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Saved a few bytes by omitting frame pointers, using byte-sized

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instructions more (many cases were already intended to be byte-sized
but were missing prefixes so gas assembled them bogusly), and
rearranging a loop to test at the end.
This commit is contained in:
Bruce Evans 1997-07-13 15:24:15 +00:00
parent 28596d2346
commit 5f0539ec6c
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=27373
1 changed files with 14 additions and 31 deletions
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45
sys/i386/boot/biosboot/serial.S
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@ -24,7 +24,7 @@
* the rights to redistribute these changes.
*
* from: Mach, Revision 2.2 92/04/04 11:34:26 rpd
* $Id: serial.S,v 1.7 1997/05/16 10:40:00 bde Exp $
* $Id: serial.S,v 1.8 1997/06/09 05:10:55 bde Exp $
*/
/*
@ -67,8 +67,9 @@ WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
.file "serial.s"
#include <i386/isa/sioreg.h>
#include "asm.h"
#include "../../isa/sioreg.h"
.text
/*
@ -91,25 +92,21 @@ WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
ENTRY(serial_putc)
push %ebp
mov %esp, %ebp
movl $10000, %ecx # timeout
mov $COMCONSOLE + 5, %edx # line status reg
1:
decl %ecx
je 2f
inb %dx, %al
test $0x20, %al
testb $0x20, %al
jz 1b # TX buffer not empty
movb 0x8(%ebp), %al
movb 0x4(%esp), %al
sub $5, %edx # TX output reg
outb %al, %dx # send this one
2:
pop %ebp
ret
/*
@ -118,9 +115,6 @@ ENTRY(serial_putc)
*/
ENTRY(serial_getc)
push %ebp
mov %esp, %ebp
mov $COMCONSOLE + 5, %edx # line status reg
1:
inb %dx, %al
@ -131,12 +125,11 @@ ENTRY(serial_getc)
sub $5, %edx # RX buffer reg
inb %dx, %al # fetch (first) character
and $0x7F, %eax # remove any parity bits we get
cmp $0x7F, %eax # make DEL...
andb $0x7F, %al # remove any parity bits we get
cmpb $0x7F, %al # make DEL...
jne 2f
mov $0x08, %eax # look like BS
movb $0x08, %al # look like BS
2:
pop %ebp
ret
/*
@ -144,15 +137,10 @@ ENTRY(serial_getc)
* if there is a character pending, return true; otherwise return 0
*/
ENTRY(serial_ischar)
push %ebp
mov %esp, %ebp
xorl %eax, %eax
mov $COMCONSOLE + 5, %edx # line status reg
inb %dx, %al
andb $0x01, %al # RX char available?
pop %ebp
ret
/*
@ -160,9 +148,6 @@ ENTRY(serial_ischar)
* initialize the serial console port to 9600 Bd, 8 bpc
*/
ENTRY(init_serial)
push %ebp
mov %esp, %ebp
mov $COMCONSOLE + 3, %edx # line control reg
movb $0x80, %al
outb %al, %dx # enable DLAB
@ -183,19 +168,17 @@ ENTRY(init_serial)
outb %al, %dx # 8 bit, no parity, 1 stop bit
inc %edx # modem control reg
mov $3, %al
movb $3, %al
outb %al, %dx # enable DTR/RTS
/* now finally, flush the input buffer */
inc %edx # line status reg
1:
subl $5, %edx # rx buffer reg
inb %dx, %al # throw away (unconditionally the first time)
addl $5, %edx # line status reg
inb %dx, %al
testb $0x01, %al
jz 2f # no more characters buffered
sub $5, %edx # rx buffer reg
inb %dx, %al # throw away
add $5, %edx
jmp 1b
2:
pop %ebp
jne 1b # more
ret