1 | |
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2 | -- This is an example of how to attach and handle interrupts in Ada 95. |
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3 | -- Interrupt handling is done as follows: |
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4 | -- |
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5 | -- 1. A protected procedure is attached to the interrupt |
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6 | -- 2. When activated, the procedure enables a conditional entry |
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7 | -- 3. A task waiting on the entry will carry out the work. |
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8 | -- |
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9 | -- In this way, we spend minimum amount of time in the protected |
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10 | -- procedure. Many other schemes are of course possible... |
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11 | -- |
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12 | -- Written by Tullio Vardanega and Jiri Gaisler |
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13 | -- European Space Agency, 1999. |
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14 | -- |
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15 | |
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16 | |
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17 | with Ada.Interrupts; |
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18 | with System; |
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19 | with Ada.Text_IO; |
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20 | |
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21 | package body Interrupt_pkg is |
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22 | |
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23 | type T_SEM is (HIGH, LOW); |
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24 | |
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25 | Protected_Priority : constant System.Interrupt_Priority := |
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26 | System.Interrupt_Priority'First; |
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27 | |
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28 | -- Protected object, including interrupt handler (Signal) and conditional entry. |
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29 | |
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30 | protected Handler is |
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31 | procedure Signal; |
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32 | entry Wait; |
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33 | pragma Attach_Handler (Signal, 17); -- Signal 17 equals irq 1 on ERC32 |
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34 | pragma Priority (Protected_Priority); |
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35 | private |
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36 | BARRIER : T_SEM := HIGH; |
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37 | end Handler; |
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38 | |
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39 | protected body Handler is |
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40 | procedure Signal is |
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41 | begin |
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42 | BARRIER := LOW; |
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43 | end Signal; |
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44 | entry Wait when (BARRIER = LOW) is |
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45 | begin |
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46 | BARRIER := HIGH; |
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47 | end Wait; |
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48 | end Handler; |
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49 | |
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50 | -- Sporadic task, waiting on entry (Wait) for the interrupt. |
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51 | |
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52 | task sporadic is |
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53 | pragma Priority (8); |
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54 | end sporadic; |
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55 | |
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56 | task body sporadic is |
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57 | Message : constant STRING := |
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58 | "sporadic activated"; |
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59 | begin |
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60 | loop |
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61 | Handler.Wait; |
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62 | Ada.Text_IO.Put_line (Message); |
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63 | end loop; |
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64 | end sporadic; |
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65 | |
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66 | -- Test program, generating interrupt 1 on ERC32 |
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67 | |
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68 | procedure itest is |
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69 | procedure irqforce(irq : integer); |
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70 | pragma Import (C, irqforce, "irqforce"); |
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71 | begin |
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72 | for i in 1..10 loop |
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73 | irqforce(1); |
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74 | delay(0.05); |
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75 | end loop; |
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76 | |
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77 | -- Have to kill sporadic to exit since it is has an infinite loop |
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78 | abort sporadic; |
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79 | end; |
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80 | |
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81 | begin |
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82 | |
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83 | itest; |
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84 | |
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85 | end Interrupt_pkg; |
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86 | |
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87 | |
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