63 lines
1.3 KiB
ArmAsm
63 lines
1.3 KiB
ArmAsm
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/* https://github.com/cirosantilli/x86-bare-metal-examples#serial-uart */
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#include "common.h"
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#define PORT 0x3f8
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BEGIN
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/* Initialize the serial. */
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/* Disable all interrupts */
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mov 0x00, %al
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mov $(PORT + 1), %dx
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out %al, %dx
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/* Enable DLAB (set baud rate divisor) */
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mov 0x80, %al
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mov $(PORT + 3), %dx
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out %al, %dx
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/* Set divisor to 3 (lo byte) 38400 baud */
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mov 0x03, %al
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mov $(PORT + 0), %dx
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out %al, %dx
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/* Set divisor to 3 (hi byte) 38400 baud */
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mov 0x00, %al
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mov $(PORT + 1), %dx
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out %al, %dx
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/* 8 bits, no parity, one stop bit */
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mov 0x03, %al
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mov $(PORT + 3), %dx
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out %al, %dx
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/* Enable FIFO, clear them, with 14-byte threshold */
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mov 0xC7, %al
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mov $(PORT + 2), %dx
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out %al, %dx
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/* IRQs enabled, RTS/DSR set */
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mov 0x0B, %al
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mov $(PORT + 4), %dx
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out %al, %dx
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mov $(PORT + 0), %dx
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mov $msg, %si
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.Lloop:
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/* is_transmit_empty */
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mov $(PORT + 5), %dx
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inb %dx
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and $0x20, %al
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jz .Lloop
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/* Read value and check if NUL. */
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lodsb
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mov $0x01, %ah
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or %al, %al
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jz .Lhalt
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/* Send value to serial. */
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out %al, %dx
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/* Stop in infinite loop. */
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jmp .Lloop
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.Lhalt:
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hlt
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jmp .Lhalt
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msg:
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.asciz "hello world\n"
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