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view docs/html/sdljoybuttonevent.html @ 1544:ab1e4c41ab71
Fixed bug #33
Mike Frysinger wrote:
> with libsdl-1.2.9, some games (like bomberclone) started
> segfaulting in Gentoo
[...snip...]
> the last change in the last hunk:
[...snip...]
> if i change the statement to read:
> (table[which].blit_features & GetBlitFeatures()) == GetBlitFeatures()
> bomberclone no longer segfaults on my box
Alex Volkov wrote:
> The test "(table[which].blit_features & GetBlitFeatures()) ==
> table[which].blit_features)" is correct, and the previous
> "(table[which].cpu_mmx == SDL_HasMMX())" was actually broken.
I think there is potentially a slightly different cause of the above problem.
During the introduction of the Altivec code, the blit_table struct field
'alpha' got changed from a straightforward enum to a bitmask, which makes
perfect sense by itself. However, now the table driven blitter selection code
in SDL_CalculateBlitN() can choose the wrong blitters when searching for a
NO_ALPHA blitter because of the following code:
int a_need = 0;
...
(a_need & table[which].alpha) == a_need &&
When searching through the normal_blit_2[] table, a SET_ALPHA blitter (like
Blit_RGB565_ARGB8888) can now be selected instead of a NO_ALPHA one, causing
alpha channel bits to appear in a non-alpha destination surface. I suppose this
could theoretically be an indirect cause of the segfault mentioned above.
I *think* this can be fixed by changing to
int a_need = NO_ALPHA;
author | Sam Lantinga <slouken@libsdl.org> |
---|---|
date | Wed, 15 Mar 2006 15:47:49 +0000 |
parents | 355632dca928 |
children |
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<HTML ><HEAD ><TITLE >SDL_JoyButtonEvent</TITLE ><META NAME="GENERATOR" CONTENT="Modular DocBook HTML Stylesheet Version 1.76b+ "><LINK REL="HOME" TITLE="SDL Library Documentation" HREF="index.html"><LINK REL="UP" TITLE="SDL Event Structures." HREF="eventstructures.html"><LINK REL="PREVIOUS" TITLE="SDL_JoyAxisEvent" HREF="sdljoyaxisevent.html"><LINK REL="NEXT" TITLE="SDL_JoyHatEvent" HREF="sdljoyhatevent.html"></HEAD ><BODY CLASS="REFENTRY" BGCOLOR="#FFF8DC" TEXT="#000000" LINK="#0000ee" VLINK="#551a8b" ALINK="#ff0000" ><DIV CLASS="NAVHEADER" ><TABLE SUMMARY="Header navigation table" WIDTH="100%" BORDER="0" CELLPADDING="0" CELLSPACING="0" ><TR ><TH COLSPAN="3" ALIGN="center" >SDL Library Documentation</TH ></TR ><TR ><TD WIDTH="10%" ALIGN="left" VALIGN="bottom" ><A HREF="sdljoyaxisevent.html" ACCESSKEY="P" >Prev</A ></TD ><TD WIDTH="80%" ALIGN="center" VALIGN="bottom" ></TD ><TD WIDTH="10%" ALIGN="right" VALIGN="bottom" ><A HREF="sdljoyhatevent.html" ACCESSKEY="N" >Next</A ></TD ></TR ></TABLE ><HR ALIGN="LEFT" WIDTH="100%"></DIV ><H1 ><A NAME="SDLJOYBUTTONEVENT" ></A >SDL_JoyButtonEvent</H1 ><DIV CLASS="REFNAMEDIV" ><A NAME="AEN4258" ></A ><H2 >Name</H2 >SDL_JoyButtonEvent -- Joystick button event structure</DIV ><DIV CLASS="REFSECT1" ><A NAME="AEN4261" ></A ><H2 >Structure Definition</H2 ><PRE CLASS="PROGRAMLISTING" >typedef struct{ Uint8 type; Uint8 which; Uint8 button; Uint8 state; } SDL_JoyButtonEvent;</PRE ></DIV ><DIV CLASS="REFSECT1" ><A NAME="AEN4264" ></A ><H2 >Structure Data</H2 ><DIV CLASS="INFORMALTABLE" ><A NAME="AEN4266" ></A ><P ></P ><TABLE BORDER="0" CLASS="CALSTABLE" ><TBODY ><TR ><TD ALIGN="LEFT" VALIGN="TOP" ><TT CLASS="STRUCTFIELD" ><I >type</I ></TT ></TD ><TD ALIGN="LEFT" VALIGN="TOP" ><TT CLASS="LITERAL" >SDL_JOYBUTTONDOWN</TT > or <TT CLASS="LITERAL" >SDL_JOYBUTTONUP</TT ></TD ></TR ><TR ><TD ALIGN="LEFT" VALIGN="TOP" ><TT CLASS="STRUCTFIELD" ><I >which</I ></TT ></TD ><TD ALIGN="LEFT" VALIGN="TOP" >Joystick device index</TD ></TR ><TR ><TD ALIGN="LEFT" VALIGN="TOP" ><TT CLASS="STRUCTFIELD" ><I >button</I ></TT ></TD ><TD ALIGN="LEFT" VALIGN="TOP" >Joystick button index</TD ></TR ><TR ><TD ALIGN="LEFT" VALIGN="TOP" ><TT CLASS="STRUCTFIELD" ><I >state</I ></TT ></TD ><TD ALIGN="LEFT" VALIGN="TOP" ><TT CLASS="LITERAL" >SDL_PRESSED</TT > or <TT CLASS="LITERAL" >SDL_RELEASED</TT ></TD ></TR ></TBODY ></TABLE ><P ></P ></DIV ></DIV ><DIV CLASS="REFSECT1" ><A NAME="AEN4289" ></A ><H2 >Description</H2 ><P ><SPAN CLASS="STRUCTNAME" >SDL_JoyButtonEvent</SPAN > is a member of the <A HREF="sdlevent.html" ><SPAN CLASS="STRUCTNAME" >SDL_Event</SPAN ></A > union and is used when an event of type <TT CLASS="LITERAL" >SDL_JOYBUTTONDOWN</TT > or <TT CLASS="LITERAL" >SDL_JOYBUTTONUP</TT > is reported.</P ><P >A <TT CLASS="LITERAL" >SDL_JOYBUTTONDOWN</TT > or <TT CLASS="LITERAL" >SDL_JOYBUTTONUP</TT > event occurs when ever a user presses or releases a button on a joystick. The field <TT CLASS="STRUCTFIELD" ><I >which</I ></TT > is the index of the joystick that reported the event and <TT CLASS="STRUCTFIELD" ><I >button</I ></TT > is the index of the button (for a more detailed explaination see the <A HREF="joystick.html" >Joystick section</A >). <TT CLASS="STRUCTFIELD" ><I >state</I ></TT > is the current state or the button which is either <TT CLASS="LITERAL" >SDL_PRESSED</TT > or <TT CLASS="LITERAL" >SDL_RELEASED</TT >.</P ></DIV ><DIV CLASS="REFSECT1" ><A NAME="AEN4306" ></A ><H2 >See Also</H2 ><P ><A HREF="sdlevent.html" ><SPAN CLASS="STRUCTNAME" >SDL_Event</SPAN ></A >, <A HREF="joystick.html" >Joystick Functions</A >, <A HREF="sdljoystickeventstate.html" ><TT CLASS="FUNCTION" >SDL_JoystickEventState</TT ></A >, <A HREF="sdljoystickgetbutton.html" ><TT CLASS="FUNCTION" >SDL_JoystickGetButton</TT ></A ></P ></DIV ><DIV CLASS="NAVFOOTER" ><HR ALIGN="LEFT" WIDTH="100%"><TABLE SUMMARY="Footer navigation table" WIDTH="100%" BORDER="0" CELLPADDING="0" CELLSPACING="0" ><TR ><TD WIDTH="33%" ALIGN="left" VALIGN="top" ><A HREF="sdljoyaxisevent.html" ACCESSKEY="P" >Prev</A ></TD ><TD WIDTH="34%" ALIGN="center" VALIGN="top" ><A HREF="index.html" ACCESSKEY="H" >Home</A ></TD ><TD WIDTH="33%" ALIGN="right" VALIGN="top" ><A HREF="sdljoyhatevent.html" ACCESSKEY="N" >Next</A ></TD ></TR ><TR ><TD WIDTH="33%" ALIGN="left" VALIGN="top" >SDL_JoyAxisEvent</TD ><TD WIDTH="34%" ALIGN="center" VALIGN="top" ><A HREF="eventstructures.html" ACCESSKEY="U" >Up</A ></TD ><TD WIDTH="33%" ALIGN="right" VALIGN="top" >SDL_JoyHatEvent</TD ></TR ></TABLE ></DIV ></BODY ></HTML >