diff options
Diffstat (limited to 'bootsect.S')
| -rw-r--r-- | bootsect.S | 54 |
1 files changed, 27 insertions, 27 deletions
@@ -5,7 +5,7 @@ * itself out of the way to address 0x90000, and jumps there.
*
* It then loads 'setup' directly after itself (0x90200), and the system
- * at 0x10000, using BIOS interrupts.
+ * at 0x10000, using BIOS interrupts.
*
* The loader has been made as simple as possible, and continuos
* read errors will result in a unbreakable loop. Reboot by hand. It
@@ -17,7 +17,7 @@ #include "defs.h"
ROOT_DEV = 0
-
+
.code16
.section ".bootsect", "ax", @progbits
_boot:
@@ -38,7 +38,7 @@ _main: movsw
ljmp $INITSEG, $go - _boot
-go:
+go:
movw %cs, %ax
movw $(0x4000-12), %dx # 0x4000 is arbitrary value >= length of
# bootsect + length of setup + room for stack
@@ -54,9 +54,9 @@ go: movw %ax, %es
movw %ax, %ss # put stack at INITSEG:0x4000-12.
movw %dx, %sp
-
+
/*
- * Many BIOS's default disk parameter tables will not
+ * Many BIOS's default disk parameter tables will not
* recognize multi-sector reads beyond the maximum sector number
* specified in the default diskette parameter tables - this may
* mean 7 sectors in some cases.
@@ -64,7 +64,7 @@ go: * Since single sector reads are slow and out of the question,
* we must take care of this by creating new parameter tables
* (for the first disk) in RAM. We will set the maximum sector
- * count to 18 - the most we will encounter on an HD 1.44.
+ * count to 18 - the most we will encounter on an HD 1.44.
*
* High doesn't hurt. Low does.
*
@@ -92,10 +92,10 @@ go: movw %ax, %fs
movw %ax, %gs
- xorb %ah, %ah # reset FDC
+ xorb %ah, %ah # reset FDC
xorb %dl, %dl
int $0x13
-
+
# load the setup-sectors directly after the bootblock.
# Note that 'es' is already set up.
@@ -112,7 +112,7 @@ load_setup: call print_nl
movw %sp, %bp
call print_hex
- popw %ax
+ popw %ax
xorb %dl, %dl # reset FDC
xorb %ah, %ah
@@ -140,7 +140,7 @@ ok_load_setup: int $0x13
jnc got_sectors
movb $0x09, %cl
-
+
got_sectors:
movw %cx, %cs:sectors - _boot
movw $INITSEG, %ax
@@ -151,13 +151,13 @@ got_sectors: movb $0x03, %ah # read cursor pos
xorb %bh, %bh
int $0x10
-
+
movw $9, %cx
movw $0x0007, %bx # page 0, attribute 7 (normal)
movw $msg1 - _boot, %bp
movw $0x1301, %ax # write string, move cursor
int $0x10
-
+
# ok, we've written the message, now
# we want to load the system (at 0x10000)
@@ -186,7 +186,7 @@ track: .word 0 # current track read_it:
movw %es, %ax
testw $0x0fff, %ax
-die:
+die:
jne die # es must be at 64kB boundary
xorw %bx,%bx # bx is starting address within segment
rp_read:
@@ -229,7 +229,7 @@ ok3_read: movw %ax, %es
xorw %bx, %bx
jmp rp_read
-
+
read_track:
pusha
pusha
@@ -237,7 +237,7 @@ read_track: movw $7, %bx
int $0x10
popa
-
+
movw track - _boot, %dx
movw sread - _boot, %cx
incw %cx
@@ -246,7 +246,7 @@ read_track: movb %dl, %dh
andw $0x0100, %dx
movb $2, %ah
-
+
pushw %dx # save for error dump
pushw %cx
pushw %bx
@@ -258,23 +258,23 @@ read_track: popa
ret
-bad_rt:
+bad_rt:
pushw %ax # save error code
call print_all # ah = error, al = read
-
+
xorb %ah, %ah
xorb %dl, %dl
int $0x13
addw $10, %sp
- popa
+ popa
jmp read_track
/*
- * print_all is for debugging purposes.
+ * print_all is for debugging purposes.
* It will print out all of the registers. The assumption is that this is
* called from a routine, with a stack frame like
- * dx
+ * dx
* cx
* bx
* ax
@@ -282,7 +282,7 @@ bad_rt: * ret <- sp
*
*/
-
+
print_all:
movw $5, %cx # error code + 4 registers
movw %sp, %bp
@@ -299,7 +299,7 @@ print_loop: int $0x10
movb $'X', %al
int $0x10
- movb $':', %al
+ movb $':', %al
int $0x10
no_reg:
@@ -308,18 +308,18 @@ no_reg: popw %cx
loop print_loop
ret
-
+
print_nl:
movw $0xe0d, %ax # CR
int $0x10
movb $0x0a, %al # LF
int $0x10
ret
-
+
/*
* print_hex is for debugging purposes, and prints the word
* pointed to by ss:bp in hexadecmial.
-*/
+ */
print_hex:
movw $4, %cx # 4 hex digits
@@ -334,7 +334,7 @@ print_digit: cmpb $'9', %al # check for overflow
jbe good_digit
addb $('A' - '0' - 10), %al
-
+
good_digit:
int $0x10
loop print_digit
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