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1 | function [backoff_start, phy_tx_start, tx_done, fsm_state_out] = ... |
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2 | mac_tx_ctrl_cd_fsm(... |
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3 | reset, ... |
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4 | new_tx, ... |
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5 | require_backoff, ... |
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6 | backoff_done, ... |
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7 | idle_for_difs, ... |
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8 | phy_tx_done) |
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9 | |
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10 | persistent fsm_state, fsm_state=xl_state(0, {xlUnsigned, 3, 0}); |
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11 | |
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12 | fsm_state_out = fsm_state; |
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13 | |
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14 | %Inputs: |
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15 | % reset: synchronous reset, forces internal state variables back to default (IDLE state) |
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16 | % new_tx: Software request for new Tx cycle |
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17 | % backoff_done: Indication from MAC hw that backoff period is done |
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18 | % idle_for_difs: Indication from MAC hw that medium has been idle > DIFS/EIFS |
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19 | % phy_tx_done: Indication from PHY that last sample is transmitted |
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20 | |
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21 | %Outputs: |
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22 | % backoff_start: Indication to MAC hw to run idle->backoff process |
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23 | % phy_tx_start: Indication to PHY to start Tx |
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24 | % tx_done: Indication to MAC hw that this Tx cycle is complete |
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25 | % fsm_state_out: Value of internal state register (for debugging) |
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26 | |
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27 | ST_IDLE = 0; |
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28 | ST_START_BO = 1; |
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29 | ST_DEFER = 2; |
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30 | ST_DO_TX = 3; |
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31 | ST_DONE = 4; |
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32 | |
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33 | if(reset) |
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34 | backoff_start = 0; |
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35 | phy_tx_start = 0; |
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36 | tx_done = 0; |
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37 | fsm_state = ST_IDLE; |
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38 | |
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39 | else |
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40 | switch double(fsm_state) |
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41 | |
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42 | case ST_IDLE |
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43 | backoff_start = 0; |
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44 | phy_tx_start = 0; |
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45 | tx_done = 0; |
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46 | |
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47 | if(new_tx) |
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48 | if(idle_for_difs && ~require_backoff) |
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49 | %If medium is already idle and this Tx doesn't require a backoff, start Tx immediately |
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50 | fsm_state = ST_DO_TX; |
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51 | else |
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52 | %Busy medium, or backoff required; start backoff |
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53 | fsm_state = ST_START_BO; |
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54 | end |
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55 | else |
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56 | %No new Tx this cycle |
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57 | fsm_state = ST_IDLE; |
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58 | end |
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59 | |
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60 | case ST_START_BO |
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61 | %Start the backoff counter, then transition to DEFER |
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62 | backoff_start = 1; |
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63 | phy_tx_start = 0; |
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64 | tx_done = 0; |
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65 | |
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66 | fsm_state = ST_DEFER; |
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67 | |
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68 | case ST_DEFER |
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69 | backoff_start = 0; |
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70 | phy_tx_start = 0; |
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71 | tx_done = 0; |
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72 | |
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73 | %Stay here until backoff completes |
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74 | if(backoff_done) |
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75 | fsm_state = ST_DO_TX; |
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76 | else |
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77 | fsm_state = ST_DEFER; |
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78 | end |
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79 | |
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80 | case ST_DO_TX |
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81 | backoff_start = 0; |
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82 | phy_tx_start = 1; |
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83 | tx_done = 0; |
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84 | |
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85 | % Stay here until PHY Tx finishes |
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86 | if(phy_tx_done) |
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87 | fsm_state = ST_DONE; |
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88 | else |
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89 | fsm_state = ST_DO_TX; |
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90 | end |
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91 | |
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92 | case ST_DONE |
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93 | backoff_start = 0; |
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94 | phy_tx_start = 0; |
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95 | tx_done = 1; |
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96 | |
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97 | fsm_state = ST_IDLE; |
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98 | |
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99 | otherwise |
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100 | %This case should be impossible; mostly here to appease MATLAB |
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101 | backoff_start = 0; |
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102 | phy_tx_start = 0; |
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103 | tx_done = 0; |
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104 | fsm_state = ST_IDLE; |
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105 | |
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106 | end %end switch |
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107 | end %end else |
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108 | |
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109 | end %end function |
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