1/* 2 * Copyright (c) 1998 Robert Nordier 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms are freely 6 * permitted provided that the above copyright notice and this 7 * paragraph and the following disclaimer are duplicated in all 8 * such forms. 9 * 10 * This software is provided "AS IS" and without any express or 11 * implied warranties, including, without limitation, the implied 12 * warranties of merchantability and fitness for a particular 13 * purpose. 14 * 15 * $FreeBSD$ 16 */ 17 18 .set SIO_PRT,SIOPRT # Base port 19 .set SIO_FMT,SIOFMT # 8N1 20 21 .globl sio_init 22 .globl sio_flush 23 .globl sio_putc 24 .globl sio_getc 25 .globl sio_ischar 26 27/* int sio_init(int div) */ 28 29sio_init: pushl %eax 30 movw $SIO_PRT+0x3,%dx # Data format reg 31 movb $SIO_FMT|0x80,%al # Set format 32 outb %al,(%dx) # and DLAB 33 subb $0x3,%dl # Divisor latch reg 34 popl %eax 35 outw %ax,(%dx) # BPS 36 movw $SIO_PRT+0x3,%dx # Data format reg 37 movb $SIO_FMT,%al # Clear 38 outb %al,(%dx) # DLAB 39 incl %edx # Modem control reg 40 movb $0x3,%al # Set RTS, 41 outb %al,(%dx) # DTR 42 incl %edx # Line status reg 43 # Fallthrough 44 45/* int sio_flush(void) */ 46 47sio_flush: xorl %ecx,%ecx # Timeout 48 movb $0x80,%ch # counter 49sio_flush.1: call sio_ischar # Check for character 50 jz sio_flush.2 # Till none 51 loop sio_flush.1 # or counter is zero 52 movb $1, %al # Exhausted all tries 53sio_flush.2: ret # To caller 54 55/* void sio_putc(int c) */ 56 57sio_putc: pushl %eax 58 movw $SIO_PRT+0x5,%dx # Line status reg 59 xor %ecx,%ecx # Timeout 60 movb $0x40,%ch # counter 61sio_putc.1: inb (%dx),%al # Transmitter 62 testb $0x20,%al # buffer empty? 63 loopz sio_putc.1 # No 64 jz sio_putc.2 # If timeout 65 popl %eax # Get the character 66 subb $0x5,%dl # Transmitter hold reg 67 outb %al,(%dx) # Write character 68sio_putc.2: ret # To caller 69 70/* int sio_getc(void) */ 71 72sio_getc: call sio_ischar # Character available? 73 jz sio_getc # No 74sio_getc.1: subb $0x5,%dl # Receiver buffer reg 75 inb (%dx),%al # Read character 76 ret # To caller 77 78/* int sio_ischar(void) */ 79 80sio_ischar: movw $SIO_PRT+0x5,%dx # Line status register 81 xorl %eax,%eax # Zero 82 inb (%dx),%al # Received data 83 andb $0x1,%al # ready? 84 ret # To caller 85