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 16 .set SIO_PRT,SIOPRT # Base port 17 .set SIO_FMT,SIOFMT # 8N1 18 19 .globl sio_init 20 .globl sio_flush 21 .globl sio_putc 22 .globl sio_getc 23 .globl sio_ischar 24 25/* int sio_init(int div) */ 26 27sio_init: pushl %eax 28 movw $SIO_PRT+0x3,%dx # Data format reg 29 movb $SIO_FMT|0x80,%al # Set format 30 outb %al,(%dx) # and DLAB 31 subb $0x3,%dl # Divisor latch reg 32 popl %eax 33 outw %ax,(%dx) # BPS 34 movw $SIO_PRT+0x3,%dx # Data format reg 35 movb $SIO_FMT,%al # Clear 36 outb %al,(%dx) # DLAB 37 incl %edx # Modem control reg 38 movb $0x3,%al # Set RTS, 39 outb %al,(%dx) # DTR 40 incl %edx # Line status reg 41 # Fallthrough 42 43/* int sio_flush(void) */ 44 45sio_flush: xorl %ecx,%ecx # Timeout 46 movb $0x80,%ch # counter 47sio_flush.1: call sio_ischar # Check for character 48 jz sio_flush.2 # Till none 49 loop sio_flush.1 # or counter is zero 50 movb $1, %al # Exhausted all tries 51sio_flush.2: ret # To caller 52 53/* void sio_putc(int c) */ 54 55sio_putc: pushl %eax 56 movw $SIO_PRT+0x5,%dx # Line status reg 57 xor %ecx,%ecx # Timeout 58 movb $0x40,%ch # counter 59sio_putc.1: inb (%dx),%al # Transmitter 60 testb $0x20,%al # buffer empty? 61 loopz sio_putc.1 # No 62 jz sio_putc.2 # If timeout 63 popl %eax # Get the character 64 subb $0x5,%dl # Transmitter hold reg 65 outb %al,(%dx) # Write character 66sio_putc.2: ret # To caller 67 68/* int sio_getc(void) */ 69 70sio_getc: call sio_ischar # Character available? 71 jz sio_getc # No 72sio_getc.1: subb $0x5,%dl # Receiver buffer reg 73 inb (%dx),%al # Read character 74 ret # To caller 75 76/* int sio_ischar(void) */ 77 78sio_ischar: movw $SIO_PRT+0x5,%dx # Line status register 79 xorl %eax,%eax # Zero 80 inb (%dx),%al # Received data 81 andb $0x1,%al # ready? 82 ret # To caller 83