author Ryan C. Gordon <>
Tue, 20 Aug 2013 14:17:48 -0400
changeset 7664 6995a81e065a
parent 7191 75360622e65f
child 7736 84d89d60908f
permissions -rw-r--r--
Added SDL_assert_always (never disabled).

  Simple DirectMedia Layer
  Copyright (C) 1997-2013 Sam Lantinga <>

  This software is provided 'as-is', without any express or implied
  warranty.  In no event will the authors be held liable for any damages
  arising from the use of this software.

  Permission is granted to anyone to use this software for any purpose,
  including commercial applications, and to alter it and redistribute it
  freely, subject to the following restrictions:

  1. The origin of this software must not be misrepresented; you must not
     claim that you wrote the original software. If you use this software
     in a product, an acknowledgment in the product documentation would be
     appreciated but is not required.
  2. Altered source versions must be plainly marked as such, and must not be
     misrepresented as being the original software.
  3. This notice may not be removed or altered from any source distribution.

#ifndef _SDL_assert_h
#define _SDL_assert_h

#include "SDL_config.h"

#include "begin_code.h"
/* Set up for C function definitions, even when using C++ */
#ifdef __cplusplus
extern "C" {

#elif defined(_DEBUG) || defined(DEBUG) || \
      (defined(__GNUC__) && !defined(__OPTIMIZE__))
#endif /* SDL_ASSERT_LEVEL */

These are macros and not first class functions so that the debugger breaks
on the assertion line and not in some random guts of SDL, and so each
assert can have unique static variables associated with it.

#if defined(_MSC_VER)
/* Don't include intrin.h here because it contains C++ code */
    extern void __cdecl __debugbreak(void);
    #define SDL_TriggerBreakpoint() __debugbreak()
#elif (defined(__GNUC__) && (defined(__i386__) || defined(__x86_64__)))
    #define SDL_TriggerBreakpoint() __asm__ __volatile__ ( "int $3\n\t" )
#elif defined(HAVE_SIGNAL_H)
    #include <signal.h>
    #define SDL_TriggerBreakpoint() raise(SIGTRAP)
    /* How do we trigger breakpoints on this platform? */
    #define SDL_TriggerBreakpoint()

#if defined(__STDC_VERSION__) && (__STDC_VERSION__ >= 199901L) /* C99 supports __func__ as a standard. */
#   define SDL_FUNCTION __func__
#elif ((__GNUC__ >= 2) || defined(_MSC_VER))
#   define SDL_FUNCTION "???"
#define SDL_FILE    __FILE__
#define SDL_LINE    __LINE__

sizeof (x) makes the compiler still parse the expression even without
assertions enabled, so the code is always checked at compile time, but
doesn't actually generate code for it, so there are no side effects or
expensive checks at run time, just the constant size of what x WOULD be,
which presumably gets optimized out as unused.
This also solves the problem of...

    int somevalue = blah();
    SDL_assert(somevalue == 1);

...which would cause compiles to complain that somevalue is unused if we
disable assertions.

#define SDL_disabled_assert(condition) \
    do { (void) sizeof ((condition)); } while (0)

typedef enum
    SDL_ASSERTION_RETRY,  /**< Retry the assert immediately. */
    SDL_ASSERTION_BREAK,  /**< Make the debugger trigger a breakpoint. */
    SDL_ASSERTION_ABORT,  /**< Terminate the program. */
    SDL_ASSERTION_IGNORE,  /**< Ignore the assert. */
    SDL_ASSERTION_ALWAYS_IGNORE  /**< Ignore the assert from now on. */
} SDL_assert_state;

typedef struct SDL_assert_data
    int always_ignore;
    unsigned int trigger_count;
    const char *condition;
    const char *filename;
    int linenum;
    const char *function;
    const struct SDL_assert_data *next;
} SDL_assert_data;


/* Never call this directly. Use the SDL_assert* macros. */
extern DECLSPEC SDL_assert_state SDLCALL SDL_ReportAssertion(SDL_assert_data *,
                                                             const char *,
                                                             const char *, int);

/* the do {} while(0) avoids dangling else problems:
    if (x) SDL_assert(y); else blah();
       ... without the do/while, the "else" could attach to this macro's "if".
   We try to handle just the minimum we need here in a macro...the loop,
   the static vars, and break points. The heavy lifting is handled in
   SDL_ReportAssertion(), in SDL_assert.c.
#define SDL_enabled_assert(condition) \
    do { \
        while ( !(condition) ) { \
            static struct SDL_assert_data assert_data = { \
                0, 0, #condition, 0, 0, 0, 0 \
            }; \
            const SDL_assert_state state = SDL_ReportAssertion(&assert_data, \
                                                               SDL_FUNCTION, \
                                                               SDL_FILE, \
                                                               SDL_LINE); \
            if (state == SDL_ASSERTION_RETRY) { \
                continue; /* go again. */ \
            } else if (state == SDL_ASSERTION_BREAK) { \
                SDL_TriggerBreakpoint(); \
            } \
            break; /* not retrying. */ \
        } \
    } while (0)

#endif  /* enabled assertions support code */

/* Enable various levels of assertions. */
#if SDL_ASSERT_LEVEL == 0   /* assertions disabled */
#   define SDL_assert(condition) SDL_disabled_assert(condition)
#   define SDL_assert_release(condition) SDL_disabled_assert(condition)
#   define SDL_assert_paranoid(condition) SDL_disabled_assert(condition)
#elif SDL_ASSERT_LEVEL == 1  /* release settings. */
#   define SDL_assert(condition) SDL_disabled_assert(condition)
#   define SDL_assert_release(condition) SDL_enabled_assert(condition)
#   define SDL_assert_paranoid(condition) SDL_disabled_assert(condition)
#elif SDL_ASSERT_LEVEL == 2  /* normal settings. */
#   define SDL_assert(condition) SDL_enabled_assert(condition)
#   define SDL_assert_release(condition) SDL_enabled_assert(condition)
#   define SDL_assert_paranoid(condition) SDL_disabled_assert(condition)
#elif SDL_ASSERT_LEVEL == 3  /* paranoid settings. */
#   define SDL_assert(condition) SDL_enabled_assert(condition)
#   define SDL_assert_release(condition) SDL_enabled_assert(condition)
#   define SDL_assert_paranoid(condition) SDL_enabled_assert(condition)
#   error Unknown assertion level.

/* this assertion is never disabled at any level. */
#define SDL_assert_always(condition) SDL_enabled_assert(condition)

typedef SDL_assert_state (SDLCALL *SDL_AssertionHandler)(
                                 const SDL_assert_data* data, void* userdata);

 *  \brief Set an application-defined assertion handler.
 *  This allows an app to show its own assertion UI and/or force the
 *  response to an assertion failure. If the app doesn't provide this, SDL
 *  will try to do the right thing, popping up a system-specific GUI dialog,
 *  and probably minimizing any fullscreen windows.
 *  This callback may fire from any thread, but it runs wrapped in a mutex, so
 *  it will only fire from one thread at a time.
 *  Setting the callback to NULL restores SDL's original internal handler.
 *  This callback is NOT reset to SDL's internal handler upon SDL_Quit()!
 *  \return SDL_assert_state value of how to handle the assertion failure.
 *  \param handler Callback function, called when an assertion fails.
 *  \param userdata A pointer passed to the callback as-is.
extern DECLSPEC void SDLCALL SDL_SetAssertionHandler(
                                            SDL_AssertionHandler handler,
                                            void *userdata);

 *  \brief Get a list of all assertion failures.
 *  Get all assertions triggered since last call to SDL_ResetAssertionReport(),
 *  or the start of the program.
 *  The proper way to examine this data looks something like this:
 *  <code>
 *  const SDL_assert_data *item = SDL_GetAssertionReport();
 *  while (item) {
 *      printf("'%s', %s (%s:%d), triggered %u times, always ignore: %s.\n",
 *             item->condition, item->function, item->filename,
 *             item->linenum, item->trigger_count,
 *             item->always_ignore ? "yes" : "no");
 *      item = item->next;
 *  }
 *  </code>
 *  \return List of all assertions.
 *  \sa SDL_ResetAssertionReport
extern DECLSPEC const SDL_assert_data * SDLCALL SDL_GetAssertionReport(void);

 *  \brief Reset the list of all assertion failures.
 *  Reset list of all assertions triggered.
 *  \sa SDL_GetAssertionReport
extern DECLSPEC void SDLCALL SDL_ResetAssertionReport(void);

/* Ends C function definitions when using C++ */
#ifdef __cplusplus
#include "close_code.h"

#endif /* _SDL_assert_h */

/* vi: set ts=4 sw=4 expandtab: */