src/bin/dist/the_march.c~

   1 /*!@file
   2   \brief   engine entry
   3   \details initializes necessary subsystems before invoking the preloader,
   4            which loads initial game data, before finally invoking the
   5            main loop main_loop(void), which may be run in either blocking
   6            or non-blocking mode.
   7   \author  Mihrtec
   8   \date    2016
   9 ------------------------------------------------------------------------------*/
  10 #ifdef __EMSCRIPTEN__
  11 /* Web Environment */
  12 #define main em_main
  13 #include <SDL_ttf.h>
  14 #include <emscripten/emscripten.h>
  15 #else
  16 /* Traditional Environment */
  17 #ifdef __Win32
  18 #include <windows.h>
  19 #endif //__Win32
  20 #include <SDL2/SDL_ttf.h>
  21 #endif
  22 /* ENVIRONMENT-AGNOSTIC DEFINES */
  23 #include <SDL2/SDL.h>
  24 #include <SDL2/SDL_image.h>
  25 #include <stdint.h>
  26 #include <setjmp.h>
  27 #include <stdio.h>
  28 #define TRIGGERS quit_trigger
  29 #include <core/trigger.h>
  30 #include <core/engine.h>
  31
  32 /* exposed functions */
  33 void main_loop(void);
  34
  35 /* private functions */
  36 static int main_init(void);
  37
  38 /* unexposed externs */
  39 extern int         state_init(void);
  40 extern void        state_tick(uint32_t delta_ticks);
  41 extern const char* state_get_error(void);
  42 extern void        state_quit(void);
  43 extern void        state_handle_event(SDL_Event *event);
  44 #if 0
  45 extern int         io_init(void);
  46 extern const char* io_get_error(void);
  47 extern void        io_quit(void);
  48 #endif //TODO
  49
  50 /* main jump buffer */
  51 jmp_buf jmp_main;
  52
  53 /*@
  54   initializes subsystems and calls main_loop(void)
  55
  56   main sets a jump buffer for its primary switch, which may be jumped to
  57   at any time.  Jumping with a 0 return value is equivalent to calling
  58   setjmp directly, which initializes the system and begins the main loop.
  59   Jumping with any other value will process one of the directives associated
  60   with the exit codes in core.h
  61 */
  62 #ifdef __EMSCRIPTEN__
  63 #define main_loop()                                         \
  64   do {                                                      \
  65     emscripten_set_main_loop(main_loop,0,0);                \
  66     TRIGGER_SET(quit_trigger, emscripten_cancel_main_loop); \
  67     return 0;                                               \
  68   } while (0)
  69 #endif
  70
  71 int
  72 main (int argc, char** argv)
  73 { switch(setjmp(jmp_main))
  74     { case 0:
  75         if (main_init())
  76           return -1;
  77         main_loop();
  78       case EXIT_GRACEFUL:
  79         break;
  80       default:
  81       case EXIT_PANIC:
  82         //dump some debug info
  83         break;
  84     }
  85   TRIGGER(quit_trigger);
  86   return 0;
  87 }
  88
  89 #ifdef __EMSCRIPTEN__
  90 #undef main_loop
  91 #endif
  92
  93 /*@
  94   subsystem initializer
  95   Calling main_init() boots the system, and may be called multiple times to
  96   cause a system-wide reboot.
  97   @return 0 if successful, -1 SDL, -2 IMG, -3 TTF, -4 STATE.
  98   SDL and logging is available after this is called
  99 */
 100 #define INIT(_cond,_errorstring,_quit)                           \
 101   do {                                                           \
 102     if (_cond)                                                   \
 103       { fprintf(stderr, #_cond " failed: %s\n", _errorstring()); \
 104         return -1;                                               \
 105       }                                                          \
 106     TRIGGER_SET(quit_trigger, _quit);                            \
 107   } while (0)
 108
 109 #define SDL_FLAGS SDL_INIT_EVERYTHING & ~(SDL_INIT_TIMER | SDL_INIT_HAPTIC)
 110
 111 static int
 112 main_init()
 113 { static uint32_t bInitialized = 0;
 114   if (bInitialized++)
 115     { TRIGGER(quit_trigger);
 116       SDL_LogInfo(SDL_LOG_CATEGORY_APPLICATION, "Resetting [%d]\n",
 117                   bInitialized);
 118     }
 119
 120   INIT(SDL_Init(SDL_FLAGS) < 0, SDL_GetError, SDL_Quit);
 121   INIT(IMG_Init(IMG_INIT_PNG) != IMG_INIT_PNG, IMG_GetError, IMG_Quit);
 122   INIT(TTF_Init() == -1, TTF_GetError, TTF_Quit);
 123   INIT(state_init(), state_get_error, state_quit);
 124   INIT(fs_init(), fs_get_error, fs_quit);
 125
 126   SDL_Log("Initialization Complete.");
 127   return 0;
 128 }
 129
 130 /*@
 131   The main loop may be compiled in blocking or non-blocking mode, and
 132   synchronizes time in ticks (milliseconds) as established by SDL anchored
 133   on the state_tick() event.
 134 */
 135 void
 136 main_loop()
 137 { static uint32_t state_last_ticks = 0;
 138   SDL_Event event;
 139   uint32_t delta_ticks;
 140
 141 #ifndef NON_BLOCKING_LOOPS
 142 loop:
 143 #endif
 144   /* user/system inputs */
 145   while (SDL_PollEvent(&event))
 146       state_handle_event(&event);
 147
 148   /* change in time since last loop */
 149   delta_ticks = SDL_GetTicks() - state_last_ticks;
 150   /* handle breakpoints (long pause likely a breakpoint) */
 151   if (delta_ticks > 1000)
 152     { SDL_LogWarn(SDL_LOG_CATEGORY_SYSTEM, "Recovering from long pause.");
 153       delta_ticks = TARGET_DT;
 154     }
 155   /* tick the state manager and immediately save the time */
 156   state_tick(delta_ticks);
 157   state_last_ticks = SDL_GetTicks();
 158
 159   //TODO: render(screen)
 160   //TODO: SDL_Flip(screen)::sdl_geterror
 161
 162 #ifndef NON_BLOCKING_LOOPS
 163 #define DIV_UP(x,y) (((x) + ((y) / 2)) / (x))
 164   /* yield if we have a substantial portion of time leftover */
 165   delta_ticks += SDL_GetTicks() - state_last_ticks;
 166   if (delta_ticks < (TARGET_DT - DIV_UP(TARGET_DT, 10)))
 167     SDL_Delay(TARGET_DT - delta_ticks);
 168   goto loop;
 169 #endif
 170 }
 171