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| author | Frediano Ziglio <frediano.ziglio@citrix.com> | 2013-02-08 12:58:34 +0000 |
|---|---|---|
| committer | Matt Fleming <matt.fleming@intel.com> | 2013-02-11 12:35:12 +0000 |
| commit | b681bd70ac5c478c2d450aa1db98aa9359625a7d (patch) | |
| tree | 5e9d4b48c87854fc6ccd8781aa63fa95a47bed73 | |
| parent | 71a16643953b812d7054784c3f7f0f03cf116264 (diff) | |
| download | syslinux-b681bd70ac5c478c2d450aa1db98aa9359625a7d.tar.gz syslinux-b681bd70ac5c478c2d450aa1db98aa9359625a7d.tar.xz syslinux-b681bd70ac5c478c2d450aa1db98aa9359625a7d.zip | |
4k_sector: Save some bytes adding a function to set bx before read_sector
Mostly of the time bx was set as phdr before calling read_sector
so add a specific function to set %bx and call read_sector
gaining 2 bytes
Signed-off-by: Frediano Ziglio <frediano.ziglio@citrix.com>
Signed-off-by: Matt Fleming <matt.fleming@intel.com>
| -rw-r--r-- | mbr/gptmbr.S | 13 |
1 files changed, 7 insertions, 6 deletions
diff --git a/mbr/gptmbr.S b/mbr/gptmbr.S index ef2235db..b9c0777c 100644 --- a/mbr/gptmbr.S +++ b/mbr/gptmbr.S @@ -118,14 +118,11 @@ next: xorl %eax,%eax cltd incw %ax /* %edx:%eax = 1 */ - movw $phdr, %bx - pushw %bx /* -8(%bp) phdr == bootsect */ - call read_sector + call read_sector_phdr /* Number of partition sectors */ /* We assume the partition table is 32K or less, and that the sector size is 512. */ - /* Note: phdr == 6(%bp) */ movw (80+6)(%bp),%cx /* NumberOfPartitionEntries */ movw (84+6)(%bp),%ax /* SizeOfPartitionEntry */ pushw %ax @@ -215,8 +212,7 @@ found_part: boot: movl (32+20)(%si),%eax movl (36+20)(%si),%edx - popw %bx - call read_sector + call read_sector_phdr cmpw $0xaa55, -2(%bx) jne missing_os /* Not a valid boot sector */ movw %bp, %sp /* driveno == bootsec-6 */ @@ -238,6 +234,11 @@ saturate_stosl: 1: stosl ret +read_sector_phdr: + movw $phdr, %bx + + /* fall through and read sector */ + /* * read_sector: read a single sector pointed to by %edx:%eax to * %es:%bx. CF is set on error. All registers saved. |