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272
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1
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2 = processes / threads =
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3
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4 Processes are completely seperated and fully pre-emptive.
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5 This means a process can be unscheduled at any moment.
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6
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7 Threads are co-operative. This means they yield control
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8 voluntary. This means that mutexes and locks are not required.
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9 This is done with the built-in language feature called tasks.
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10
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11 If some heavy duty task must be performed, either way spawn
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12 a new process, or yield frequently from this hard labour.
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13
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14 = tasks =
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15
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16 Consider the following::
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17
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18 --
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19 function int insanemath(int a)
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20 {
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21 while (a > 0)
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22 {
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23 a = a -1;
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24 resume agent1;
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25 }
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26 return a - 1;
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27 }
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28
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29 task agent1()
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30 {
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31 start agent2;
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32 }
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33
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34 task agent2()
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35 {
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36 insanemath(55);
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37 insanemath(44);
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38 }
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39
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40 task main()
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41 {
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42 start agent1;
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43 join agent1;
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44 }
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45 --
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46
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47 Say to tasks are running in concurrent / parallel.
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48
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49
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50
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51 Stack layout for tasks.
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52 ||
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53 ||
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54 \/
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55 +---------+
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56 | return address
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57 | locals
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58 |
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59 +------
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60 | return address
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61 | locals
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62 |
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63 +---
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64
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65 Assembly code for the functions above:
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66
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67 .code
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68 insanemath:
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69 L1:
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70 load r0, sp - 4
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71 cmp r0, 0
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72 jl L2
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73 dec r0
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74 store r0, sp - 4
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75 jmp L1
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76 L2:
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77 ret
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78
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79 agent1:
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80 hlt?
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81
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82 agent2:
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83 hlt?
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84
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85 main:
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86 jmp agent1
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87
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88 .data
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89 agent1_task:
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90 dd 0
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91 agent2_task:
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92 dd 0
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93
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