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authorH. Peter Anvin <hpa@zytor.com>2007-07-11 16:38:30 -0700
committerH. Peter Anvin <hpa@zytor.com>2007-07-11 16:38:30 -0700
commitea75b2912f47ccfd922a2399fe8a7dfdb793f26a (patch)
tree0cca0ccbb0f7d56d3a36fc2d0c019826800b025f /mbr/mbr.S
parent9137770dd9710f802dd4ace76d85e8b976dc791b (diff)
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Another 12 bytes shaved off the MBR...
Diffstat (limited to 'mbr/mbr.S')
-rw-r--r--mbr/mbr.S30
1 files changed, 12 insertions, 18 deletions
diff --git a/mbr/mbr.S b/mbr/mbr.S
index 654393fd..2756d7d0 100644
--- a/mbr/mbr.S
+++ b/mbr/mbr.S
@@ -111,28 +111,33 @@ next:
*/
read_sector:
pushal
-read_sector_cbios:
+ movw %sp, %si
xorl %edx, %edx
+ movw $bootsec, %bx
+read_sector_cbios:
divl (secpercyl)
- rorb %ah
- rorb %ah
+ shlb $6, %ah
movb %ah, %cl
movb %al, %ch
- movw %dx, %ax
+ xchgw %dx, %ax
divb (sectors)
movb %al, %dh
incb %ah
orb %ah, %cl
- movw $bootsec, %bx
movw $0x0201, %ax
jmp read_common
read_sector_ebios:
- movw $dapa, %si
- movl %eax, 8(%si)
+ pushl %edx /* MSW of LBA */
+ pushl %eax /* LSW of LBA */
+ pushw %es /* Buffer segment */
+ pushw %bx /* Buffer offset */
+ pushw $1 /* Sector count */
+ pushw $16 /* Size of packet */
movb $0x42, %ah
read_common:
movb (driveno), %dl
int $0x13
+ movw %si, %sp
popal
ret
@@ -286,14 +291,3 @@ disk_error_msg:
too_many_active_msg:
.ascii "Multiple active partitions."
.byte 0
-
-#ifndef NO_ALIGN
- .balign 4
-#endif
-dapa:
- .short 16 /* Size of packet */
- .short 1 /* Sector count */
- .short 0x7c00 /* Buffer offset */
- .short 0 /* Buffer segment */
- .long 0 /* LSW of LBA */
- .long 0 /* MSW of LBA */