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

	divisions.

diff --git a/ChangeLog b/ChangeLog
index 88fd76309ec2f809b25a1c6c8f07eccd44ddc1af..af2916120b0408e6be3cda221526949d7c137c0f 100644 (file)
--- a/ChangeLog
+++ b/ChangeLog
@@ -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>
 
        * 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 bd1ab24380d4a005256d954c6e13d1b3562b7ce4..cf2e2f47d45c6357a317b37305a80f71624795ef 100644 (file)
--- 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
     {