = grub_le_to_cpu32 (indir[rblock % perblock]); + blknr = grub_le_to_cpu32 (indir[rblock & ((1 << log_perblock) - 1)]); } /* triple indirect. */ - else if (fileblock < INDIRECT_BLOCKS + blksz / 4 * (blksz / 4 + 1) - + (blksz / 4) * (blksz / 4) * (blksz / 4 + 1)) + else if (fileblock < INDIRECT_BLOCKS + blksz / 4 * ((grub_disk_addr_t) 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; - unsigned int rblock = fileblock - (INDIRECT_BLOCKS + blksz / 4 - * (blksz / 4 + 1)); + int log_perblock = log2_blksz + 9 - 2; + grub_disk_addr_t rblock = fileblock - (INDIRECT_BLOCKS + blksz / 4 + * (blksz / 4 + 1)); grub_uint32_t indir[blksz / 4]; 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, ((grub_disk_addr_t) - grub_le_to_cpu32 (indir[(rblock / perblock) / perblock])) + grub_le_to_cpu32 (indir[(rblock >> log_perblock) >> log_perblock])) << log2_blksz, 0, blksz, indir)) return grub_errno; if (grub_disk_read (data->disk, ((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, 0, blksz, indir)) return grub_errno; - blknr = grub_le_to_cpu32 (indir[rblock % perblock]); + blknr = grub_le_to_cpu32 (indir[rblock & ((1 << log_perblock) - 1)]); } else {