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Showing results for tags 'command parsing'.
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A command parser/dispatcher example from my CO2 laser engraver codebase, using a struct array containing the commands and associated pointer to functions. A lot cleaner (and easier to maintain) than switch/case statements or if/else constructs... Functions get called with a pointer to the command tail for local parameter parsing. The struct array data are all placed in flash. typedef struct { char const *const command; bool (*const handler)(char *); const bool report; } command; bool query (char* params); bool start (char* params); bool moveXrel (char* params); bool moveYrel (char* params); bool moveZrel (char* params); bool XHome (char* params); bool YHome (char* params); bool ZHome (char* params); bool XYHome (char* params); bool zeroAllAxes (char* params); bool laser (char* params); bool setLaserPower (char* params); bool setImageDPI (char* params); bool setPulseDutyCycle (char* params); bool enableCoolant (char* params); bool enableAirAssist (char* params); bool setMode (char* params); bool getPosition (char* params); bool setPPI (char* params); bool setPulseWidth (char* params); bool enableExhaustFan (char* params); bool setEngravingSpeed (char* params); bool getStatus (char* params); bool setEchoMode (char* params); bool setAMode (char* params); bool setPWROffset (char* params); bool loadProfile (char* params); bool setXBcomp (char* params); void exeCommand (char *cmdline) { static const command commands[] = { "?", &query, true, "Power:", &setLaserPower, true, "DutyCycle:", &setPulseDutyCycle, true, "PulseWidth:", &setPulseWidth, true, "DPI:", &setImageDPI, true, "Start:", &start, true, "X:", &moveXrel, true, "Y:", &moveYrel, true, "Z:", &moveZrel, true, "HomeXY", &XYHome, true, "HomeX", &XHome, true, "HomeY", &YHome, true, "HomeZ", &ZHome, true, "ZeroAll", &zeroAllAxes, true, "Laser:", &laser, true, "Coolant:", &enableCoolant, true, "Air:", &enableAirAssist, true, "Mach3:", &setMode, true, "Pos", &getPosition, false, "PPI:", &setPPI, true, "Exhaust:", &enableExhaustFan, true, "Speed:", &setEngravingSpeed, true, "Status", &getStatus, false, "ASelect:", &setAMode, true, "PWROffset:", &setPWROffset, true, "LoadProfile:", &loadProfile, true, "XBComp:", &setXBcomp, true, "Echo:", &setEchoMode, false }; bool ok = false; uint32_t i = 0, numcmds = sizeof(commands) / sizeof(command), cmdlen; while(!ok && i < numcmds) { cmdlen = strlen(commands[i].command); if(!(ok = !strncmp(commands[i].command, cmdline, cmdlen))) i++; } if(ok) { ok = commands[i].handler(cmdline + cmdlen); if(commands[i].report) serialWriteLn(ok ? "OK" : "FAILED")); } else serialWriteLn("Bad command"); } For further reading see http://www.barrgroup.com/Embedded-Systems/How-To/C-Function-Pointers
