--- src/sys/boot/i386/boot2/Attic/sio.s	2003/11/10 06:08:35	1.3
+++ src/sys/boot/i386/boot2/Attic/sio.s	2004/06/26 23:41:06	1.4
@@ -29,18 +29,20 @@
 # void sio_init(void)
 
 sio_init:	movw $SIO_PRT+0x3,%dx		# Data format reg
-		movb $SIO_FMT|0x80,%al		# Set format
-		outb %al,(%dx)			#  and DLAB
-		pushl %edx			# Save
-		subb $0x3,%dl			# Divisor latch reg
-		movw $SIO_DIV,%ax		# Set
-		outw %ax,(%dx)			#  BPS
-		popl %edx			# Restore
-		movb $SIO_FMT,%al		# Clear
-		outb %al,(%dx)			#  DLAB
-		incl %edx			# Modem control reg
-		movb $0x3,%al			# Set RTS,
-		outb %al,(%dx)			#  DTR
+		movb $SIO_FMT|0x80,%al		# Set format and DLAB
+		outb %al,(%dx)			# BASE+3
+		subb $0x3,%dl
+		movw $SIO_DIV,%ax		# divisor
+		outw %ax,(%dx)			# BASE+0 (divisor w/ DLAB set)
+		movw $SIO_PRT+0x2,%dx
+		movb $0x01,%al			# Enable FIFO
+		outb %al,(%dx)			# BASE+2
+		incl %edx
+		movb $SIO_FMT,%al		# Clear DLAB
+		outb %al,(%dx)			# BASE+3
+		incl %edx
+		movb $0x3,%al			# RTS+DTR
+		outb %al,(%dx)			# BASE+4
 		incl %edx			# Line status reg
 
 # void sio_flush(void)
@@ -48,21 +50,21 @@ sio_init:	movw $SIO_PRT+0x3,%dx		# Data
 sio_flush.0:	call sio_getc.1 		# Get character
 sio_flush:	call sio_ischar 		# Check for character
 		jnz sio_flush.0 		# Till none
-		ret				# To caller
+		ret
 
 # void sio_putc(int c)
 
 sio_putc:	movw $SIO_PRT+0x5,%dx		# Line status reg
-		xor %ecx,%ecx			# Timeout
-		movb $0x40,%ch			#  counter
-sio_putc.1:	inb (%dx),%al			# Transmitter
-		testb $0x20,%al 		#  buffer empty?
+		movb $0x40,%ch			# Timeout counter.  Allow %cl
+						# to contain garbage.
+sio_putc.1:	inb (%dx),%al			# Transmitter buffer empty?
+		testb $0x20,%al
 		loopz sio_putc.1		# No
 		jz sio_putc.2			# If timeout
 		movb 0x4(%esp,1),%al		# Get character
 		subb $0x5,%dl			# Transmitter hold reg
 		outb %al,(%dx)			# Write character
-sio_putc.2:	ret $0x4			# To caller
+sio_putc.2:	ret $0x4
 
 # int sio_getc(void)
 
@@ -70,12 +72,12 @@ sio_getc:	call sio_ischar 		# Character
 		jz sio_getc			# No
 sio_getc.1:	subb $0x5,%dl			# Receiver buffer reg
 		inb (%dx),%al			# Read character
-		ret				# To caller
+		ret
 
 # int sio_ischar(void)
 
 sio_ischar:	movw $SIO_PRT+0x5,%dx		# Line status register
 		xorl %eax,%eax			# Zero
-		inb (%dx),%al			# Received data
-		andb $0x1,%al			#  ready?
-		ret				# To caller
+		inb (%dx),%al			# Received data ready?
+		andb $0x1,%al
+		ret