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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 I8254_COMMAND, 0x43
.set I8254_CHANNEL0, 0x40
.text
.globl i8254_set_count
i8254_set_count:
/*
* RDI: Count
*/
push %r12
push %r13
push %r14
push %r15
push %rbx
push %rbp
mov %rdi, %rax /* Count -> RAX */
mov $0x34, %al /* Latch lo/hi bytes */
out %al, $I8254_COMMAND /* Send the command */
out %al, $I8254_CHANNEL0 /* Write low byte */
shr $8, %ah /* Shift down, get high byte */
out %al, $I8254_CHANNEL0 /* Write high byte */
pop %rbp
pop %rbx
pop %r15
pop %r14
pop %r13
pop %r12
retq
.globl i8254_get_count
i8254_get_count:
push %r12
push %r13
push %r14
push %r15
push %rbx
push %rbp
mov $0x00, %al /* Get the current counter */
out %al, $I8254_COMMAND /* Send the command */
xor %rdx, %rdx /* Make sure RDX is zeroed */
in $I8254_CHANNEL0, %al /* Read low byte */
mov %al, %dl /* Set low byte */
in $I8254_CHANNEL0, %al /* Read high byte */
shl $8, %dh /* Shift to make room */
or %al, %dl /* Merge high and low */
mov %rdx, %rax /* Return what we got */
pop %rbp
pop %rbx
pop %r15
pop %r14
pop %r13
pop %r12
retq
/* vim: ft=gas :
*/
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