[syslinux:pathbased] gptmbr: save four bytes

[syslinux-bot for H. Peter Anvin]

Commit-ID:  92d1d619c033353a5e532b7118daee1a403f08ca
Gitweb:     http://syslinux.zytor.com/commit/92d1d619c033353a5e532b7118daee1a403f08ca
Author:     H. Peter Anvin <hpa at linux.intel.com>
AuthorDate: Fri, 11 Jun 2010 17:21:35 -0700
Committer:  H. Peter Anvin <hpa at linux.intel.com>
CommitDate: Fri, 11 Jun 2010 17:21:35 -0700

gptmbr: save four bytes

Save four bytes by observing that none of our code relies on
saturate_stosl not actually corrupting %eax.

Signed-off-by: H. Peter Anvin <hpa at linux.intel.com>


---
 mbr/gptmbr.S |    9 +++++++--
 1 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/mbr/gptmbr.S b/mbr/gptmbr.S
index 42887db..e8c60c0 100644
--- a/mbr/gptmbr.S
+++ b/mbr/gptmbr.S
@@ -222,15 +222,20 @@ boot:
 	cli
 	jmpw	*%sp		/* %sp == bootsec */
 
+/*
+ * Store the value in %eax to %di iff %edx == 0, otherwise store -1.
+ * Returns the value that was actually written in %eax.
+ */
 saturate_stosl:
-	pushl	%eax
 	andl	%edx,%edx
 	jz 1f
 	orl	$-1,%eax
 1:	stosl
-	popl	%eax
 	ret
 
+/*
+ * Increment %edx:%eax
+ */
 inc64:
 	addl	$1,%eax
 	adcl	$0,%edx