Another 12 bytes shaved off the MBR...

diff --git a/mbr/mbr.S b/mbr/mbr.S
index 654393f..2756d7d 100644 (file)
--- 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 */