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109 lines
2.3 KiB
109 lines
2.3 KiB
/** @file race1.c
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@author M. P. Hayes, UCECE
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@date 7 October 2013
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@brief Test program for IR UART communications showing possible
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race condition.
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@note Not tested yet...
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*/
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#include "system.h"
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#include "navswitch.h"
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#include "tinygl.h"
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#include "task.h"
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#include "ir_uart.h"
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#include "../fonts/font5x7_1.h"
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#define DISPLAY_TASK_RATE 200
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#define IR_UART_TX_TASK_RATE 20
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#define IR_UART_RX_TASK_RATE 20
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#define NAVSWITCH_TASK_RATE 20
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typedef enum state {STATE_UNKNOWN, STATE_FIRST, STATE_SECOND} state_t;
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static state_t this_state = STATE_UNKNOWN;
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static state_t other_state = STATE_UNKNOWN;
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static void display_task (__unused__ void *data)
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{
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tinygl_update ();
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}
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static void ir_uart_tx_task (__unused__ void *data)
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{
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/* Send our state. */
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ir_uart_putc ('A' + this_state);
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}
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static void ir_uart_rx_task (__unused__ void *data)
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{
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state_t newstate;
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if (!ir_uart_read_ready_p ())
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return;
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newstate = ir_uart_getc () - 'A';
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/* Check for corrupted message. */
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if (newstate > STATE_SECOND)
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return;
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/* See if other devices state has changed. */
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if (other_state != newstate)
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{
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other_state = newstate;
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if (this_state == STATE_UNKNOWN && other_state == STATE_FIRST)
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{
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this_state = STATE_SECOND;
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tinygl_text ("2");
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}
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else
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{
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/* So what should we do if there is a disagreement?
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What if both devices think they were first? */
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}
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}
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}
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static void navswitch_task (__unused__ void *data)
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{
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navswitch_update ();
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if (navswitch_push_event_p (NAVSWITCH_PUSH))
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{
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if (this_state == STATE_UNKNOWN)
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{
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this_state = STATE_FIRST;
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tinygl_text ("1");
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}
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}
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}
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int main (void)
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{
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task_t tasks[] =
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{
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{.func = display_task, .period = TASK_RATE / DISPLAY_TASK_RATE},
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{.func = ir_uart_rx_task, .period = TASK_RATE / IR_UART_RX_TASK_RATE},
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{.func = ir_uart_tx_task, .period = TASK_RATE / IR_UART_TX_TASK_RATE},
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{.func = navswitch_task, .period = TASK_RATE / NAVSWITCH_TASK_RATE},
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};
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system_init ();
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ir_uart_init ();
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tinygl_init (DISPLAY_TASK_RATE);
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tinygl_font_set (&font5x7_1);
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tinygl_text ("*");
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task_schedule (tasks, 4);
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return 0;
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}
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