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/*
* Copyright (c) 2025 Ian Marco Moffett and the Osmora Team.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of Hyra nor the names of its
* contributors may be used to endorse or promote products derived from
* this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/
.set UART_COM1, 0x3F8
.macro bus_outb port, val
mov $\port, %rdi
mov $\val, %rsi
call pio_outb
.endm
.text
.globl uart_init
uart_init:
/*
* void uart_init(void);
*/
push %r12
push %r13
push %r14
push %r15
push %rbx
push %rbp
bus_outb UART_COM1+1, 0x00 /* Disable interrupts */
bus_outb UART_COM1+3, 1<<7 /* Set DLAB */
bus_outb UART_COM1+0, 0x02 /* 57600 buad */
bus_outb UART_COM1+1, 0x00 /* High bits */
bus_outb UART_COM1+3, 0x03 /* Line control [data+stop,no parity] */
bus_outb UART_COM1+2, 0x00 /* Set FIFO, 14-byte threshold */
bus_outb UART_COM1+4, 0x0B /* DTR+RTS */
pop %rbp
pop %rbx
pop %r15
pop %r14
pop %r13
pop %r12
retq
uart_write:
/*
* void uart_write(const char *s, size_t len);
*/
push %r12
push %r13
push %r14
push %r15
push %rbx
push %rbp
mov %rsi, %rcx
mov %rdi, %rsi
.strloop:
lodsb
mov $UART_COM1, %dx
out %al, %dx
loop .strloop
pop %rbp
pop %rbx
pop %r15
pop %r14
pop %r13
pop %r12
.done:
retq
/* vim: ft=gas :
*/
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