50 lines
2.4 KiB
ArmAsm
50 lines
2.4 KiB
ArmAsm
/*-*- mode:unix-assembly; indent-tabs-mode:t; tab-width:8; coding:utf-8 -*-│
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│vi: set et ft=asm ts=8 tw=8 fenc=utf-8 :vi│
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╞══════════════════════════════════════════════════════════════════════════════╡
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│ Copyright 2020 Justine Alexandra Roberts Tunney │
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│ │
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│ This program is free software; you can redistribute it and/or modify │
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│ it under the terms of the GNU General Public License as published by │
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│ the Free Software Foundation; version 2 of the License. │
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│ │
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│ This program is distributed in the hope that it will be useful, but │
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│ WITHOUT ANY WARRANTY; without even the implied warranty of │
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│ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU │
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│ General Public License for more details. │
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│ │
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│ You should have received a copy of the GNU General Public License │
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│ along with this program; if not, write to the Free Software │
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│ Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA │
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│ 02110-1301 USA │
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╚─────────────────────────────────────────────────────────────────────────────*/
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#include "ape/macros.h"
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#include "libc/nexgen32e/uart.h"
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#include "libc/notice.inc"
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.real
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.code16 # ∩ .code32 ∩ .code64
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/ Receives byte over serial line.
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/
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/ This is both blocking and asynchronous.
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/
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/ @param di serial port
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/ @return ax character received
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/ @mode long,legacy,real
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/ @see ttytxr
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sgetc: push %bp
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mov %sp,%bp
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mov %di,%dx
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add $UART_LSR,%dx
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mov $UART_TTYDA,%ah
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1: in %dx,%al
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and %ah,%al
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rep nop # todo(jart): interrupts are better
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jz 1b
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mov %di,%dx
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xor %ax,%ax
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in %dx,%al
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pop %bp
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ret
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.endfn sgetc,globl
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.source __FILE__
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