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;Copyright 2019 Benji Dial
;Permission to use, copy, modify, and/or distribute this
;software for any purpose with or without fee is hereby
;granted, provided that the above copyright notice and this
;permission notice appear in all copies.
;THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS
;ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL
;IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO
;EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT,
;INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER
;RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
;ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION,
;ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE
;OF THIS SOFTWARE.
global send_byte
global read_byte
send_byte:;void send_byte(uint8_t value, uint8_t port)
push ebp
mov ebp, esp
mov cl, byte [ebp + 8] ;value
xor edx, edx
mov dl, byte [ebp + 12];port
test dl, 0xfc
jnz .leave
xchg ebx, edx
shl bl, 1
mov ax, word [ebx + com_ports]
mov ebx, edx
mov dx, ax
or dx, 5
.check_ready:
in al, dx
test al, 0x20
jz .check_ready
and dx, 0xfff8
mov al, cl
out dx, al
.leave:
leave
ret
read_byte:;uint8_t read_byte(uint8_t port)
push ebp
mov ebp, esp
xor eax, eax
xor edx, edx
mov dl, byte [ebp + 8];port
test dl, 0xfc
jnz .leave
xchg ebx, edx
shl bl, 1
mov cx, word [ebx + com_ports]
mov ebx, edx
mov dx, cx
or dx, 5
.check_ready:
in al, dx
test al, 0x01
jz .check_ready
and dx, 0xfff8
in al, dx
.leave:
leave
ret
section .rodata
com_ports dw 0x03f8, 0x02f8, 0x03e8, 0x02e8
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