C语言状态机的两种表示方式

#include <stdlib.h> #include <stdio.h> #define transition_num 11 #define state_num 6 typedef void (*action_foo)() ; enum state { s_stop='s', s_play='p', s_forward='f', s_backward='b', s_pause='_', s_record='r' }; enum message { play, stop, forward, backward, record, pause }; /* action starts */ void do_stop() {printf ("I am in state stop and should doing something here.\n");} void do_play() {printf ("I am in state play and should doing something here.\n");} void do_forward() {printf ("I am in state forward and should doing something here.\n");} void do_backward() {printf ("I am in state backward and should doing something here.\n");} void do_pause() {printf ("I am in state pause and should doing something here.\n");} void do_record() {printf ("I am in state record and should doing something here.\n");} struct state_action { enum state m_state; action_foo foo; }; struct state_action state_action_map[state_num] = { {s_stop, do_stop}, {s_play, do_play}, {s_forward, do_forward}, {s_backward, do_backward}, {s_pause, do_pause}, {s_record, do_record}}; action_foo ACTION_NOT_FOUND = NULL; action_foo lookup_action(enum state s, struct state_action* a) { action_foo ret = ACTION_NOT_FOUND; int i=0; for (i=0;i<state_num;++i) { if(s == a[i].m_state) { ret = a[i].foo; } } return ret; } /* action ends. */ /* transition starts*/ struct transition { enum state current; enum message m; enum state next; }; struct transition fsm[transition_num] = { /* current_state, message/event, next_state*/ {s_play, stop, s_stop}, {s_play, pause, s_pause}, {s_pause, pause, s_play}, {s_pause, stop, s_stop}, {s_stop, forward, s_forward}, {s_stop, play, s_play}, {s_stop, backward, s_backward}, {s_stop, record, s_record}, {s_forward, stop, s_stop}, {s_backward, stop, s_stop}, {s_record, stop, s_stop} }; int const ERR = -1; int lookup_transition (enum state s, enum message m, struct transition * t) { int ret=ERR; int i; for(i=0;i<transition_num;++i) { if(t[i].current == s && t[i].m == m) { ret = i; } } return ret; } /* transition ends*/ void state_change(enum message m) { static state = s_stop; enum state next; int index = 0; index = lookup_transition(state, m, fsm); if(index!=ERR) { state = fsm[index].next; lookup_action(state, state_action_map)(); } return; } int main(int argc, char *argv[]) { char c=0x00; while(1) { c = getchar(); printf ("%c input.\n", c); switch(c) { case ' ': state_change(pause); break; case 'p': state_change(play); break; case 'r': state_change(record); break; case 's': state_change(stop); break; case 'f': state_change(forward); break; case 'b': state_change(backward); break; case 'q': return EXIT_SUCCESS; } } return EXIT_SUCCESS; }