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Diffstat (limited to 'mbr')
-rw-r--r--mbr/mbr.S32
1 files changed, 16 insertions, 16 deletions
diff --git a/mbr/mbr.S b/mbr/mbr.S
index ea74a86a..b512c119 100644
--- a/mbr/mbr.S
+++ b/mbr/mbr.S
@@ -98,9 +98,8 @@ next:
mulw %cx /* Heads*sectors -> sectors per cylinder */
pushw %ax /* Save sectors/cylinder on the stack */
- xorl %eax, %eax
- pushl %eax /* Base */
- pushl %eax /* Root */
+ xorl %eax, %eax /* Base */
+ xorl %edx, %edx /* Root: %edx <- 0 */
call scan_partition_table
/* If we get here, we have no OS */
@@ -158,15 +157,19 @@ read_partition_table:
/*
* scan_partition_table:
* Scan a partition table currently loaded in the partition table
- * area. Preserve 16-bit registers.
+ * area. Preserve all registers.
*
- * On stack:
- * 18(%bp) - root (offset from MBR, or 0 for MBR)
- * 22(%bp) - base (location of this partition table)
+ * On entry:
+ * %eax - base (location of this partition table)
+ * %edx - root (offset from MBR, or 0 for MBR)
+ *
+ * These get pushed into stack slots:
+ * 28(%bp) - %eax - base
+ * 20(%bp) - %edx - root
*/
scan_partition_table:
- pusha
+ pushal
movw %sp, %bp
/* Search for active partitions */
@@ -175,7 +178,7 @@ scan_partition_table:
xorw %ax, %ax
5:
testb $0x80, (%di)
- jz 6f
+ jz 6f
incw %ax
movw %di, %si
6:
@@ -203,21 +206,18 @@ scan_partition_table:
partition table and resume scan. */
8:
movl 8(%di), %eax /* Partition table offset */
- movl 18(%bp), %edx /* "Root" */
+ movl 20(%bp), %edx /* "Root" */
addl %edx, %eax /* Compute location of new ptab */
andl %edx, %edx /* Is this the MBR? */
jnz 10f
movl %eax, %edx /* Offset -> root if this was MBR */
10:
- pushl %eax /* Push new base */
- pushl %edx /* Push new root */
call read_partition_table
- jc 11f
+ jc 11f
call scan_partition_table
11:
- addw $8, %sp
/* This returned, so we need to reload the current partition table */
- movl 22(%bp), %eax
+ movl 28(%bp), %eax
call read_partition_table
/* fall through */
@@ -227,7 +227,7 @@ scan_partition_table:
loopw 7b
/* Nothing found, return */
- popa
+ popal
ret
/*