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simple
serial_rxtx.c
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/*
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* @file serial.c
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* Defines the serial receive and transmit routines.
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*
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* Copyright (c) 2013, Parallax Inc.
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* Written by Steve Denson
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*/
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#include <propeller.h>
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#include "serial.h"
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__attribute__((fcache)) static
int
_inbyte(
int
bitcycles,
int
cycle1,
int
rxmask,
int
value)
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{
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int
waitcycles;
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int
j = 8;
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cycle1 += cycle1 >> 2;
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/* wait for a start bit */
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waitpeq(0, rxmask);
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waitcycles = cycle1 + CNT;
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/* index initialized above */
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while
(j-- > 0) {
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/* C code is too big for fcache in xmm memory models.
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// waitcycles = waitcnt2(waitcycles, bitcycles); */
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__asm__
volatile
(
"waitcnt %[_waitcycles], %[_bitcycles]"
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: [_waitcycles]
"+r"
(waitcycles)
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: [_bitcycles]
"r"
(bitcycles));
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/* value = ( (0 != (INA & rxmask)) << 7) | (value >> 1); */
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__asm__
volatile
(
"shr %[_value],# 1\n\t"
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"test %[_mask],ina wz \n\t"
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"muxnz %[_value], #1<<7"
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: [_value]
"+r"
(value)
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: [_mask]
"r"
(rxmask));
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}
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return
value;
/* fcached 0x40 or 64 bytes */
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}
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int
serial_rxChar(
serial
*device)
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{
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Serial_t
*sp = (
Serial_t
*) device->
devst
;
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int
value = 0;
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/* set input */
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unsigned
int
rxmask = 1 << sp->
rx_pin
;
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if
(sp->
tx_pin
< SERIAL_MIN_PIN && sp->
tx_pin
> SERIAL_MAX_PIN)
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return
0;
/* don't receive on pins out of range */
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DIRA &= ~rxmask;
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value = _inbyte(sp->
ticks
, sp->
ticks
, rxmask, 0);
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/* wait for the line to go high (as it will when the stop bit arrives) */
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waitpeq(rxmask, rxmask);
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return
value & 0xff;
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}
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__attribute__((fcache)) static
void
_outbyte(
int
bitcycles,
int
txmask,
int
value)
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{
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int
j = 10;
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int
waitcycles;
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waitcycles = CNT + bitcycles;
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while
(j-- > 0) {
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/* C code is too big and not fast enough for all memory models.
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// waitcycles = waitcnt2(waitcycles, bitcycles); */
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__asm__
volatile
(
"waitcnt %[_waitcycles], %[_bitcycles]"
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: [_waitcycles]
"+r"
(waitcycles)
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: [_bitcycles]
"r"
(bitcycles));
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/* if (value & 1) OUTA |= txmask else OUTA &= ~txmask; value = value >> 1; */
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__asm__
volatile
(
"shr %[_value],#1 wc \n\t"
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"muxc outa, %[_mask]"
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: [_value]
"+r"
(value)
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: [_mask]
"r"
(txmask));
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}
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}
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int
serial_txChar(
serial
*device,
int
value)
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{
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Serial_t
*sp = (
Serial_t
*) device->
devst
;
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int
txmask = (1 << sp->
tx_pin
);
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if
(sp->
tx_pin
< SERIAL_MIN_PIN && sp->
tx_pin
> SERIAL_MAX_PIN)
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return
0;
/* don't transmit on pins out of range */
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DIRA |= txmask;
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_outbyte(sp->
ticks
, txmask, (value | 0x100) << 1);
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return
value;
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}
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/*
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+--------------------------------------------------------------------
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| TERMS OF USE: MIT License
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+--------------------------------------------------------------------
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Permission is hereby granted, free of charge, to any person obtaining
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a copy of this software and associated documentation files
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(the "Software"), to deal in the Software without restriction,
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including without limitation the rights to use, copy, modify, merge,
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publish, distribute, sublicense, and/or sell copies of the Software,
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and to permit persons to whom the Software is furnished to do so,
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subject to the following conditions:
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The above copyright notice and this permission notice shall be
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included in all copies or substantial portions of the Software.
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THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
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EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
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MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
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IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
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CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
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TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
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SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
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+--------------------------------------------------------------------
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*/
serial_info::tx_pin
int tx_pin
Definition:
serial.h:58
text_struct::devst
volatile void * devst
Definition:
simpletext.h:79
serial_info::rx_pin
int rx_pin
Definition:
serial.h:57
text_struct
Structure that contains data used by simple text device libraries.
Definition:
simpletext.h:70
serial_info::ticks
int ticks
Definition:
serial.h:61
serial_info
Defines serial interface structure of 9 contiguous int variables.
Definition:
serial.h:55
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