From: H. Peter Anvin <hpa@zytor.com>
Date: Tue, 12 Feb 2008 02:35:41 +0000 (-0800)
Subject: shuffle: avoid computing block lists that will never converge
X-Git-Tag: syslinux-3.62-pre2~4
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=8d419fbcb295fcd8ee54cc5c95326a8da9959f80;p=profile%2Fivi%2Fsyslinux.git

shuffle: avoid computing block lists that will never converge

It is safe to assume that the number of moves will never decrease as
the reserved memory space increases; thus, no need to do individual
increments; skip ahead.
---

diff --git a/com32/lib/syslinux/shuffle.c b/com32/lib/syslinux/shuffle.c
index 3393f2a..dcb8d31 100644
--- a/com32/lib/syslinux/shuffle.c
+++ b/com32/lib/syslinux/shuffle.c
@@ -64,7 +64,7 @@ int syslinux_prepare_shuffle(struct syslinux_movelist *fraglist,
   struct syslinux_memmap *rxmap = NULL, *ml;
   struct shuffle_descriptor *dp, *dbuf;
   int np, nb, rv = -1;
-  int desc_blocks;
+  int desc_blocks, need_blocks;
   addr_t desczone, descfree, descaddr, descoffs;
   int nmoves, nzero;
   struct shuffle_descriptor primaries[2];
@@ -87,8 +87,8 @@ int syslinux_prepare_shuffle(struct syslinux_movelist *fraglist,
 
   dprintf("desczone = 0x%08x, descfree = 0x%08x\n", desczone, descfree);
 
-  for (desc_blocks = (nzero+DESC_BLOCK_SIZE)/(DESC_BLOCK_SIZE-1) ; ;
-       desc_blocks++) {
+  desc_blocks = (nzero+DESC_BLOCK_SIZE)/(DESC_BLOCK_SIZE-1);
+  for (;;) {
     addr_t descmem = desc_blocks*
       sizeof(struct shuffle_descriptor)*DESC_BLOCK_SIZE;
 
@@ -110,8 +110,12 @@ int syslinux_prepare_shuffle(struct syslinux_movelist *fraglist,
     for (mp = moves; mp; mp = mp->next)
       nmoves++;
 
-    if ((nmoves+nzero) <= desc_blocks*(DESC_BLOCK_SIZE-1))
+    need_blocks = (nmoves+nzero)/(DESC_BLOCK_SIZE-1);
+
+    if (desc_blocks >= need_blocks)
       break;			/* Sufficient memory, yay */
+
+    desc_blocks = need_blocks;	/* Try again... */
   }
 
 #if DEBUG