annotate target-utils/libbase/serio.S @ 854:74331b35b1da

ringtools/examples/ring.pwt: PWT equivalent of ring.buz
author Mychaela Falconia <falcon@freecalypso.org>
date Tue, 09 Nov 2021 16:39:52 +0000
parents da6df2c626cf
children
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1 #include "ns16550.h"
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3 @ this module implements the elementary serial I/O operations
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5 .comm uart_base,4,4
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7 .text
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8 .code 32
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9 .global serial_out
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10 serial_out:
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11 ldr r1, =uart_base
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12 ldr r2, [r1]
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13 1: ldrb r3, [r2, #0x11] @ Calypso UART non-std register SSR
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14 tst r3, #0x01 @ Tx FIFO full flag
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15 bne 1b
0
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16 strb r0, [r2, #NS16550_THR]
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17 bx lr
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19 .global serial_in_poll
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20 serial_in_poll:
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21 ldr r1, =uart_base
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22 ldr r2, [r1]
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23 ldrb r3, [r2, #NS16550_LSR]
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24 tst r3, #NS16550_LSR_DR
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25 ldrneb r0, [r2, #NS16550_RBR]
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26 mvneq r0, #0
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27 bx lr
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29 .global serial_flush
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30 serial_flush:
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31 ldr r1, =uart_base
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32 ldr r2, [r1]
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33 1: ldrb r3, [r2, #NS16550_LSR]
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34 tst r3, #NS16550_LSR_TEMP
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35 beq 1b
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36 bx lr